KSEEB Class 10 SSLC Biology Chapter 5 Our Environment

The physical and biological world where we live is called our environment. The environment includes our physical surroundings like air (or atmosphere), water bodies, soil (land) and all the organisms such as plants, animals, human beings and micro-organisms like bacteria and fungi (called decomposers).

All these constituents of the environment are dependent on one another. So, all the constituents of environment interact with one another and maintain a balance in the environment in a natural way.

Human beings are the only organisms who change the natural environment to fulfil their needs of food, clothing, housing, transport and industry, etc. In fact, the uncontrolled activities of human beings are damaging the balanced and healthy environment more and more.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Biodegradable And Non-Biodegradable Wastes

All the waste materials produced by the various activities of man and animals are poisonous to some extent and can be divided into two main groups :

1. Biodegradable wastes, and
2. Non-biodegradable wastes.

Those waste materials which can be broken down to non-poisonous substances in nature in due course of time by the action of micro-organisms like certain bacteria, are called biodegradable wastes.

• A biodegradable waste decays (decomposes) naturally and becomes harmless after some time. Cattle dung and compost are common examples of biodegradable wastes. [Compost is the manure made from decayed vegetable-stuff (plants)].
• Other examples of biodegradable materials are: Animal bones ; Leather ; Tea- leaves ; Wool ; Paper ; Wheat ; Wood ; Hay ; Cotton ; Jute ; Grass ; Fruit and Vegetable peels ; Leaves, Flowers, and Cake, etc. Biodegradable wastes usually do not pollute the environment.
• Biodegradable wastes pollute the environment only when their amount is large which cannot be degraded (or decomposed) into harmless substances in nature at the right time.
• The waste materials which cannot be broken down into non-poisonous or harmless substances in nature are called non-biodegradable wastes.
• The examples of non-biodegradable wastes are: D.D.T. (Dichloro Diphenyl Trichloroethane); Plastics; Polythene bags; Ball-point pen refill; Synthetic fibres; Glass objects; Metal articles like Aluminium cans; Iron nails; Silver foil and Radioactive wastes.
• All these non-biodegradable wastes cannot be made less toxic (less poisonous) easily and hence they are major pollutants of the environment.
• The non-biodegradable wastes cannot be decomposed by micro-organisms like bacteria. D.D.T. is a non-biodegradable waste so it can be passed along the food chain from crops to man or other animals and birds and harm them.
• For this reason, D.D.T. has been banned from use in most countries. Non-biodegradable wastes are the major pollutants of the environment. For example, the discarded plastic articles, glass articles and metal objects are the non-biodegradable waste materials which cause a lot of pollution in our surroundings.
• We will now describe a simple experiment to find out whether a given material is biodegradable or non-biodegradable. We take a piece of paper, a piece of an old cotton cloth and a plastic bag (polythene bag).

• Dig the ground to about 15 centimetres depth and place the pieces of paper, cotton cloth and plastic bag in the dug up ground separately. We cover them with soil.
• Leave these buried materials in the ground for about a month. After a month, we dig up the buried materials and observe them. We will find that the piece of paper and the piece of cotton cloth have been partially eaten up (or decomposed) but the plastic bag has remained unaffected, it has not been eaten up (or decomposed).
• This means that paper and cotton cloth have been decomposed by the micro-organisms present in the soil. So, paper and cotton cloth are biodegradable.
• On the other hand, the plastic bag has not been decomposed by the micro-organisms present in the soil, therefore, plastic is non-biodegradable. So, the decomposer organisms are not able to decompose plastic into simpler harmless substances.
• We will now explain why some materials are biodegradable whereas others are non-biodegradable. The micro-organisms like bacteria and other decomposer organisms (called saprophytes) present in our environment are ‘specific’ in their action.
• They break down the natural materials or products made from natural materials (say, paper) but do not break down man-made materials such as plastics. So, it is due to the property of decomposer organisms of being specific in their action that some waste materials are biodegradable whereas others are non-biodegradable.
• We should use the shopping bags (or carry bags) made of paper, cotton cloth or jute because these are biodegradable materials.
• On the other hand, plastic bags (or polythene bags) should be avoided because plastic is a non-biodegradable material.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Ecosystem

• The various communities of living organisms (plants and animals) interact among themselves as well as with their physical environment like soil, air and water. The living organisms interact with one another through their food chains in which one organism consumes another organism.
• The living organisms like plants interact with soil to get essential nutrients like nitrogen, phosphorus, etc.; with air to get carbon dioxide and also with water bodies, for carrying out the process of photosynthesis.

• Thus, the various communities of living organisms (called biotic communities) like plants and animals alongwith soil, air and water of that region form a self-sustaining or functional unit of the living world. This ‘functional unit’ or ‘system’ made up of living and non-living components which is capable of independent existence is called an ecosystem.
• The ecosystem includes all the communities of an area (all the plants and animals of an area) functioning with their non-living environment like soil, air and water. We can now define an ecosystem as follows.
• An ecosystem is a self-contained unit of living things (plants, animals and decomposers), and their non-living environment (soil, air and water). An ecosystem needs only the input of sunlight energy for its functioning. The examples of ecosystems are : a grassland (meadow); a forest; a desert; a mountain; a pond; a lake; a river; and sea.
• When we say that a pond or lake is an ecosystem, then the word pond also includes all the aquatic life (plants and animals) which occurs in this pond water. This is because the living organisms are found everywhere. Similarly, when we say that a forest is an ecosystem then it means the physical environment of the forest like soil, air and water alongwith all the plants and animals which occur in the forest.
• The desert, grassland, forest, cropfield and mountains represent terrestrial ecosystems (land- based ecosystems) whereas ponds, lakes, river, sea and aquarium represent aquatic ecosystems (water- based ecosystems).
• Most of the ecosystems in the world are natural ecosystems but some of them are also man-made ecosystems or artificial ecosystems. The examples of artificial ecosystems are crop-fields (agricultural lands); gardens; parks and aquarium

Components of an Ecosystem

All the ecosystems are made up of two main components: Abiotic components, and Biotic components. Abiotic components mean non-living components and biotic components mean living components. Thus, we can now say that an ecosystem consists of non-living environment and the living biological community.

Abiotic Components of an Ecosystem.

• The abiotic components of an ecosystem (or the non-living components of an ecosystem) include the physical environment like soil, water and air alongwith the inorganic substances like carbon dioxide, nitrogen, oxygen, water, phosphorus, sulphur, sodium, potassium, calcium and other elements present in them. The physical factors or climatic factors like light, temperature, pressure and humidity are also considered abiotic components of the ecosystem.

Biotic Components of an Ecosystem.

• The biotic component of an ecosystem (or the living component of an ecosystem) is a community of organisms (like plants and animals), which is made up of many different inter-dependent populations. The biotic community (or living community) of an ecosystem includes three types of organisms :
• Producer organisms (or Autotrophs) which synthesize their own food. All the green plants are producers.
• Consumer organisms (or Heterotrophs) which are dependent on others for food. All the animals are consumers.
• Decomposer organisms (or Saprotrophs) which consume the dead remains of other organisms. Certain bacteria and fungi are decomposers.

The Functioning of an Ecosystem

• We will now describe how an ecosystem functions as a self-sufficient or independent unit in nature.
• We have just discussed that an ecosystem has non-living components like soil, water and air which contain inorganic nutrient elements, and the living components called producers, consumers and decomposer organisms. All these components make the ecosystem function as follows: From the nutrient pool of the earth (soil, water and air), carbon dioxide and water are absorbed by the producer organisms (green plants).
• With the help of sunlight energy, the producer organisms convert these inorganic substances into organic compounds like carbohydrates which act as a food. Thus, producers trap the solar energy and then provide the basic food or energy for all other life forms in the ecosystem. The consumers (animals) derive their energy needs, directly or indirectly, from producers (plants).
• When the producers (plants) and consumers (animals) die, then the decomposer organisms act on their dead bodies to return the various elements back to the nutrient pool (soil, water and air). Thus, an ecosystem involves input of energy and matter which are exchanged between living and non-living components in a cyclic process.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Producers, Consumers and Decomposers

According to the manner in which they obtain their food from the environment, all the organisms can be divided into three groups : producers, consumers and decomposers.

Producers

• Those organisms which produce food are called producers. Producers are the organisms which can prepare their own food from simple inorganic substances like carbon dioxide and water by using sunlight energy in the presence of chlorophyll.

• The examples of producers are green plants and certain blue-green algae. The green plants synthesize their food during photosynthesis by taking raw materials from the earth and energy from the sun The green plants produce carbohydrates by photosynthesis and also synthesize proteins and fats.
• Thus, the green plants are called producers in the living world. Producers are the autotrophic organisms (self- feeder organisms) in the ecosystem upon which other organisms depend for food. Thus, producers (like green plants) are autotrophs.

Consumers

• Those organisms which consume food (eat food) prepared by producers are called consumers. The consumers depend on producers for food, directly or indirectly. The consumers get their food by eating other organisms or their products. In most simple words, consumers are the organisms that eat other organisms.
• All the animals are consumers. Even the microscopic animal life of the water called protozoa are consumer organisms. The examples of common consumer organisms are man, goat, deer, fish, lion, cow and buffalo, etc. The cow and buffalo eat green grass and other green fodder because green grass and other green plants are producers of food.

• The bio-mass of grass and plants supplies food and energy to these animals like cow and buffalo. It should be noted that the consumer organisms like animals cannot prepare food from simple inorganic substances through photosynthesis. The consumers need ready-made food for their survival which they get from producers (green plants), either directly or indirectly.
• If an animal eats grass or other green plants or their products itself we say that it gets the food from producers directly. For example, a goat gets the food from producers directly when it eats grass. On the other hand, if an animal eats the meat of another animal (which eats grass), then we say that it gets the food from producer indirectly.
• For example, a lion gets food by eating goat which in turn eats grass. So, in this case the lion gets its food indirectly from producer grass (through the goat). Consumer organisms are also called heterotrophs.Consumers can be further divided into three groups : herbivores, carnivores and omnivores.

Herbivores

Some animals eat only plants (or their products). Those animals which eat only plants are called herbivores. The herbivores may eat grasses, leaves, grains, fruits or the bark of trees. Some of the examples of herbivores are : Cow, Buffalo, Goat, Sheep, Horse, Deer, Camel, Ass, Ox, Elephant, Monkey, Squirrel, Rabbit and Hippopotamus. Cow is called a herbivore because it eats only plants (or plant products) as food. Herbivores are also known as herbivorous animals. The animals which get their food by eating the producers (plants) directly are called primary consumers. Since herbivores obtain their food directly from plants (or producers), therefore, herbivores (like cattle, deer, goat, etc.) are primary consumers.

Carnivores

• Some animals eat only other animals. They do not eat plant food at all. Those animals which eat only other animals as food are called carnivores. The carnivores eat the meat (or flesh) of other animals. So, we can also say that those animals which eat only the meat (or flesh) of other animals are called carnivores.

• Some of the examples of the carnivores are : Lion, Tiger, Frog, Vulture, Kingfisher, Lizard, Wolf, Snake and Hawk. Lion is called a carnivore because it eats only the meat (or flesh) of other animals like deer, rabbit and goat, etc. Carnivores are also known as carnivorous animals. The carnivores are usually of two types : small carnivores and large carnivores.
• The small carnivores which feed on herbivores (primary consumers) are called secondary consumers. For example, a frog, lizard, bird and fox, etc., are secondary consumers. The large carnivores (or top carnivores) which feed upon the small carnivores (secondary consumers) are called tertiary consumers.
• For example, lion, tiger and birds of prey (such as hawk) are some of the tertiary consumers. Please note that humans (man) can be primary, secondary or tertiary consumers depending on the food which they eat.

Omnivores

• Some animals eat both, plants as well as other animals. Those animals which eat both, plants and animals, are called omnivores. In other words, the omnivores eat plant food as well as the meat (or flesh) of other animals.
• Some of the examples of omnivores are : Man (human beings), Dog, Crow, Sparrow, Bear, Mynah and Ant. Man is called an omnivore because he eats both, plant food (such as grains, pulses, fruits and vegetables) as well as meat of animals (such as goat, chicken and fish).
• Omnivores are also called omnivorous animals.We will now describe another type of producers and consumers which are extremely small. These are called planktons. Planktons are very minute or microscopic organisms freely floating on the surface of water in a pond, lake, river or ocean. Planktons are of two types : Phytoplanktons and Zooplanktons.

• The microscopic aquatic plants freely floating on the surface of water are called phytoplanktons. The free-floating algae is an example of phytoplankton. Phytoplanktons are capable of producing food by the process of photosynthesis. The microscopic aquatic animals freely floating on water are called zooplanktons.
• The freely-floating protozoa are an example of zooplankton. A very, very small fish is also a zooplankton. Planktons float near the surface of water and provide food for many fish and other aquatic animals.

Decomposers

• The non-green micro-organisms like some bacteria and fungi, which are incapable of producing their food, live on the dead and decaying (rotting) plants and animal bodies and are consumers of a special type called decomposers.
• We can now say that: The micro-organisms which break down the complex organic compounds present in dead organisms like dead plants and animals and their products like faeces, urine, etc., into simpler substances are called decomposers.

• The examples of decomposers are certain bacteria and fungi. The bacteria which act as decomposers are called putrefying bacteria. The bacteria and fungi act as decomposers by the secretions of their body surfaces which decompose the organic matter present in dead plants and animals into simpler substances and liberate ammonia, carbon dioxide, etc.
• They absorb some of these simpler substances for their own maintenance and release the remaining into the soil, water and air to be used by the producers again In this way, decomposers help in the recycling of materials in ecosystem. The decomposers are also known as micro-consumers or saprotrophs.

Importance of Decomposers

• The decomposers help in decomposing the dead bodiesof plants and animals, and hence act as cleansing agents of environment. The decomposers also help in putting back the various elements of which the dead plants and animals are made, back into the soil, air and water for re-use by the producers like crop-plants.
• This maintains the fertility of soil and the soil would continue to support crops again and again. For example, the decomposers like putrefying bacteria and fungi decompose the dead plants and animal bodies into ammonia (and other simpler substances). This ammonia is converted into nitrates by the nitrifying bacteria present in soil.
• These nitrates act as fertilizer in the soil and are again absorbed by the plants for their growth. Thus, it is only due to the presence of decomposers that the various nutrient elements which were initially taken by plants from the soil, air and water are returned to the soil, air and water, after the death of plants and animals.

• If, however, there were no decomposers, then the dead bodies of plants and animals would keep lying as such and the elements of which plant and animal bodies are made, would never be returned to their original pools like soil, air and water. In that case, the cyclic process of life and death would be disrupted.
• This is because in the absence of decomposers the soil, air and water would not be replenished by elements from the bodies of dead organisms. All the nutrients present in soil, air and water would soon be exhausted and evolution of life would come to an end.
• Thus, the decomposer organisms help in recycling the materials in the ecosystem so that the process of life may go on and on like an unending chain.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment  Food Chains

• Anything which we eat to live is called food. Food contains energy. The food (or energy) can be transferred from one organism to the other through food chains. The starting point of a food chain is a category of organisms called producers.
• Producers are, in fact, plants. So, we can say that all the food chains begin with a green plant (or grass) which is the original source of all food. Let us take an example to understand the meaning of food chain.

• Suppose there is a field having a lot of green plants (or producers of food). Now, plants can be eaten up by a rat. The rat, in turn, can be eaten up by a cat. And finally, the cat can be eaten up by a dog. So, we find that there is a sequence (or order) in which one organism eats up the other organism (or consumes the other organism) to fill its belly.
• The sequence of living organisms in a community in which one organism consumes another organism to transfer food energy, is called a food chain. In simple words, a list of organisms (living beings) showing “who eats whom” is called a food chain.
• Let us make this point more forest, there is a lot of grass (which are green plants). This grass is eaten up by animals like deer. And this deer is then consumed (eaten up) by a lion. This simple food chain operating in a grassland or forest can be represented as :
• Grass ——————- Deer————————  Lion
• (Producer) ———–(Herbivore) —————–(Carnivore)
• This food chain tells us that grass is the starting point of this food chain. The grass is eaten up by deer and the deer is then eaten up by a lion. In this food chain, grass is the producer organism which uses sunlight energy to prepare food like carbohydrates by the process of photosynthesis.
• This grass is then consumed by a herbivore called deer. And the deer is consumed by a carnivore called lion. The above food chain can be represented more clearly .
•  A food chain represents a single directional (or unidirectional) transfer of energy. For example, theabove food chain tells us that the transfer of energy takes place from grass to deer and then to lion. It cannot take place in the reverse direction from lion to deer to grass. The study of food chains in an area or habitat helps us in knowing various interactions among the different organisms and also their interdependence.

More Examples of Food Chains

• In the food chain that we have discussed above, there are three organisms involved in it : grass, deer and lion, so it is said to be a food chain having three steps or three links.
• The same grassland has many other food chains operating in it which can have different number of steps. Let us take the example of a grassland food chain having four steps or four links.
• In a grassland ecosystem, grass is eaten by insects; the insects are eaten by frog; and the frog is then eaten by birds. This is a grassland food chain involving four organisms (or four steps) which can be represented as follows :

• Please note that in this food chain grass is the producer. The insect (herbivore) is the primary consumer, the frog (small carnivore) is the secondary consumer whereas the bird (top carnivore or large carnivore) is the tertiary consumer.
• Another four-step food chain operating in a grassland is :
• Plants —————-Worms—–———– Birds —————Cat (Producer)——– (Herbivore)———– (Carnivore)——–(Top carnivore)
• We will now discuss the food chain operating in an aquatic ecosystem (water ecosystem) like a pond, lake, or sea (ocean). In a pond, lake or sea ecosystem, the algae are eaten up by protozoa; the protozoa are eaten up by small fish; and the small fish is eaten up by big fish. This aquatic food chain can be represented as :
• Algae —————-Protozoa ———-Small Fish ———– Big Fish (Phytoplankton)
• Please note that in a pond, lake or ocean ecosystem, the producer is a minute organism called algae and protozoa is the minute herbivore.

• Each organism (or living being) occupies a specific position in the food chain. For example, grass, deer and lion occupy specific positions in the food chain :
• Grass —————————-Deer ——–————————Lion
• Another point to be noted is that one organism (or same organism) can occur in more than one food chains. For example, in the forest food chains, a deer may be consumed by a lion as well as by a jackal :
• Grass————————– Dee——————————- Jackal
• So, the same organism, deer, occurs in the food chains of lion as well as that of jackal. The organisms representing producers and consumers in a food chain give a definite structure to an ecosystem.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment  Food Web

• A large number of food chains exist in a community of living organisms in an ecosystem such as a grassland, a forest, a pond or a crop-field. Many of these food chains are inter-connected by species (organisms) which occur in more than one food chain.
• The inter-connected food chains operating in an ecosystem which establish a network of relationships between various species, is called a food web. In simple words, the network of a large number of food chains existing in an ecosystem is called a food web.
• The food web has many intercrosses and linkages among the various species (producers and consumers) present in it. This means that the various food chains in an ecosystem do not operate in isolation (or alone). They operate in the form of a net-work of food chains called food web. A food web.
• This is a food web. A food web consists of many inter-connected food chains. In this food web, we can see a network of numerous pathways along which the food (or energy) flows within grassland community.
• This food web starts from the plants which is a producer and ends in top carnivore hawk (baaz). There are as many as six food chains operating in the food web shown above which have been marked 1, 2, 3, 4, 5 and 6.

1. In the 1st food chain, plants are eaten by rabbit and then rabbit is eaten by hawk :     Plants ——- Rabbit ——– Hawk
2. In the 2nd food chain, plants are eaten by mice (or rats) and the mice are eaten by hawks :        Plants ——– Mice ——– Hawk

3. In the 3rd food chain, plants are eaten by mice; mice are eaten by snakes and then snakes are consumed by hawks :                          Plants  ——– Mice——–Snake ——– Hawk

4. In the 4th food chain, plants are eaten by seed-eating birds and the seed-eating birds are consumed by hawks :                                    Plants ——– Seed-eating Bird ———– Hawk

5. In the 5th food chain, plants are eaten up by grasshopper and the grasshopper is consumed by hawks: Plants  Grasshopper  Hawk

6. In the 6th food chain, plants are eaten by grasshopper, grasshopper is eaten by frog, frog is eaten by snake and then snake is consumed by hawk : Plants——-Grasshopper ——–Frog——- Snake  —–Hawk

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Trophic Levels

• A food chain represents the flow of food (or energy) in a given set of organisms or living beings. The various steps in a food chain at which the transfer of food (or energy) takes place are called trophic levels. In fact, in a food chain, each step representing an organism forms a trophic level. In most simple terms, ‘trophic level’ means ‘feeding level’ of the organism.

1. The plants are producers (or autotrophs) and constitute the first trophic level. They fix up the sun’s energy and make it available for consumers (or heterotrophs).
2. Herbivores (which feed upon plants) constitute the second trophic level.
3. Carnivores (that feed upon herbivores) constitute the third trophic level.
4. Large carnivores or Top carnivores (which feed upon small carnivores), constitute the fourth trophic level.

The various trophic levels in a food chain can be represented diagrammatically.

• Top carnivores (Fourth trophic level)Carnivores (Third trophic level) Herbivores(Second trophic level) Producers (First trophic level) Tertiary consumers Secondary consumers Primary consumers Producers.
•  Herbivores are called primary consumers, small carnivores are called secondary consumers whereas top carnivores or large carnivores are called tertiary consumers. So, we can draw another diagram to represent various trophic levels by using the terms producers, primary consumers, secondary consumers and tertiary consumers.
• Please note that both, secondary consumers and tertiary consumers are carnivores, the only difference being that secondary consumers are small carnivores (though we usually do not write the word small), whereas tertiary consumers are large carnivores which are usually called top carnivores is tapering upwards because as we go up towards higher trophic levels, the number of organisms in them decreases gradually.
• The simplest food chain that we have already studied is :
• 
• Now, this food chain involves three trophic levels. Grass (being producer) represents the 1st trophiclevel. Deer (being herbivore) represents the 2nd trophic level, and lion (being carnivore) represents the third trophic level.
• We have also studied another food chain operating in the grassland, which is :
•  In this food chain, grass represents the 1st trophic level; insects represent the 2nd trophic level; frog represents the 3rd trophic level, whereas birds represent 4th trophic level. This is shown more clearly.

• We will now consider some of the food chains involving man(human beings). Now, when man eats plants (or plant products), then the food chain involves only producer and consumer
• 
• This food chain has only two trophic levels. Plants being the first trophic level and the man representing second trophic level. But in the case of man who also eats meat (of animals like goat), the food chain involves producer and two consumers, the primary consumer and the secondary consumer :
• 
• This food chain involving man has three trophic levels. Plants represent 1st trophic level, goat represents 2nd trophic level whereas man represents the 3rd trophic level.
• The trophic levels in a food chain can also be represented by pyramid of numbers. Thus, if we count the number of species (or organisms) living at each trophic level in a food chain, then we can represent the food chain by a pyramid of numbers. A pyramid of numbers showing the various trophic levels in the grassland food chain :
• Plants –Mice –Snakes–Hawks The base of this pyramid is formed by producers (plants) and the top of this pyramid is formed by the highest order consumers (or top carnivores).
• 
• Please note that the same ecosystem may besupporting many different pyramids of organisms, each starting with plants at the base but ending in a different organism at the top. Another point to be noted is that there is a greater number of organisms at the lower trophic levels of an ecosystem (the greatest number being at the producer level). As we go to higher and higher trophic levels, the number of organisms in each trophic level goes on decreasing.

Effect of Man’s Activities on the Ecosystem

• Man or for that matter, any other living organism must interact properly with the rest of the ecosystem because he is an integral part of that ecosystem. Some of the man’s activities like hunting of various animals disrupt the food chains in which these animals normally take part.
• This disruption of one food chain affects the numerous other food chains operating in the food web. The shortening of food chains due to man’s activities like hunting leads to an imbalance in the functioning of an ecosystem and ultimately in the functioning of the whole biosphere. The effect of man’s activities on the functioning of an ecosystem will become clear from the following examples.
• The formation of Sahara Desert is an example of the ill effect of man’s activities on the delicately balanced ecosystem.
• When the Romans started capturing lions, the population of lions in the forest was reduced to a large extent Lion is a predator which kills the herbivorous animals like deer, sheep, goat, buffalo, etc. Now, since the population of predator lion decreased, there was no one to kill the herbivorous animals. Due to this the population of herbivorous animals increased rapidly.
• The large population of these herbivorous animals ate up all the vegetation (plant materials) in that region, turning the lush-green forests into vast desert called Sahara Desert. Our own Rajasthan Desert was formed as a result of overgrazing of vegetation by progressively increasing tribes of herbivorous animals which occurred due to the reduction in the predator population of lions because of excessive hunting and capturing.
• Let us take the example of Grass —Deer —-Lion food chain to study the effect of man’s activities on the ecosystem. A natural ecosystem is a delicately balanced system. If the man does not disturb this ecosystem, then the organisms like grass, deer and lion in a forest keep a natural balance which benefits them all and gives us a healthy environment. We will now discuss the effect of removing all the three organisms from this food chain, one at a time.

If All the Lions are Removed

• If all the lions in a forest are removed by killing or capturing, then there will be no predator control over the population of deer. Due to this the population of deer will increase greatly. Deer eat grass. So, an increase in deer population will lead to excessive grazing of grass. The density of producers like grass will be very much reduced. Overgrazing may even eliminate the grass and other green plants completely and turn the lush-green forest into a desert area having no vegetation at all.

If All the Deer are Removed

• Deer is a food (or prey) for lion. Now, if somehow, all the deer population from a forest is removed, then there will not be sufficient food for the lions. Some of the lions will die because of starvation and hence the population of lions will decrease.
• The decrease in population of lions will disturb other food chains in which lions operate. The hungry lions of the forest can come out of the forest in search of food and may even kill domestic animals or human beings for obtaining food.
• If the lion and deer are operating in other food chains of the food web, the removal of deer population and the subsequent reduction in lion population will disturb the balance of ecosystem.

If All the Producers are Removed

• If all the producers like grass and other plants are removed, then no deer or lion (or any other organism) will be able to exist. This is because the food and energy necessary for sustaining life is derived from the producer organisms like grass, plants and their products.
• From the above examples we conclude that if we kill all the organisms in one trophic level, it will cause too much damage to the environment. So, we cannot remove all the organisms of a trophic level without causing any damage to the ecosystem.
• The impact of removing all the organisms of a trophic level will be different for different trophic levels (as explained in the above given examples). We will now answer some questions based on trophic levels.

Sample Problem 1. Which of the following belong to the same trophic level ?

Grass; Hawk; Rabbit; Frog; Deer

Solution. Here, grass is a producer, hawk is a top carnivore, rabbit is a herbivore, frog is a carnivore and deer is a herbivore. Since rabbit and deer are both herbivores, so they belong to the same trophic level (2nd trophic level).

Sample Problem 2. Which of the following belong to the same trophic level ?

Frog; Grasshopper; Grass; Snake; Algae

Solution. Here, frog is a carnivore, grasshopper is a herbivore, grass is a producer, snake is a top carnivore, and algae is producer. Since grass and algae are both producers, so they belong to the same trophic level (1st trophic level)

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment The Sun Provides Energy For Maintaining All Life On Earth

All the organisms (plants and animals) depend on the sun for their constant need of energy, and upon earth for the materials which enter into their body. We will now describe how energy received from the sun flows in the various trophic levels of an ecosystem in the form of chemical energy of food.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Transfer Of Energy In Food Chains

• The food chain in a community actually represents a stepwise transfer of food and the energy contained in food. The food and energy enter the living components of the ecosystem through the process of photosynthesis.
• This is because photosynthesis is a process which combines the substances like carbon dioxide, water and sunlight energy to form food like carbohydrates and converts light energy of the sun into chemical energy of carbohydrates.
• This food and energy is then transferred from the producer organisms to herbivores and from herbivores to carnivores, through the food chain. Let us discuss this flow of energy in detail.

First Step

• The green plants (or producers) have a mechanism for trapping solar energy (sun’s energy) with the help of their green pigment called chlorophyll. The green plants after trapping the solar energy, convert it into chemical energy which is stored as carbohydrates in the plants.
• Thus, the initialpoint where energy from the environment enters into the living components of ecosystem (like plants and animals) is theprocess of preparation of food by green plants through photosynthesis. On an average, about 1% of the sun’s energy falling on the leaves is used by the plants in the process of photosynthesis and stored as chemical energy of food.

• The plants utilisethe energy stored in them for their metabolicactivities like respiration and growth (tissue building). Some of the energy is, however, not utilized and it is released as unusable heat into the community environment.

Second Step

• The plants (or producers) are eaten up by herbivores. The chemical energy stored in plant food is transferred with food to herbivores. The herbivores utilize this energy for their various metabolic activities like respiration and also for their growth. Some of the energy, however, remains unutilized which is released by the herbivores as heat energy to the environment.

Third Step

• The herbivores are eaten up or consumed by carnivores. The chemical energy stored in the flesh of herbivores is transferred with food (or flesh) to the carnivores. The carnivores utilize this energy for their various metabolic activities like respiration and also for their growth. Some of the energy, however, remains unutilized by the carnivores and it is released as heat energy into the environment.
• This process of the transfer of energy is repeated with large carnivores or top carnivores (who eat small carnivores), and so on. It should be noted that some of the energy from producers and consumers (like plants, herbivores and carnivores) is also utilized for the life processes of micro-organisms called decomposers. The decomposers, in turn, release the unutilized energy as heat into the environment.

1. It is obvious from the above discussion that the energy which remains unutilized by producers, consumers (herbivores and carnivores) and decomposers is lost into the environment as heat. It is called community heat. We should remember the following points about the transfer of energy in the ecosystem :
2. Energy is not created in the ecosystem. Energy is only converted from one form to another. For example, light energy coming from the sun is converted into chemical energy of food like carbohydrates by the process of photosynthesis. Thus, photosynthesis converts light energy into chemical energy.
3. There is a continuous transfer of energy from one trophic level of organisms to the next trophic level in a food chain. For example, producers like plants transfer energy to the herbivorous animals like deer, and the herbivorous animals like deer transfer energy to carnivorous animals like lion, so that there is a continuous transfer of energy in the food chain : Plants o Deer o Lion. This transfer of energy takes place in the form of chemical energy of food.
4. At each trophic level of organisms, some of the energy is utilized by the organisms for their metabolic
5. A part of the energy at each trophic level (like producers, herbivores and carnivores) is utilized for the functioning of decomposers.
6. There is a loss of energy at each energy transfer in various trophic levels of organisms which goes into the environment and remains unutilized. In other words, we can say that the amount of energy available at each successive trophic level is less than the energy available at the producer level. Thus, when we move from the first trophic level of producers (plants) to second trophic level of herbivores and thirdtrophic level of carnivores, the amount of energy available gradually decreases. This is because at each trophic level, energy is lost as heat energy which goes into the environment.

Flow of Materials in Ecosystem is Cyclic but Flow of Energy is Unidirectional

• The materials like water, carbon (as carbon dioxide) and nitrogen (as minerals) are taken up by the plants from soil, air and water bodies, etc., and made into food. This food is then passed on to the animals like herbivores and carnivores in a food chain.
• After the death and decay of plants and animals, the materials like water, carbon and nitrogen present in their bodies are returned to soil, air and water, from where they were taken originally. These materials can then be reused for the growth of new plants. In this way, the same materials are used again and again, the materials are not lost from the environment. of materials like water, carbon and nitrogen, etc., in the ecosystem is said to be cyclic. This is not so in the
  case of energy.
  
• The flow of energy in the ecosystem is unidirectional (or one-directional). The energy enters the plants (from the sun) through photosynthesis during the making of food. This energy is then passed on from one organism to another in a food chain. Energy given out by the organisms as heat is lost to the environment, it does not return to be used by the plants again. This makes the flow of energy in ecosystem ‘unidirectional’. ecosystem is said to be unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis.

Ten Percent Law

• During the transfer of energy through successive trophic levels in an ecosystem, there is a loss of energy all along the path. No transfer of energy is 100 per cent. The studies of transfer of energy in different food chains in a large number of ecosystems has revealed a uniform pattern of transfer of energy, which is given by 10 per cent law. The 10 per cent law which was given by Lindeman in the year 1942, is one of the most useful generalisations about the magnitude of loss of energy in food chains.
• According to ten per cent law, only 10 per cent of the energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level. All the energy transfers in food chains follow the 10% law which in simple terms means that the energy available at each successive trophic level is 10 per cent of the previous level. Thus, there is a progressive decline (gradual reduction) in the amount of energy available as we go from producer level to the higher trophic levels of organisms.Let us take one example to understand the 10 per cent law more clearly.
• Suppose 1000 joules of light energy emitted by the sun falls on the plants (called producers). We know that the plants convert only one per cent (1%) of the light energy falling on them into chemical energy of food. So, the energy which will be available in plant matter as food will be only 1% of 1000 joules, which comes to 10 joules. The remaining 1000 – 10 = 990 joules of light energy or solar energy which is not utilized by the plants is reflected back into the environment . Please note that the ten per cent law will not apply at this stage. It will apply only in the transfer of energy in the food chain.
• We will now apply the 10 per cent law to the food chain : Plants-Herbivores -Carnivores . The plants or first trophic level has 10 joules of energy in it. Now, according to ten per cent law, only 10% of 10 joules of energy (which is 1 joule) will be available for transfer at the next trophic level, so that the herbivore (deer) will have only 1 joule of energy stored as food at the second trophic level . Applying the ten per cent law again we find that 10% of the remaining 1 joule (which is 0.1 joule) will be transferred to third trophic level of carnivore (lion). So, the energy available in the lion as food will be only 0.1 joule. We will now solve some problems based on ten per cent law.

Sample Problem 1. Calculate the amount of energy available to lion in the following food chain if plants have 20000 J of energy available from the sun :                                 Plants —–Deer ———Lion

1. Solution.  Plants can trap only 1% of the sun’s energy falling on them. Now, 1% of 20000 J is 200 J, so the plants have actually 200 J of energy available in them as food (The 10 per cent law does not apply at this stage).
2. The plants are eaten up by deer. Now, according to 10 per cent law, 10% of 200 J, that is, 20 J ofenergy will be available in deer as flesh food.
3. The deer will transfer 10% of its 20 J energy to the lion. Thus, the food energy available to the lionwill be 10% of 20 J which comes to 2 J.The above results can be shown more clearly as follows :

Sample Problem 2. Consider the following food chain :

Grass ————- Mice ————-Snakes ————Peacocks

If in this chain, 100 J of energy is available at the producer level, then calculate the energy transferred to the peacocks as food. State the law used in the calculations.

Solution. The producer level in this food chain is grass, so 100 J of energy is available in grass as food.

We have now to apply 10 per cent law to the above food chain :

1. According to ten per cent law, 10% of the energy of grass will be available as food in mice. Thus, the energy available to mice will be 10% of 100 J, which is 10 J.
2. The energy available to snakes will be 10% of 10 J which is 1 J.
3. And finally, the energy available to peacocks will be 10% of 1 J, which is 0.1 J.

The above conclusions can now be depicted as follows :

Why the Number of Trophic Levels in a Food Chain is Limited

• At each trophic level in a food chain, a large portion of the energy is utilized for the maintenance of organisms which occur at that trophic level and lost as heat. As a result of this, organisms in each trophic level pass on less and less energy to the next trophic levels, than they receive.
• The longer the food chain, the less is the energy available to the final member of food chain. Food chains generally consist of three or four steps (three or four organisms) because after that the energy available for the next organism will be so small that it will be insufficient to sustain the life of that organism.
• There are, however, some food chains containing five steps (or five organisms) but there are rarely more than five steps (or five organisms) in a food chain. We will now discuss the accumulation of harmful chemicals in food chains.

Accumulation of Harmful Chemicals in Food Chains

• The accumulation of harmful chemicals such as pesticides in the living organisms like plants, animals and humans (men) unknowingly, through the food chain, is called bioconcentration of pesticides. This happens as follows.
• Pesticides are poisonous chemical substances which are sprayed over crop plants to protect them from pests (harmful small animals) and diseases. These chemical pesticides mix up with soil and water.
• From soil and water, these pesticides are absorbed by the growing plants alongwith water and other minerals When herbivorous animals eat plant food, then these poisonous chemical pesticides go into their bodies hrough the food chain. And when the carnivorous animals eat herbivores, then the pesticides get transferred to their bodies. Man being an omnivore, eats plant food as well as herbivores.
• So, the pesticides present in plant food and herbivores also get transferred to the man’s body through food. Thus, pesticides enter the food chain at the producer level (plant level) and in the process of transfer of food through food chains these harmful chemicals get concentrated at each trophic level. The increase in concentration of harmful chemical substances like pesticides in the body of living organisms at each trophic level of a food chain is called biological magnification.
• Pesticides are non-biodegradable chemicals, so they get accumulated at each trophic level. Since humans occupy the top level in any food chain, so the maximum amount of harmful chemical pesticides gets accumulated in our bodies.
• This damages our health gradually. Tests have shown that the most commonly used pesticide DDT is accumulating in our bodies through the food chains. Please note that the pesticides present in our food grains (like wheat, rice), fruits, vegetables, and meat cannot always be removed by washing, etc. Let us solve one problem now.

Sample Problem. Which of the following will have the maximum concentration of harmful chemicals in its body ?

Peacock, Frog, Grass, Snake, Grasshopper

Solution. In order to answer such questions, we should first write the food chain involving the given organisms. The organism which occurs at the highest trophic level (on the extreme right side) in the food chain will have the maximum concentration of harmful chemicals in its body. In this case, grass is eaten by grasshopper; grasshopper is eaten by frog; frog is eaten by snake and finally snake is eaten by peacock. So,the food chain will be :

Grass ——– Grasshopper ——– Frog ——-Snake —- Peacock

In this food chain, since peacock occurs at the highest trophic level (on the extreme right side), therefore, peacock will have the maximum concentration of harmful chemicals in its body.

How do Our Activities Affect the Environment

We (human beings) are an important part of the environment. Our activities change the environment around us. And the changes in environment then affect us. We will now discuss two environmental problems caused by our activities : depletion of ozone layer, and disposal of domestic wastes (or household garbage).

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Depletion Of Ozone Layer

• We know that oxygen is O2. Oxygen molecule is made up of 2 atoms of oxygen combined together. Oxygen gas is essential for life because it is needed in respiration. Ozone is O3. Ozone molecule is made up of 3 atoms of oxygen combined together.
• Ozone is also a gas but it is poisonous in nature (if inhaled). Let us see how ozone is formed. Ozone is formed high up in the atmosphere by the action of ultraviolet radiation on oxygen gas. This happens as follows : The high energy ultraviolet radiation (UV radiation) coming from the sun splits oxygen gas into free oxygen atoms.

• The free oxygen atoms thus produced are very reactive. One oxygen atom reacts with an oxygen molecule to form an ozone molecule :

• At a height between 15 kilometres and 60 kilometres, there is a layer of ozone gas (O3) in the upper atmosphere. This ozone layer is very important for the existence of life on earth because it absorbs most of the harmful ultraviolet radiations coming from the sun and prevents them from reaching the earth. The ultraviolet radiations have extremely harmful effects on human beings, other animals as well as plants.
• For example, ultraviolet rays can cause skin cancer. They also damage the eyes by causing an eye disease called cataract. Ultraviolet rays damage immune system by lowering the body’s resistance to diseases.
• Thus, it is the ozone layer in the upper atmosphere which protects us from these diseases by absorbing ultraviolet rays coming from the sun.
• It has now been found that the amount of ozone is getting depleted (or reduced) due towhich the ozone layer in the upper atmosphere is becoming thinner and thinner day by day. The depletion of ozone layer is due to the use of chemicals called chlorofluorocarbons.
• This happens as follows : Chlorofluorocarbons (CFC) are the chemicals which are widely used in refrigeration (refrigerators and air conditioners) as a coolant; in fire extinguishers and in aerosol sprayers.
• Chlorofluorocarbons released into the air react with ozone gas present in the ozone layer and destroy it gradually. Due to this, the ozone layer in the upper atmosphere has become thinner, allowing more ultraviolet rays to pass through it to the earth.
• Thus, due to the depletion of ozone layer caused by chlorofluorocarbons, more ultraviolet radiations reach the earth.
• if the ozone layer in the atmosphere disappears completely, then all the extemely harmful ultraviolet radiations coming from the sun would reach the earth. These ultraviolet radiations would cause skin cancer
  and other ailments in men and animals, and also damage the plants. All the life on the earth would be destroyed gradually. In 1987, in an attempt to protect ozone layer, the United Nations Environment Programme (UNEP) forged an agreement among its member countries to freeze CFC production at 1986 levels.

KSEEB Class 10 SSLC Biology Chapter 5 Our Environment Managing The Garbage We Produce

The household wastes (or rubbish) is called garbage. Every household produces a lot of garbage (or wastes) daily. This garbage includes left-over food, fruit and vegetable peels, fallen leaves of potted plants, waste paper, unwanted plastic objects (such as plastic bottles, polythene bags, toys, etc.), glass articles (like glass bottles, broken window panes, etc.), metal objects (like aluminium foils, rusted iron grills, etc.), old wooden objects, rags (old, torn clothes), discarded shoes, and sewage. Some of the garbage (or waste) is biodegradable whereas a major part of it is non- biodegradable. If the household garbage or waste is not disposed of properly, it can pollute the environment like soil, water and air.

‘Disposal of waste’ means ‘to get rid of waste’. The disposal of waste should be done in a scientific way. There are different methods of waste disposal. The method to be used depends on the nature of the waste. Some of the important modes of waste disposal are.

1. Recycling
2. Preparation of compost
3. Incineration
4. Landfill
5. Sewage treatment

We will now describe all these methods of waste disposal (or garbage disposal) briefly, one by one. Let us start with recycling.

Recycling

The solid wastes like paper, plastics and metals, etc., are recycled. For example, waste paper is sent to paper mills where it is reprocessed to form new paper once again. The broken plastic articles like plastic bags, buckets, bowls, cups, plates, etc., are sent to plastic processing factories where they are melted and remoulded to make new articles. Similarly, waste metal articles are sent to metal industries where they are melted and recycled as solid metal for various purposes.

Preparation of Compost

Biodegradable domestic wastes such as left-over food, fruit and vegetable peels, and leaves of potted plants, etc., can be converted into compost by burying in a pit dug into ground, and used as manure.

Incineration

• ‘Incineration’ means ‘reducing to ashes’. The burning of a substance at high temperature (of more than 1000°C) to form ash is called incineration. Incineration is used to destroy household waste, chemical waste and biological waste (like that from hospitals).
• Incineration greatly reduces the volume of the waste. This is because when the large volume of waste material is burned, then only a small amount of ash is left behind which can be disposed of by landfill. Incineration is carried out in an incinerator (which is a kind of furnace).
• The waste disposal on large scale by using incinerators is done by the Municipality of a City. The solid waste is burned at a high temperature in the incinerator. All the organic matter present in waste is removed as carbon dioxide and water vapour. The ash left behind is removed from time to time.

Landfill

The disposal of wastes by putting it in low-lying areas of ground and covering it with earth is called landfill. Most of the solid waste in urban areas (which cannot be disposed of by other methods) is dumped in low-lying areas of ground and covered with earth to level the uneven ground. A big landfill site can be used to dispose of waste materials (or garbage) for a considerable time

Sewage Treatment

• The dirty drain water containing urine and faeces which is carried from our homes by the underground pipes (called sewers) is called sewage. If untreated sewage is dumped into a river, it can pollute the river water. Thus, sewage is disposed of by treating it at the sewage treatment plant (or sewage works).
• The treatment of sewage produces clean water which is discharged into the river. The organic matter present in sewage is ‘digested’ in the digesters of sewage treatment plant to produce ‘sewage gas’ (which is a kind of biogas), and ‘manure’.
• We will now give an example to illustrate how the use of biodegradable and non-biodegradable materials can make a difference to our environment. There was a time when tea in trains was served in plastic glasses which had to be returned to the vendor. This was, however, not a hygienic thing to do. Later on disposable plastic cups were introduced (which are used ‘once’ and then ‘thrown away’).
• Though it was hygienic to use a disposable plastic cup for drinking tea but the disposal of millions of plastic cups on daily basis posed a big problem. Sometime back ‘kulhads’ (disposable cups made of clay) were introduced for serving tea in trains.
• It was, however, soon realised that the use of a lot of clay for making millions of kulhads daily led to the loss of fertile top soil from fields (which was used for making kulhads). So, the practice of using ‘kulhads’ has also been discontinued. These days, disposable paper cups are being used.
• The use of disposable paper cups has the following advantages over the plastic cups :

1. Paper cups are biodegradable. So, even if paper cups are thrown away after use, they will decompose (break down) automatically by the action of micro-organisms in due course of time. On the other hand, plastic cups are non-biodegradable. They will remain as such and pollute the environment.
2. Paper cups can even be disposed of by burning without causing much air pollution. On the otherhand, burning of plastic cups produces toxic gases (poisonous gases) which cause too much airpollution.

KSEEB SSLC Class 10 Social Science Notes History

• Chapter 1 Advent of Europeans to India Notes
• Chapter 2 The Extension of the British Rule Notes
• Chapter 3 The Impact of British Rule in India Notes
• Chapter 4 Opposition to British Rule in Karnataka Notes
• Chapter 5 Social and Religious Reformation Movements Notes
• Chapter 6 The First War of Indian Independence (1857) Notes
• Chapter 7 Freedom Movement Notes
• Chapter 8 Era of Gandhi and National Movement Notes
• Chapter 9 Post Independent India Notes
• Chapter 10 The Political Developments of 20th Century Notes

KSEEB SSLC Class 10 Social Science Notes Political Science

• Chapter 1 The Problems of India and their Notes
• Chapter 2 Indian Foreign Policy Notes
• Chapter 3 India’s Relationship with Other Countries Notes
• Chapter 4 Global Problems and India’s Role Notes
• Chapter 5 International Institutions Notes

KSEEB SSLC Class 10 Social Science Notes Sociology

• Chapter 1 Social Stratification Notes
• Chapter 2 Labour Notes
• Chapter 3 Social Movements Notes
• Chapter 4 Social Problems Notes

KSEEB SSLC Class 10 Social Science Notes Geography

• Chapter 1 Indian Position and Extension Notes
• Chapter 2 Indian Physiography Notes
• Chapter 3 Indian Climate Notes
• Chapter 4 Indian Soils Notes
• Chapter 5 Indian Forest Resources Notes
• Chapter 6 Indian Water Resources Notes
• Chapter 7 Indian Land Resources Notes
• Chapter 8 Indian Mineral & Power Resources Notes
• Chapter 9 Indian Transport and Communication Notes
• Chapter 10 Indian Industries Notes
• Chapter 11 Indian Natural Disasters Notes
• Chapter 12 Indian Population Notes

KSEEB SSLC Class 10 Social Science Notes Economics

• Chapter 1 Development Notes
• Chapter 2 Rural Development Notes
• Chapter 3 Money and Credit Notes
• Chapter 4 Public Finance and Budget Notes

KSEEB SSLC Class 10 Social Science Notes Business Studies

• Chapter 1 Bank Transactions Notes
• Chapter 2 Entrepreneurship Notes
• Chapter 3 Globalization of Business Notes
• Chapter 4 Consumer Education and Protection Notes

KSEEB Solutions for Class 8 Geography Chapter 6 Human Resources Textbook Questions

Question 1. Answer the following questions:

(a)Why are people considered a resource?

Answer. People are a nations greatest resource as natural resources can be made useful and significant only when man applies his/her technical know-how. Human resource is the ultimate resource and it is called so by developing human skills. Resources are not, but they become by man.

(b)What are the causes for the uneven distribution of population in the world?

Answer. The causes for the uneven distribution in the world are:

1. Topography,
2. Climate,
3. Fertile soil,
4. Mineral deposits,
5. Water.

 (c) The world population has grown very rapidly. Why?

Answer. The world population is increasing very rapidly due to increase in the natural growth rate. Natural fed growth rate is the difference between the birth rate and the death rate of a country. With the  development in medical and health care services, the death rate has declined drastically,  although the birth rate is still high.

(d)Discuss the role of any two factors influencing population change.

Answer. The population change refers to change in the number of people during a specific time. The world population has not been stable. Two factors which influence population change are

1. Birth and death rate and Migration

Birth and death rate: Population change is the result of birth and death. The natural growth rate is the difference between the death rate and the birth rate of a country.
Migration: The other way in which population size changes is migration. It is a process in which people move out of a particular country or move to a different part of the same country. The people leaving the country are called Emigrants and the people who arrive in the country are called Immigrants.

(e)What is meant by population composition?

Answer. Population composition refers to the structure of the population. It helps to bring to light elements such as male-female ratio, age-group, literacy level, occupation, income levels and health conditions. In brief, population composition tells about almost each and every thing regarding population of a country.

 (f) What are population pyramids? How do they help in understanding about the population of a country?

Answer. Population pyramids, also called age-sex pyramids, are demographic structures based on the division of population of a country’ into different age groups.

1. Population pyramids help in understanding the various age groups, e.g., 5 to 9 years, 10 to 14 years etc.
2. They also help us in understanding the percentage of the total population, subdivided into males and females, in each of these groups.
3. It tells us how many dependents (young and elderly) are there in a country.
4. It also tells about birth and death rates.

Class 8 Geography KSEEB Chapter 6 Human Resources Notes 

Question 2. Tick the correct Answer:

(a)What does the term population distribution refer to?

1. How population in a specified area changes over time. 
2.  The number of people who die in relation to the number of people born in a specified area.
3. The way in which people are spread across a given area.

Answer. (3)

(b)Which are three main factors that cause population change?

1. Births, deaths and marriage
2.  Births, deaths and migration
3. Births, deaths and life expectancy.

Answer. (2)

(c)In 1999, the world population reached

(a) I billion (b) 3 billion    (c) 6 billion.

Answer. (c)

(d)What is a population pyramid?

(a)A graphical presentation of the age, sex composition of a population.

(b)When the population density of an area is so high that people live in tall buildings.

(c)Pattern of population distribution in large urban areas.

Answer. (a) 

Question 3. Complete the sentences below using some of the following words: sparsely, favourable, fallow, artificial, fertile, natural, extreme, densely, populated When people are attracted to an area it becomes populated.  Factors that influence this include climate; good supplies of resources and land.

Answer. When people are attracted to an area it becomes densely populated. Factors that influence this include favourable climate; good supplies of natural resources and fertile land.

KSEEB Class 8 Geography Solutions For Human Resources 

Human Resources Very Short Answer Type Questions

Question 1. What is the aim of Ministry of Human Resource Development?

Answer. The aim of Ministry of Human Resource Development is to improve people’s skills.

Question .2. Name the crowded areas of the world.

Answer. South Asia, South East Asia, Europe and North Eastern America.

Question .3. Which areas are sparsely populated?

Answer. High mountains, high latitude areas, tropical deserts and areas at equatorial forests are sparsely or less populated.

Question.4. In how many countries sixty per cent of the world’s people are staying?

Answer. In 10 countries, sixty per cent of the world’s people are staying.

Question .5. Which geographical factors affect the distribution of population?

Answer. Geographical factors affecting the distribution of population are:

1. tomography 
2. climate
3. Water
4. soil
5. minerals.

Question 6. What kind of people are the future of an nation?

Answer. Skilled, spirited and hopeful young people endowed with a positive outlook are the future of any nation.

Questions 7 Which parts of our country are moderately populated?

Answer The plateau of Deccan and Central India, large parts of Punjab, Haryana and Gujarat.

Question 8.  Which parts of India are most thickly populated?

Answer. Ganga and Brahmaputra Delta, the plains, the deltas of Mahanadi, Godavari, Krishna and Kaveri and the Malabar coastal strip.

Questions 9. Give three causes for high birth rate in India.

Answer

1. Early marriage.
2. Lack of education
3. Agricultural economy.

Questions 10. What is the main cause of high growth rate of the Indian population?

Answer. The widening gap between death rate and birth rate is the main cause of high rate of population growth.

Questions 11.What elements are included in the composition of population?

Answer Age, sex, literacy, occupation, language, religion, ethnicity, etc.

Questions 12  What is meant by sex composition?

Answer. It means the proportion of males and females in total population.

Questions 13 What is favourable and unfavourable sex ratio?

Answer. If sex ratio is more than 1000, it is favourable. If sex ratio is less than 1000, it is unfavourable.

Questions 14 What is the role of women in developing the country?

Answer. Women do household works, they help in the process of development and educate their children. Women train their children to become the future human resources.

Human Resources Class 8 KSEEB Questions And Answers 

Human Resources Short Answer Type Questions

Question 1 . Why is population considered a human resource?

Answer. Every human being is a potential resource for the country. People can use their skill to produce more. By providing education, training, nutritious food and health facilities people become a real resource.

Question 2. How is density of population measured?

Answer. The density of population is measured by taking the number of people living in per square kilometre of the surface area. India’s average population density is 382 persons per sq. km.

Question 3. ‘Plains occupy about half the world’s land surface but support more than 90% of world population’. Give reason.

Answer.

1. People always prefer plains for settling.
2. They can easily develop activities like farming, manufacturing and service activities.

Question 4. What is meant by dependent population?

Answer. Persons which do not contribute directly to any economic or productive activity are called dependent population. Generally, persons above 60 years and children below 15 years (0-14 age group) belong to this group. About 60% of India’s total population is dependent population.

Question 5. How does topography affect the distribution of population?

Answer. People always prefer to settle on plains because it is very easy to do farming, constructing and other developmental activities. These area are suitable for construction of roads, building factories. It is easy to live on plains rather than mountains. The Ganga-Brahmaputra plains are most densely populated areas of the world while mountains like Andes, Himalayas and Alps are thinly populated.

Question 6. How does soil affect the distribution of population?

Answer. Soil affects the distribution of population. The areas which have fertile soil has thick population because fertile soils provide suitable land for agriculture. So people like to live in such areas. The fertile plains of Ganga and Brahmaputra in India, Hwang-Ho, Chang Jiang in China and Niles in Egypt are densely populated.

Question .7. Water plays an important role in the distribution of population. Explain.

Answer. It is true that water plays an important role in the distribution of population. Early civilisations flourished in river valleys. People prefer to live in the areas where fresh water is easily available. The river valleys are densely populated while deserts have sparse population.

Question .8. The Government has to make efforts in providing health and education facilities to younger section of the population. Elucidate.

Answer. It has 34% of its population which lies in the younger age group, who have a great share in the working age group.

Explanation of Human Resources KSEEB Class 8 Geography 

Question 9. The sex ratio has been generally declining ever since 1901. Why?

Answer. In the Indian society, the female child is neglected. Male population dominates our society. There is high death rate among females. Death rate is particularly high among marred women. Due to such social evils present in the Indian society, sex ratio is declining. The sex ratio which was 972 in 1901 has been declined to 940 in 201 1.

Question 10.What factors control the distribution of population on the Earth?

Answer. The population is distributed unevenly. This is due to rugged topography and steep slopes. Low lying areas, desert areas, forests, plains and river valleys are densely populated. 90% of world population occupies only 30% area of land.

Question. 11 Distinguish between:

1. Birth rate and Growth rate.
   
2. Total population and Density of population.

Answer.

1.  Birth rate and Growth rate:                                                                                                                            Birth rate Growth rate
   (a) It is the number of people bom in a regior during a certain period of time.     (a) It is the rate at which the population grows in a region during a certain period of time.
   (b) It is calculated for every 1000 persons for a year.                                               (b) The growth rate of population is expressed in percentage during a certain period of time.
   (c) High birth rate shows an increasing population.                                                (c) When birth rate is more than death rate, it indicates a positive growth rate.
2. Total Population and Density of Population

Total Population                                                                                                                     Density of Population
(a) It is the number of people actually existing in the area.                                 (a) It is the number of people per unit area.
(b) It is counted during a census conducted after every 10 years.                       (b) The density of population in India was 382 per sq. km. in 2011.
(c) Total population of India was 121.02 crores in 201 1.                                      (c) It is expressed as average number of persons per sq. km. or mile.

Human Resources Long Answer Type Questions

Question 1 . What are the reasons for the rapid growth of population?

Answer.

1. In 1921, India’s population was 251 million while in 2011, it is over 1210 million. This ‘rapid growth of population is largely due to a fall in the number of deaths and an increase in the birth rate. New techniques of controlling or eradicating certain diseases also lower the death rates.
2. Another reason of population growth is migration. Population also increases when in-migration is more than out-migration. The growth rate of our population was 11 per cent between 1921 and 1931. But it became more than double to 24.7 per cent between 1971 and 1980. Today, we are the second most populated country in the world after China.

Question 2. What is the effect of rapid growth of population on the economic development of a country?

Answer.
Population growth has a great influence on the economic and social status of a country. It influences the gainful utilisation of the resources. In general, it has been observed that in the developed countries, the growth rate of population is low’. Thus, the standard of living is high. It is the reverse in under¬developed countries where most of the people are engaged in primary occupations, like agriculture and mining. They have a low standard of living.

Question.3. Name the moderately populated areas and give reasons for this.

Answer.

The areas whose population is mostly found between the densely populated regions and the sparsely populated regions are known as moderately populated areas. In these areas, facilities of irrigation and mining have improved. In some regions, new-‘ industries have developed. In these areas, favourable natural and economic factors attracted people from other regions. Deccan plateau of India, Eastern Europe, Central China, Tropical West Africa, Southern parts of Russia are some examples of moderate areas.

Question .4. What is population change?

Answer. When we compare the total population of a country in one year with another year, then we come to know about the population change-whether it has increased, decreased or is stable. This phenomenon is known as population change. For example, world’s population was just 100 million in 500 B.C.E and it became 900 million in 1800 C.E. In the next 150 years, it shot up to more than double i.e., 2500 million in 1950 CE. In the next 50 years, it again doubled as in 1999 rt was 6000 million (6 billion).

Free KSEEB Notes For Class 8 Geography Human Resources 

Question .5. What is a population pyramid? Explain the main features of the population pyramids of India, Japan and Kenya.

Answer.
Population pyramids are graphically drawn to show the age-sex composition of the population. Age group is shown on the vertical scale at 5-year intervals and the male-female population in millions is shown on the horizontal scale. The younger age group is shown at the base, while the older population is shown at the top. It is called a population pyramid because it rises in steps to a pointed top.

1. The main features of the population pyramids of India, Japan and Kenya are

1. Kenya: Being characterised by a high Birth Rate as well as a high Death Rate, Kenya is a developing country. A large number of children are bom, but most of them die in infancy due to the lack of medical services and comparatively a very a few survive till adulthood. Likewise, there are comparatively few old people. This is a  characteristics of the pyramid being cone¬shaped with a broad base and a narrowing top, as there are very few old people.
   
2. India: India is also a developing nation, but the economic status is better than that of Kenya. This is why, although the Birth Rate is high, the Death Rate is low on account of expanding health services and better nutrition. India’s Death Rate is declining which allows infants to survive till adulthood. This causes the population pyramid to be broad at the base and bulge in the middle. A large number of adult population means a strong and healthy work force.
   
3. Japan: Japan is a developed economy and hence has a Low Birth Rate and a Low Death Rate. Due to this fact, population pyramid is narrow at the base, expands in the middle and again becomes narrow on the top. A decrease in the Death Rate allows people to survive and reach old age.

Question .6. Describe the factors controlling the distribution of population.

Answer.

Distribution and Density: One of the important aspects of world’s population is its uneven distribution. The population depends upon the following factors Geographical Factors

1. Topography: It is one of the most important factors affecting the distribution of population. People always prefer plains rather than mountains and plateaus to settle because activities such as farming, manufacturing and service activities can easily be developed on plain regions. Plains occupy about half the world’s land surface but support more than 90% of the world’s population.
2. Climate: Regions having very hot or very cold climates are usually avoided by the people. That is why the equatorial parts of Africa and the polar regions of Russia, Canada and Antarctica have practically no population. Deserts also do not support people. Regions having temperate climate with moderate rainfall are densely populated. For example, countries of Eastern Asia and Western Europe.
3. Soil: Soil is the most important factor affecting agriculture. It helps us in obtaining food, clothing and shelter. Thus fertile plains such as those of the Ganga and Brahmaputra in India, the Hwang Ho and the Changjiang in China, and the Nile in Egypt are some of the densely populated areas.
4. Existence of Mineral Deposits: The discoveries of minerals in different parts of the world have attracted people. The diamond mines of South Africa and the discover)- of oil fields in the Middle-East are some examples.
5. Social and Economic Factors: Religious, cultural, industrial and commercial centres attract people from all over the world. Some of the cities in India such as Varanasi in Uttar Pradesh, Puri in Odisha, Kancheepuram in Tamil Nadu, Tirupati in Andhra Pardesh Vatican city and Jeruselum city are examples of religious centres. Cities such as Mumbai, Bengaluru, Kolkata, New York are some examples of industrial and commercial centres.

KSEEB Class 8 Geography Chapter 6 Important Questions 

Question.7. Give a reason of the unfavourable sex ratio in India.

Answer. Reasons for unfavourable sex ratio are:

1. Females are neglected.
2. Girls are killed just after birth, i.e., female infanticide.
3. Girl child is killed before birth and is called female foeticide.
4. Females d e as girl child due to negligence or deliberated attempts.
5. Women die at the time of child birth.

Question 8 Define the following:

Answer.

1. Birth Rate
2. Death Rate
3. Infant Mortality Rate
4. Life Expectancy
5. Natural Increase
6. Demographic Structure
   
7. Sex Ratio
8. Census.

1. Birth Rate is the number of live births in a year per 1000 of the population of an area. At present the birth rate in India is 20.97.
2. Death Rate is the number of deaths in a year per 1000 of the population of an area. At present, the death rate of India is 7.5.
3. Infant Mortality Rate is the number of deaths of children below one year of age per 1000 of population of an area.
4. Life Expectancy is the average at which people of a country die. It is at the age upto which most of the people of a country are expected to live. In India, the life expectancy is 67.5 years while in Britain it is 72 years.
5. Natural Increase is the difference of birth rate and death rate of country per 1000 of population. It shows excess of births over deaths. In India, the average natural increase has been 1.9 per year.
6. Demographic Structure is the division of population of a country into different groups and is shown by a pyramid. Age, sex structure is also shown in this way.
7. Sex Ratio is defined as the number of females per thousand males. In India, the sex ratio is 940.
8. The Census is the counting of population of a country. It takes place every ten years.

Human Resources Hots Corner

Question 1. Which social factors affect the distribution of population?

Answer.

1. Areas of better housing
2. education
3. health facilities.

Question 2. What do you mean by the pattern of population distribution?

Answer. The way in which people are spread across the earth surface is known as the pattern of population distribution.

Question 3. Which state in India has the largest population?

Answer.  According to 2011 census, Uttar Pradesh has :he largest population in India It has a total population of 19,95,81,477 persons. It is about 16.49% of India’s total population.

Question 4. Which state in India has the highest density of population?

Answer. The highest density’ of population in India is found in Bihar. It has density of 1, 102 persons per sq. km (2011).

Question 5. The equatorial parts of Africa and the polar regions of Russia, Canada have practically no population.

Answer. These regions have extreme climate. The equatorial parts of Africa are very hot and the polar regions are very cold. So practically, the population is very scarce in these regions.

Analysis of Human Resources in KSEEB Geography Class 8 

Question.6. Which areas of India have low density of population and why?

Answer. India’s hilly states of North and North-East have very low density of population. It is 86 in Sikkim, 119 in Nagaland, 124 in Jammu and Kashmir 132 in Meghalaya, 122 in Manipur, 17 in Arunachal, 52 in Mizoram and 123 in Himachal Pradesh. In these areas hilly terrain, low temperature, lack of meAnswer of trAnswerport and unfavourable climate have a great influence.

Question.7. What is age composition? Or Why is age composition important in the study of population?

Answer.  Age composition is very important in the study of population. If the children below 14 years are more, then the increase in population will be more in future. Migration of people also affects the age composition. If there are more people in the age group 0-14 years and above 65 years, then more people are dependent on the available resources.

Question.8. ‘Manpower is not assessed in terms of numbers alone’. Why?

Answer. Manpower is a vital resource of a country. It is the power w hich exploits the natural resources of a country. It must be educated, efficient, skilled and gifted with scientific knowledge. Healthy, educated, capable, hardworking and energetic people make the real manpower.

Question.9. ‘More people live in north of equator than in south of equator’. Justify.

Answer. Densely populated area of China. India, Asia, Cu’ope and North America are found in north of Equtator. But sparsely populated areas of South America, Africa, Australia are found in south of equator.

Question 10. Write a note on sex composition, age structure and literacy rate in the world with special reference to India.

Answer. Composition of Human Resources: The composition of human resources of a country includes age, sex, literacy, occupation, ethnicity, tribe, language and religion.

1. Sex Composition: This means the proportion of males and females in the total population. It is expressed with the help of sex ratio. Sex ratio is defined as the number of females per 1000 males in the population.
2. In India, the sex ratio is 940. For every 1000 males, there are only 940 females. Kerala and Pondicherry have sex ratio of 1084 and 1038 respectively.
3. Age Structure: The agewise distribution of people helps the government to plan for the people on various aspects. The population is divided into three age groups: (a) 0-4 year, (b) 15 64 years and (c) more than 65 years. India has 34% of ratio  population in the younger age group.
4. Literacy Rate: Literacy means the ability- to read, write and understand a simple message in the form of a language. If a person who is able to read but cannot write is considered as illiterate.
5. In India, a person is literate when he or she is aged 7 and above and is able to read, write and understand a simple statement in the farm of a language. At the time of Independence, only about one sixth of the population was literate. In 2011, 65% of the population was literate in India. In India more males are literates than females.

(a)High Literacy States: Kerala, Mizoram, Lakshadweep, Goa, Delhi, Chandigarh, Puducherry , Daman & Diu, Andaman & Nicobar Islands, Maharashtra, Himachal Pradesh and Tripura have high literacy.

(b)Low Literacy States: Bihar, Jharknand, Jammu & Kashmir, Arunachal Pradesh, Uttar Pradesh, Dadra & Nagar Haveli, Rajashtan, Andhra Pradesh, Meghalaya. Odisha, Madhya Pradesh, Assam are low literacy states.

Simplified Notes For Human Resources KSEEB Class 8 

Human Resources Map Based Questions

Question 1. Study the map given and Answer the following questions:

1. Which continent has very high annual rate of natural increase in population growth?Answer. Africa.
2. Name two continents which have low annual rate of natural increase in population growth.Answer. Europe, Australia.

Question.2. Study the chart given below and Answer the following questions:

1. Which is the world’s most popular country?
   Answer China
2. Which is the 2nd most populous country?
   Answer. India.
3. In the above chart, find out how many countries are in Asia.
   Answer. In the above chart, 6 countries-China, India, Indonesia, Pakistan, Bangladesh and Japan are in Asia.
4. Show the Software Technology Parks on the map of India.
   Answer.
   
   

Human Resources Miscellaneous Questions

A. Multiple Choice Questions Tick the correct option from the choices provided:

Question.1. What was the total population of world in 2011?
(a) 5 billion
(b) 6 billion
(c) 7 billion
(d) 8 billion

Answer. (c) 7 billion

Question.2. What was the total population of India in 2011?
(a) 100 crore
(b) 101 crore
(c) 121 crore
(d) 103 crore

Answer. (c) 121 crore

Question 3. What is the average density of population in world?
(a) 30 persons per sq. km.
(b) 35 persons per sq. km.
(c) 40 persons per sq. km.
(d) 45 persons per sq. km.          

Answer.
(d) 45 persons per sq. km.

KSEEB Solutions for Class 8 Geography Chapter 6 Human Resources PDF 

Question.4.What is the average density of population of India (per sq. km) in 2011;
(a) 310
(b) 315
(c) 370
(D)382

Answer.  (d) 382

Question.5. When was the Ministry of Human Resource Development established?
(a) In 1981
(b) In 1983
(c) In 1985
(d)In 1987

Answer.(c) in 1985

Question.6. Which of these is not a sparsely populated area?                           

(a) Deserts
(b) Forests
(c) Mountains
(D)Plains

Answer.(d) Plains

Question.7.How many countries have their population more than ten crores?                         

(a) Five
(b) Six
(c) Seven
(D)Ten

Answer. (d) Ten

Question.8. Which continent has only one per cent population of world?                               
(a) North America
(b) europe
(c) Asia
(d) Australia

Answer.  (d) Australia

Question.9. Which is densely populated area?
(a) Ganga plain
(b) Andes
(c) Alps
(D) Himalayan

Answer. (a) Ganga plain

Question 10. What is the cause of high growth rate of population?
 (a) High birth rate
(b) Low birth rate
(c) High death rate
(D)Low death rate

Answer. (d) Low death rate

B.One Word Sentence Answer

Answer the following questions in one word/sentence:

1. What is the average density of population in India?
   Answer. 382 persons per square Km.
2. How much population of the world is found on 10% land of world?
   Answer. 90%.
   
3. Which Indian state has the highest density of population?
   Answer. Bihar-1 102 persons.
4. Which Indian state has the lowest population density?
   Answer. Arunachal Pradesh-17 persons.
5. Which Indian state has the largest population?
   Answer. Uttar Pradesh-more than 20 crores.
6. What is the average density of population in the world?
   Answer. 45 persons per sq. km.
7. What is the total population of the world?
   Answer. More than 7 billion.
8. What was the total population of India in 2010?
   Answer. 121 crores.
9. Which year is known as “great divide” in the history of population of India?
   Answer. Year 1921.
10. What is the sex ratio of the world?
    Answer. 985 females per 1000 males.

Human Resources C.Fill in the Blanks

1.  ________________ is a country which has high population growth rate.
   
   Answer. Kenya
2. ___________________ministry looks after the education of us all.Answer. Human Resources Development
3. ___________and are the three characteristics of population which make human resource.Answer. Health, Education, Skill.
4. India ranks___________________in the world population.Answer. second after China
5. _____________is the number of years that an average person can expect to live.Answer. Life expectancy
6. The difference between the death rate and the birth rate of a country is called the .Answer. natural growth rate
7.  The number of live births per 1000 people is known asAnswer. birth rate
8. The number of deaths per 1000 people is known asAnswer. death ‘rate
9. _________is the movement of people in and out of an area.
   
   Answer. Migration
10. The difference between the birth rate and the death rate of a country is called
    the .Answer. natural growth rate
11. _____________is a country which have low population growth.Answer. United Kingdom
12. A person who arrives in a country is calledAnswer. immigrant
13. A person who leaves a country is calledAnswer. Emigrant

Class 8 Geography KSEEB Chapter 6 Human Resources notes 

Human Resources D.Picture Interpretation

Look at the following picture and Answer the questions that follow:

(i) Carefully read the diagram given below and explain the concept it is representing.

Answer. The chart shows the world population change though a demographic transition model.

Answer. The picture shows the decadal change in sex ratio in India.

KSEEB SSLC Class 9 Biology Notes Karnataka State Syllabus

• Chapter 1 The Fundamental Unit Of Life Notes
• Chapter 2 Tissues Notes
• Chapter 3 Diversity in Living Organisms Notes
• Chapter 4 Why Do We Fall ill Notes
• Chapter 5 Natural Resources Notes
• Chapter 6 Improvement In Food Resources Notes

KSEEB Class 10 SSLC Biology Chapter 1 Life Processes Notes

Something which is ‘living’ (not dead) is said to be ‘alive’. In most simple terms, ‘alive’ means ‘having life’.

Alive is called ‘jeevit’ or ‘zinda’ in Hindi. We are alive and you are also alive. Those things which are alive are called ‘living things’. All the plants and animals (including human beings) are alive or living things.

Now, an important question arises : What criteria do we use to decide whether something is alive? This is discussed below.

The most important criterion to decide whether something is alive (or not) is the movement. Movementis one of the most important signs of life in an organism. All the living things (which are alive) move by themselves without any external help.

In some cases the movements of living things are quite fast which can be easily observed by us but in other cases the movements are very slow and hence observed with difficulty. For example, the movements in most of the animals are fast and can be observed easily but

the movements in plants are usually slow and observed with difficulty. Animals and plants move in different ways. This will become clear from the following discussion.

Animals can move from one place to another or they can move their body parts. For example, a frog moves when it jumps into a pond, a bird moves when it flies in the sky, an athlete moves when he runs and a fish moves when it swims in water.

We move our hands when we clap and our chest moves up and down when we breathe. And a dog can wag its tail. All these movements show that a frog, bird, fish, dog and human beings are alive (or living things).

The plants are fixed in the soil at a place, so they cannot move like animals from place to place. The plants can only move parts of their body such as leaves, flowers, shoots and roots. The plant parts move towards a stimulus such as sunlight, gravity or water, etc.

For example, the shoot, the leaves and flower of a sunflower plant move by bending towards the sun so as to face the sunlight.

The leaves of a Mimosa pudica plant (sensitive plant) move by folding up when touched with a finger. Plants also show movement by growing their roots and shoots bigger.

 Non-living things (which are not alive) cannot move by themselves. For example, a stone is a non-living thing which cannot move by itself from one place to another or show any other type of movement. We will have to move it by applying force from outside.

All the living things (plants and animals) are made up of tiny living units called cells. The cells themselves are made up of still smaller particles called molecules. The movements over very small scale (as those in the molecules of living things) are invisible to the naked eye.

The invisible molecular movement is, however, necessary for the existence of life. In fact, viruses do not show any molecular movement in them (until they infect some cell) and this has created controversy about whether they are truly alive or not. In addition to movement, the living things also show some other characteristics.

These are discussed below.

All the living things (which are alive) have some common characteristics (or features) which make them different from non-living things. The characteristics of living things are as follows:

1. Living things can move by themselves.
2. Living things need food, air and water.
3. Living things can grow.
4. Living things respire (release energy from food).
5. Living things excrete (get rid of waste materials from their body).
6. Living things can reproduce. They can have young ones.

KSEEB Class 10 SSLC Biology What Are Life Processes

All the organisms perform some basic functions to keep themselves alive. The basic functions performed by living organisms to maintain their life on this earth are called life processes.

The basic life processes common to all the living organisms are: Nutrition and Respiration; Transport and Excretion; Control and Coordination (Response to stimuli); Growth; Movement and Reproduction.

• The process of nutrition involves the taking of food inside the body and converting it into smaller molecules which can be absorbed by the body.
• Respiration is the process which releases energy from the food absorbed by the body. Transport is the process in which a substance absorbed or made in one part of the body is moved to other parts of the body.
• Excretion is the process in which the waste materials produced in the cells of the body are removed from the body.
• Control and coordination (or response to stimuli) is a process which helps the living organisms to survive in the changing environment around them.
• The process of growth involves the change from a small organism to a big organism (or an adult organism). In movement, the organism either moves from one place to another or moves its body parts while remaining at the same place.
• The process of reproduction involves the making of more organisms from the existing ones, so that organisms could live on this earth for ever.

KSEEB Class 10 SSLC Biology Energy is Needed for the Life Processes

• All the living organisms need energy to perform various life processes. They get this energy from food.
• Food is a kind of fuel which provides energy to all the living organisms. The living organisms use the chemical energy for carrying out various life processes. They get this chemical energy from food through chemical reactions.
• Actually, living organisms continuously need energy for their various life processes and other activities which they perform. For example, energy is required by an organism even during sleep. This is because when we are asleep, a number of biological processes keep on occurring in the body which require energy.
• Our heart beats non-stop even when we are asleep to pump blood throughout the body. And this beating of heart requires energy. Thus, the working of heart requires a continuous supply of energy.
• The energy required by an organism comes from the food that the organism eats. Thus, food is the basic requirement of all the living organisms for obtaining energy.
• In this chapter we will first study the process of intake and utilisation of the food by an organism (called nutrition) and the liberation of energy from the food (called respiration).
• After that we will study the process of moving the digested food and other materials to the various parts of the body (called transport) and the removal of waste materials from the body (called excretion). Let us start with nutrition.

KSEEB Class 10 SSLC Biology Nutrition

Food is an organic substance. The simplest food is glucose. It is also called simple sugar. A more complex  food is starch. Starch is made from glucose. The general name of substances like glucose (sugar) and starch is ‘carbohydrates’.

• Carbohydrates are the most common foods for getting energy. Fats and proteins are also foods. (A wider definition of food, however, also includes mineral salts, vitamins and water which are essential for the normal growth and development of an organism).
• The process of taking in food (consuming food) and utilising it is called nutrition. It is a process in which food is obtained in order to utilise it to provide energy for performing various metabolic activities of the organism.
• Actually, the term ‘nutrition’ comes from the word ‘nutrient’. A nutrient is an organic or inorganic substance required for the maintenance of life and survival of a living organism. In most simple terms, a nutrient can be said to be a particular type of food.
• A nutrient can be defined as a substance which an organism obtains from its surroundings and uses it as a source of energy or for the biosynthesis of its body constituents (like tissues and organs).
• For example, carbohydrates and fats are the nutrients which are used by an organism mainly as a source of energy whereas proteins and mineral salts are nutrients used by an organism for the biosynthesis of its body constituents like skin, blood, etc.
• The food taken in by an organism contains a large number of nutrients like carbohydrates, fats, proteins, minerals, vitamins and water, etc.
• We can now say that: Nutrition is a process of intake of nutrients (like carbohydrates, fats, proteins, minerals, vitamins and water) by an organism as well as the utilisation of these nutrients by the organism.
• We will now describe the various ways of procuring food (or obtaining food) by the different organisms. In other words, we will now describe the different modes of nutrition of the various organisms.

KSEEB Class 10 SSLC Biology Modes Of Nutrition

Modes of nutrition means methods of procuring food or obtaining food by an organism. All the organisms do not obtain their food in the same way. Different organisms have different methods of procuring food or obtaining food. In other words, organisms differ in their modes of nutrition. Depending on the mode (or method) of obtaining food, all the organisms can be classified into two groups:  autotrophic and heterotrophic. Thus: There are mainly two modes of nutrition :

1. Autotrophic, and
2. Heterotrophic.

We will now discuss the autotrophic mode of nutrition and the heterotrophic mode of nutrition in detail, one by one.

KSEEB Class 10 SSLC Biology Autotrophic Mode Of Nutrition

The word ‘auto’ means ‘self’ and ‘trophe’ means ‘nutrition’. Thus, autotrophic means ‘self nutrition’. In autotrophic nutrition, the organism makes (or synthesizes) its own food from the inorganic raw materials like carbon dioxide and water present in the surroundings by using the sunlight energy. We can now say that : Autotrophic nutrition is that mode of nutrition in which an organism makes (or synthesizes) its own food from the simple inorganic materials like carbon dioxide and water present in the surroundings (with the help of sunlight energy). Please note that food is an organic material (like glucose, etc.).

•  This means that, in autotrophic nutrition, organic material (food) is made (or synthesized) from inorganic materials like carbon dioxide and water by utilizing the sunlight energy.
• The green plants have an autotrophic mode of nutrition. The autotrophic bacteria also obtain their food by the autotrophic mode of nutrition (though most bacteria are not autotrophic).
• The organisms having autotrophic mode of nutrition are called autotrophic organisms or just autotrophs.
• Those organisms which can make their own food from carbon dioxide and water are called autotrophs. Carbon dioxide and water are inorganic substances. So, we can also say that: Those organisms which can make their own food from the inorganic substances present in the environment, are called autotrophs.
• All the green plants are autotrophs (because they can make their own food from inorganic substances like carbon dioxide and water present in the environment). Non-green plants are, however, not autotrophs. Certain bacteria called ‘autotrophic bacteria’ are also autotrophs.

• The autotrophic organisms (or autotrophs) contain the green pigment called chlorophyll which is capable of trapping sunlight energy. This trapped sunlight energy is utilised by the autotrophs to make food by combining inorganic materials like carbon dioxide and water present in the environment by the process of photosynthesis.
• Thus, autotrophs make their own food by photosynthesis. So, autotrophs are the producers of food. The food produced by autotrophs (green plants) is also used by human beings and many, many other animals.

KSEEB Class 10 SSLC Biology Heterotrophic Mode of Nutrition

The word ‘heteros’ means ‘others’ and ‘trophe’ refers to ‘nutrition’. Thus, ‘heterotrophic’ means ‘nutrition obtained from others’. In heterotrophic nutrition, the organism cannot make (or synthesize) its own food from the inorganic raw materials like carbon dioxide and water, and uses the food made by autotrophic organisms directly or indirectly.

We can now say that:

• Heterotrophic nutrition is that mode of nutrition in which an organism cannot make (or synthesize) its own food from simple inorganic materials like carbon dioxide and water, and depends on other organisms for its food.
• A heterotrophic organism is a consumer which derives its nutrition from other organisms. That is, a heterotrophic organism has to eat other organisms for its nutrition.
• All the animals have a heterotrophic mode of nutrition. Most bacteria and fungi also have heterotrophic mode of nutrition.
• The organisms having heterotrophic mode of nutrition are called heterotrophic organisms or just heterotrophs.
• Those organisms which cannot make their own food from inorganic substances like carbon dioxideand water, and depend on other organisms for their food are called heterotrophs.
• All the animals are heterotrophs (because they cannot make food from inorganic substances like carbon dioxide and water and obtain their food from other plants or animals.). Thus, man, dog, cat, deer, tiger, bear, lion, cow, etc., are all heterotrophs.
• The non-green plants (like yeast) are also heterotrophs.
• Heterotrophs depend on autotrophs and other heterotrophs for their food. In other words, animals are heterotrophs which depend on plants or other animals for their food.
• From the above discussion we conclude that green plants make their own food. Non-green plants and animals cannot make their own food. They obtain food from plants and other animals. We will now discuss the various types of the heterotrophic mode of nutrition.

KSEEB Class 10 SSLC Biology Types Of Heterotrophic Nutrition

A heterotrophic organism (or heterotroph) can obtain its food from other organisms in three ways. So, the heterotrophic mode of nutrition is of three types:

1. Saprotrophic nutrition,
2. Parasitic nutrition, and
3. Holozoic nutrition.

We will now discuss the three types of heterotrophic nutrition in detail, one by one. Let us start with the saprotrophic nutrition.

KSEEB Class 10 SSLC Biology Saprotrophic Nutrition (or Saprophytic Nutrition)

Saprotrophic nutrition is that nutrition in which an organism obtains its food from decaying organic matter of dead plants, dead animals and rotten bread, etc.

• ‘Sapro’ means ‘rotten’, so a saprotrophic organism draws its food from rotting wood of dead and decaying trees, rotten leaves, dead animals and household wastes like rotten bread, etc. The organisms having saprotrophic mode of nutrition are called saprophytes.
• We can now say that  : Saprophytes are the organisms which obtain their food from dead plants (like rotten leaves), dead and decaying animal bodies, and other decaying organic matter (like rotten bread).

• Fungi (like bread moulds, mushrooms, yeast), and many bacteria are saprophytes. We know that fungi and bacteria are a kind of plants. So, we can also say that saprophytes are the plants which feed on dead and decaying organic matter.
• The saprophytes break down the complex organic molecules present in dead and decaying matter and convert them into simpler substances outside their body. These simpler substances are then absorbed by saprophytes as their food. Please note that saprotrophic nutrition is also known as saprophytic nutrition.

KSEEB Class 10 SSLC Biolog

Parasitic Nutrition

• The parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism (called its host) without killing it. The organism which obtains the food is called a ‘parasite’, and the organism from whose body food is obtained is called the ‘host’.
• We can now say that: A parasite is an organism (plant or animal) which feeds on another living organism called its host. A parasite receives its food from the host but gives no benefit to the host in return. A parasite usually harms the host. The host may be a plant or an animal.

• Most of the diseases which affect mankind, his domestic animals (like dogs and cattle) and his crops are caused by parasites. Parasitic mode of nutrition is observed in several fungi, bacteria, a few plants like Cuscuta (amarbel) and some animals like Plasmodium and roundworms.
• Thus, the micro-organism ‘Plasmodium’ (which causes malaria disease) is a parasite. Roundworm which causes diseases in man and domestic animals (like dogs and cattle) is also a parasite.
• Roundworms live inside the body of man and his domestic animals. Several fungi and bacteria, and plants like Cuscuta (amarbel) are also parasites. Some other examples of parasites are ticks, lice, leeches and tapeworms.

KSEEB Class 10 SSLC Biology Holozoic Nutrition

‘Holozoic nutrition’ means ‘feeding on solid food’ (which may be a plant product or an animal product). Most of the animals (including human beings) take the solid food into their body by the process of ingestion.

• The ingested food is then digested (broken down) into simpler substances which are then absorbed into the cells of the body. And the undigested and unabsorbed waste materials are egested (thrown out) of the body.
• We can now say that : The holozoic nutrition is that nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion, the ingested food is digested and then absorbed into the body cells of the organism.
• The undigested and unabsorbed part of the food is thrown out of the body of the organism by the process of egestion.
• The human beings and most of the animals have a holozoic mode of nutrition. In other words, man, cat, dog, cattle, deer, tiger, lion, bear, giraffe, frog, fish and Amoeba, etc., have the holozoic mode of nutrition.

KSEEB Class 10 SSLC Biology Nutrition In Plants

• Just like other organisms, plants also require food which can supply energy for their various metabolic activities. Though animals can move from one place to another in search of food, plants just stand still at one place and make their own food.

• Green plants are autotrophic and synthesize their own food by the process of photosynthesis. ‘Photo’ means ‘light’ and ‘synthesis’ means ‘to build’, thus ‘photosynthesis’ means ‘building up by light’.
• The plants use the energy in sunlight to prepare food from carbon dioxide and water in the presence of chlorophyll. Chlorophyll is present in the green coloured bodies called ‘chloroplasts’ inside the plant cells.
• In fact, the leaves of a plant are green because they contain tiny green coloured organelles called chloroplasts (which contain chlorophyll).
• Keeping these points in mind, we can now define the process of photosynthesis as follows: The process by which green plants make their own food (like glucose) from carbon dioxide and water by using sunlight energy in the presence of chlorophyll, is called photosynthesis. Oxygen gas is released during photosynthesis. The process of photosynthesis can be represented as:

• The process of photosynthesis takes place in the green leaves of a plant. In other words, food is made in the green leaves of the plant. The green leaves of a plant make the food by combining carbon dioxide and water in the presence of sunlight and chlorophyll.
• The carbon dioxide gas required for making food is taken by the plant leaves from the air. This carbon dioxide enters the leaves through tiny pores in them called stomata.Water required for making food is taken from the soil.
• This water is transported to the leaves from the soil through the roots and stem. The sunlight provides energy required to carry out the chemical reactions involved in the preparation of food.
• The green pigment called chlorophyll present in green leaves helps in absorbing energy from sunlight.
• Oxygen gas is produced as a by-product during the preparation of food by photosynthesis. This oxygen gas goes into the air
• The food prepared by the green leaves of a plant is in the form of a simple sugar called glucose. This glucose food made in the leaves is then sent to the different parts of the plant .
• The extra glucose is changed into another food called starch. This starch is stored in the leaves of the plant. Glucose and starch belong to a category of foods called carbohydrates.
• The foods like carbohydrates prepared by photosynthesis contain chemical energy stored in them. Thus, the green plants convert sunlight energy into chemical energy by making
• All these food items have been made by the plants by the process of photosynthesis. carbohydrates (foods). The food prepared by photosynthesis provides all the energy to a plant which it needs to grow.
• And when we eat plant foods (like foodgrains, fruits and vegetables), the chemical energy stored in them is released in our body during respiration.

We will now describe what actually happens during the process of photosynthesis. The photosynthesis takes place in the following three steps:

1. Absorption of sunlight energy by chlorophyll.
2. Conversion of light energy into chemical energy, and splitting of water into hydrogen and oxygen by light energy.
3. Reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by utilising the chemical energy (obtained by the transformation of light energy).

Please note that the three steps involved in photosynthesis need not take place one after the other immediately. They can take place at different times.

• For example, desert plants take up carbon dioxide at night and prepare an intermediate product which is acted upon by the sunlight energy absorbed by chlorophyll when the sun shines during the next day.

KSEEB Class 10 SSLC Biology Conditions Necessary For Photosynthesis.

• It has been found by experiments that the presence of sunlight, chlorophyll, carbon dioxide and water is necessary for the process of photosynthesis. So, we can say that: The conditions necessary for photosynthesis to take place are:

1. Sunlight,
2. Chlorophyll,
3. Carbon dioxide, and
4. Water.

• Please note that the conditions necessary for photosynthesis are also the conditions necessary for autotrophic nutrition. We will now describe some experiments to show that sunlight, chlorophyll and carbon dioxide are necessary for photosynthesis by green plants.
• These experiments will also show that leaves finally make ‘starch’ as food by photosynthesis.
• The experiments on photosynthesis depend on the fact that green leaves make starch as food. And that starch gives a blue-black colour with iodine solution.
• Now, ordinarily all the plants have starch in their green leaves, so before we can use a plant in a photosynthesis experiment, the initial starch present in its leaves must be removed.
• In other words, we should destarch the leaves of a plant before using it in a photosynthesis experiment. The green leaves of a plant are destarched by keeping this plant in a completely dark place in a room for at least three days.
• When the plant is kept in a dark place, it cannot make more starch (food) by photosynthesis because there is no sunlight. So, the plant kept in dark place uses the starch already stored in its leaves during respiration.
• The plant will use up all the starch stored in its leaves in about three days’ time. So, after about three days, the plant leaves will not have any starch left in them.
• And we say that the leaves have been destarched. This plant with destarched leaves can now be used in the photosynthesis experiments.
• Please note that we will be using a plant growing in a pot in these experiments. The ‘plant growing in a pot’ is called ‘potted plant’. Let us describe the experiments now

KSEEB Class 10 SSLC Biology Experiment To Show That Sunlight Is Necessary For Photosynthesis

1. We take a potted plant having green leaves and place it in a completely dark place for about three days to destarch its leaves. So, in the beginning of the experiment, the leaves do not have any starch in them.
2. Take a thin strip of aluminium foil (or black paper) and wrap it in the centre of one leaf on both the sides (while the leaf is still attached to the plant. The aluminium foil should be fixed tightly to the leaf by using paper clips so that sunlight may not enter it from the sides. The aluminium foil should cover only a small part of the leaf so that the remaining part of the leaf remains uncovered and exposed to sunlight. We have covered the centre part of the leaf with aluminium foil so that sunlight may not fall on this covered part of the leaf.
3. Keep this potted plant (with partially covered leaf) in bright sunshine for three to four days.
4. Pluck the partially covered leaf from the plant and remove its aluminium foil. Immerse this leaf in boiling water for a few minutes. This will break down the cell membranes of leaf cells and make the leaf more permeable to iodine solution (so that it may reach the starch present inside the leaf cells).                                                                                                               
5. This leaf is now to be tested for the presence of starch. But before testing for starch, chlorophyll has to be removed from the leaf. This is because chlorophyll interferes in the test for starch due to its green colour.
6. Put the plucked leaf in a beaker containing some alcohol. Place the beaker containing alcohol and leaf in a water bath (A water bath can be a bigger beaker containing water.
7. Heat the water in the bigger beaker (or water bath). Then the alcohol in the smaller beaker will also get heated and start boiling soon. This boiling alcohol will extract (or remove) chlorophyll from the green leaf.
8. Boil the green leaf in alcohol till all its green pigment ‘chlorophyll’ is removed. The leaf will now become almost colourless or pale (and the alcohol will turn green).
9. Remove the colourless leaf from alcohol and wash it thoroughly with hot water to soften it and remove any chlorophyll which may be sticking to it.
10. Place the colourless leaf in a petri-dish Drop iodine solution over the decolourised leaf with the help of a dropper. Observe the change in colour of leaf.
11. The middle part of leaf which was covered with aluminium foil does not turn blue-black on adding iodine solution showing that no starch is present in this middle part of the leaf.
12. This is because sunlight could not reach the covered ‘middle part of the leaf due to which the covered ‘middle part’ of leaf could not do photosynthesis to make starch.
13. The uncovered part of leaf (on both sides of the aluminium foil) which was exposed to sunlight turns blue-black on adding iodine solution showing that starch is present in this part of leaf .
14. This means that the part of leaf which was exposed to sunlight could do photosynthesis to make starch.
15. Since the part of leaf which was covered and hidden from sunlight does not contain starch but the
16. part of leaf which was exposed to sunlight contains starch, therefore, we conclude that sunlight is necessary for photosynthesis (to make food like starch).
17. From the above experiment, we actually get two conclusions. That :
18. sunlight is necessary for the process of photosynthesis, and
19. leaves make starch as food by photosynthesis.
20. Most of the common plants have leaves which are totally green (because all the parts of such leaves contain the green pigment called chlorophyll).
21. But there are some plants whose leaves are partly green and partly white. The green part of such a leaf contains chlorophyll but the white part of such a leaf does not contain chlorophyll.
22. The leaves which are partly green and partly white are called ‘variegated leaves’. The plants such as croton and Coleus have variegated leaves which are partly green and partly white.

We will use a plant having variegated leaves in the next experiment to show that chlorophyll is necessary for the process of photosynthesis in plants.

KSEEB Class 10 SSLC Biology Experiment To Show That Chlorophyll Is Necessary For Photosynthesis

1. We take a potted plant like croton whose leaves are partly green and partly white .The green part of the leaf has chlorophyll but the white part of the leaf does not have chlorophyll.
2. Place this plant in a completely dark place for about three days to destarch its leaves.
3. Take out the potted plant from the dark place and keep it in bright sunshine for three to four days.

8. Pluck the variegated leaf from the plant, boil it in water for a few minutes and then remove its green colour ‘chlorophyll’ by boiling it in alcohol. The green parts of the leaf get decolourised. So, we get decolourised leaf
9. Wash the decolourised leaf with hot water to soften it and remove any chlorophyll which may be sticking to it.
10. Pour iodine solution over the colourless leaf and observe the change in colour of the leaf.
11. We will find that the outer part of leaf that was originally white (without chlorophyll) does not turn blue-black on adding iodine solution showing that no starch is present in this outer part of the leaf From this observation we conclude that the photosynthesis to make starch does not take place without chlorophyll.
12. The inner part of leaf which was originally green (contained chlorophyll) turns blue-black on adding iodine solution showing that starch is present in this inner part of the leaf.From this observation we conclude that the photosynthesis to make starch takes place in the presence of chlorophyll. In other words, chlorophyll is necessary for the process of photosynthesis to take place.

KSEEB Class 10 SSLC Biology Experiment To Show That Carbon Dioxide Is Necessary For Photosynthesis

1. We take a potted plant having long and narrow leaves and place it in a completely dark place for about three days to destarch its leaves.
2. Take a glass bottle having a wide mouth and put some potassium hydroxide solution (KOH solution) in it. (This potassium hydroxide solution is to absorb the carbon dioxide gas from the air present in the glass bottle so that no carbon dioxide is left in the air inside the glass bottle).
3. Take a rubber cork which fits tightly into the mouth of the glass bottle and cut it into two halves.
4. Put a destarched leaf of the potted plant (while it is still attached to the plant), in-between the two halves of the cut cork and then fit the cork in the mouth of the glass bottle. The upper half of the leaf should remain outside the glass bottle and only the lower half of the leaf should be inside the glass bottle
5. The potted plant (with its one destarched leaf half inside the glass bottle containing potassium hydroxide solution) is kept in sunlight for 3 to 4 days. During this period, the upper half of the leaf (which is outside the glass bottle) gets carbon dioxide from the air but the lower half of the leaf (which is inside the glass bottle) does not get any carbon dioxide. This is because all the carbon dioxide of the air present in the glass bottle has been absorbed by potassium hydroxide solution.And no fresh air can come into the closed glass bottle. Carbon dioxide available here No carbon dioxide Potassium hydroxide solution (to absorb carbon dioxide)
6. 
7. Pluck the leaf from the plant and take it out from the glass bottle. Remove the green coloured chlorophyll from the leaf by boiling it in alcohol. In this way, we get a decolourised leaf.
8. Wash the decolourised leaf with water to remove any chlorophyll which may be sticking to it.
9. Pour iodine solution over the colourless leaf and observe the change in colour of the leaf.
10. We will find that the lower half part of the leaf (which was inside the glass bottle having no carbon dioxide around it), does not turn blue-black on adding iodine solution showing that no starch is present in this lower half of the leaf [see Figure 20(c)]. From this observation we conclude that the photosynthesis to make starch in the leaf does not take place without carbon dioxide.
11. The upper half part of the leaf (which was outside the glass bottle, having carbon dioxide around it) turns blue-black on adding iodine solution showing that starch is present in this upper half of the leaf. From this observation we conclude that photosynthesis (to make starch) takes place in the presence of carbon dioxide. In other words, carbon dioxide is necessary for the process of photosynthesis to take place.

KSEEB Class 10 SSLC Biology Raw Materials For Photosynthesis

The preparation of carbohydrates (food) by plants by the process of photosynthesis requires two materials (or substances) : carbon dioxide, and water. Thus, the raw materials for photosynthesis are:

• Carbon dioxide, and
• water

We will now describe how these two raw materials become available to plants for photosynthesis.

KSEEB Class 10 SSLC Biology How The Plants Obtain Carbon Dioxide

There are a large number of tiny pores called stomata on the surface of the leaves of plants (The singular of stomata is stoma). The green plants take carbon dioxide from air for photosynthesis. The carbon dioxide gas enters the leaves of the plant through the stomata present on their surface .

• Each stomatal pore (or stoma) is surrounded by a pair of guard cells. The opening and closing of stomatal
• Chloroplast Surface of a leaf Guard cells (curved) Open stoma Guard cells (straight) Closed stoma

1. Open stomata
2. Closed stomata

• The plants take carbon dioxide required for photosynthesis from air through the stomata (tiny pores) present on the surface of a leaf. pores is controlled by the guard cells.
• When water flows into the guard cells, they swell, become curved and cause the pore to open .On the other hand, when the guard cells lose water, they shrink, become straight and close the stomatal pore.
• A large amount of water is also lost from the cells of the plant leaves through open stomatal pores. So, when the plant does not need carbon dioxide and wants to conserve water, the stomatal pores are closed. The oxygen gas produced during photosynthesis also goes out through the stomatal pores of the leaves.
• Please note that in addition to leaves, the stomata are also present in the green stems (or shoots) of a plant. So, the green stems (or shoots) of a plant also carry out photosynthesis. It is clear from the above discussion that stomata allow the movement of gases in and out of plant cells. In other words, the gaseous exchange in plants takes place through the stomata in leaves (and other green parts).
• Please note that in most broad-leaved plants, the stomata occur only in the lower surface of the leaf but in narrow-leaved plants, the stomata are equally distributed on both the sides of the leaf. Another point to be noted is that the aquatic plants (or water plants) use the carbon dioxide gas dissolved in water for carrying out photosynthesis.
• The stomata on the lower surface of a leaf as seen through a microscope.

KSEEB Class 10 SSLC Biology How The Plants Obtain Water For Photosynthesis

• The water required by the plants for photosynthesis is absorbed by the roots of the plants from the soil through the process of osmosis. The water absorbed by the roots of the plants is transported upward through the xylem vessels to the leaves where it reaches the photosynthetic cells and utilised in photosynthesis.
• The two raw materials, carbon dioxide and water, are required by the plants to prepare energy foods called carbohydrates (such as glucose and starch). But the plants also need other raw materials such as nitrogen, phosphorus, iron and magnesium, etc., for building their body.
• The plants take materials like nitrogen, phosphorus, iron and magnesium, etc., from the soil. For example, nitrogen is an essential element used by the plants to make proteins and other compounds.
• The plants take up nitrogen from the soil in the form of inorganic salts called nitrates (or nitrites), or in the form of organic compounds which are produced by bacteria from the atmospheric nitrogen.

KSEEB Class 10 SSLC Biology Site Of Photosynthesis Chloroplasts

• Chloroplasts are the organelles in the cells of green plants which contain chlorophyll and where photosynthesis takes place. Thus, photosynthesis occurs in the organelles called chloroplasts present in the photosynthetic cells (or mesophyll cells) of green plants.
• In other words, the site of photosynthesis in a cell of the leaf are chloroplasts. Chloroplasts can be seen easily by using a light microscope. In a cross- section of a leaf, chloroplasts can be seen as numerous disc-like organelles in the photosynthetic cells (or mesophyll cells) of the palisade tissue just below the upper epidermis

• Cuticle Photosynthetic tissue (Mesophy) Upper epidermis Palisade layer Chloroplasts Spongy- layer Lower epidermis.
• Water required for photosynthesis is absorbed by the roots of the plants from the soil.
• Air spaces Stoma Guard calls. The structure of a leaf to show chloroplasts in it (The small green circles in the above diagram are all chloroplasts).
• In the structure of a leaf we can see that the middle layers in the leaf (palisade layer and spongy layer) contain photosynthetic cells called mesophyll cells.
• These cells contain more chlorophyll than other plant cells. A typical photosynthetic cell (or mesophyll cell) of a green leaf may contain 100 or more tiny chloroplasts in it, and a whole leaf may contain many thousands of photosynthetic cells.
• Carbon dioxide needed for photosynthesis enters from the air into the leaf through the stomata in its surface and then diffuses into the mesophyll cells and reaches the chloroplasts.
• Water is carried to the leaf by xylem vessels and passes into the mesophyll cells by diffusion and reaches the chloroplasts.
• There is a thin, waxy protective layer called cuticle above and below a leaf which helps to reduce the loss of water from the leaf.

KSEEB Class 10 SSLC Biology Nutrition in Animals

• We have just studied the nutrition in plants. We have learnt that plants are autotrophic organisms which can manufacture their own food.
• So, plants don’t have to look to others for getting their food. They are food producers themselves. But this is not so in the case of animals.
• Animals are heterotrophs and hence they depend on other organisms for their food. Thus, animals need an external source of food. We will now discuss how animals obtain their food.

KSEEB Class 10 SSLC Biology Animals Obtain Their Food From Plants Or Other Animals

• Since animals cannot make their own food, they depend on readymade food.
• This readymade food comes either from ‘plants’ or from ‘other animals’. Thus, animals obtain their food from plants or other animals (which they eat). We (human beings) are also animals.
• We obtain the foods like wheat, rice, pulses (dal), fruits and vegetables from plants. And the foods like milk, curd, cheese and eggs are obtained from animals. Some people also eat meat, chicken and fish as food.
• These foods are also obtained from animals. Many other animals obtain their food by eating the flesh of other animals. For example, the fish, birds, snakes and insects, all obtain their food from other animals.
• The big fish eats small fish; the birds eat worms and insects; the snake eats frogs and the insects eat dead bodies of animals. The non-green plants also obtain their food from other plants and animals.

• Yeast plant is one such example. Even the plants can eat insects. For example, the pitcher plant and the venus fly-trap are the two plants which eat insects.
• All the animals can be divided into three groups on the basis of their food habits (or eating habits).

These are:

1.  Herbivores,
2. Carnivores, and
3. Omnivores.

We will now discuss herbivores, carnivores and omnivores in somewhat detail. Let us start with the herbivores.

KSEEB Class 10 SSLC Biology Herbivores

Some animals eat only plants (or their products). Those animals which eat only plants are called herbivores. The herbivores may eat grasses, leaves, grains, fruits or the bark of trees. Some of the examples of herbivores are: Goat, Cow, Buffalo, Sheep, Horse, Deer, Camel, Ass, Ox, Elephant, Monkey, Squirrel, Rabbit, Grasshopper and Hippopotamus. Cow is called a herbivore because it eats only plants as food. Thus, herbivores are plant eaters. Herbivores are also called herbivorous animals.

KSEEB Class 10 SSLC Biology Carnivores

Some animals eat only other animals. They do not eat plant food at all. Those animals which eat only other animals as food are called carnivores. Carnivores eat only the meat (or flesh) of other animals. So, we can also say that: Those animals which eat only the meat (or flesh) of other animals are called carnivores. Some of the examples of carnivores are: Lion, Tiger, Frog, Vulture, Kingfisher, Lizard, Wolf, Snake and Hawk. Lion is called a carnivore because it eats only the meat (or flesh) of other animals like deer, rabbit, goat, etc. Thus, carnivores are meat eaters. Carnivores are also called carnivorous animals.

KSEEB Class 10 SSLC Biology Omnivores

• Some animals eat both, plants as well as other animals as food. Those animals which eat both, plants and animals, are called omnivores.
• In other words, the omnivores eat plant food as well as the meat (or flesh) of other animals. Some of the examples of omnivores are: Man (Human beings), Dog, Crow, Sparrow, Bear, Mynah, and Ant.
• Man is called an omnivore because he eats the plant food (such as grains, pulses, fruits and vegetables) as well as the meat of animals (such as goat, chicken and fish).
• Thus, omnivores are plant eaters as well as meat eaters. Omnivores are also called omnivorous animals.

• All the living things on earth actually depend on the sun for their food.
• Plants use the energy of sun and prepare food by photosynthesis. The plants utilise this food for maintaining their life. These plants (and their products) are also eaten up by herbivores and omnivores as food.
• And the carnivores eat herbivores as food. In this way, it is the energy of the sun which provides food for plants, and animals (herbivores, carnivores and omnivores).  the goat is a herbivore which eats plants; man is an omnivore who eats both, plants and meat of goat; and lion is a carnivore which eats the flesh of goat (The man usually does not get eaten up by lion because he is a very clever fellow!).
• An organism either makes its own food from raw materials as green plants do or takes in readymade food as animals do. The process of obtaining food and then using it for obtaining energy, growth and repair of the body, is called nutrition. We will now discuss the animal nutrition in detail.

KSEEB Class 10 SSLC Biology Different Steps In The Process Of Nutrition In Animals

There are five main processes concerned with the use of food by animals. In other words, there are five steps in the process of nutrition in animals. These are: Ingestion, Digestion, Absorption, Assimilation and Egestion. All these steps are discussed below:

Ingestion

In order to provide the energy necessary for growth and carry on life’s activities, we must ‘eat food’ or ‘take food into the body. The process of taking food into the body is called ingestion. In most simple terms, ingestion means ‘eating of food’ by the animal. we put food into our mouth with hands, we are ingesting (the food).

Digestion

• The food of most animals consists of large insoluble molecules which cannot be absorbed by the animal’s body in this form. So, before the food can be used by the animal for various functions like getting energy or for growth, it must be broken down into small, water soluble molecules which can be absorbed by the body.
• The process in which the food containing large, insoluble molecules is broken down into small, water soluble molecules (which can be absorbed by the body) is called digestion. In most simple terms, digestion is the dissolving of the solid food.
• Digestion makes the food soluble so that it can be utilised by the animal’s body. Most animals use both, physical and chemicalmethods for digesting (breaking up) the large food molecules.
• Physical methods include chewing and grinding the food in mouth and chemical methods include the addition of digestive juices(enzymes) to food by the body itself.

Absorption

• Our food contains very big molecules of carbohydrates (like starch), fats and proteins which cannot be absorbed in the body as such.
• They must be broken down into small, water soluble molecules which can be absorbed by the body. This happens in the process of digestion.
• After digestion, the food molecules become small and soluble. The soluble food molecules can pass through the walls of our intestine and go into blood.
• The process in which the digested food passes through the intestinal wall into blood stream is called absorption.

Assimilation

• Blood carries the absorbed food to all the parts of the body. The food then enters each and every cell of the body where it is used for producing energy and for making materials for the growth and repair of the body. The process in which the absorbed food is taken in by body cells and used for energy, growth and repair, is called assimilation.

Egestion

• The whole food which we eat is not digested by our body. A part of the food which we eat remains undigested (or insoluble) which cannot be used by the body.
• This undigested part of the food is then removed from the body in the form of faeces when we go to toilet. The process in which the undigested food is removed from the body is called egestion.

KSEEB Class 10 SSLC Biology Nutrition In Simple Animals

• Amoeba and Paramecium are two very simple animals. The body of each one of them consists of a single cell only. They are called unicellular animals.
• In unicellular animals, all the processes of nutrition are performed by the single cell.
• This point will become more clear from the following example of the nutrition in Amoeba.

Nutrition in Amoeba

Amoeba is a unicellular animal. Amoeba eats tiny (microscopic) plants and animals as food which float in water in which it lives. The mode of nutrition in Amoeba is holozoic. The process of obtaining food by Amoeba is called phagocytosis (Phagocytosis’ means ‘cell feeding). The various steps involved in the nutrition of Amoeba are: ingestion, digestion, absorption, assimilation, and egestion. All the processes of nutrition are performed by the single cell of Amoeba. This is described below.

Ingestion

• Amoeba has no mouth or a fixed place for the ingestion of food (intake of food). Amoeba ingests food by using its pseudopodia.
• When a food particle comes near Amoeba, then Amoeba ingests this food particle by forming temporary finger-like projections called pseudopodia around it.
• The food is engulfed with a little surrounding water to form a food vacuole inside the Amoeba.
• This food vacuole can be considered to be a ‘temporary stomach’ of Amoeba.

Digestion

• In Amoeba, food is digested in the food vacuole by digestive enzymes.
• The enzymes from surrounding cytoplasm enter into the food vacuole and break down the food into small and soluble molecules by chemical reactions.
• Thus, digestion in Amoeba takes place inside the food vacuole due to which the food dissolves (or food becomes soluble).

Absorption

• The digested food present in the food vacuole of Amoeba is absorbed directly into the cytoplasm of Amoeba cell by diffusion.
• Since Amoeba consists of only one small cell, it does not require blood system to carry the digested food.
• The digested food just spreads out from the food vacuole into the whole of Amoeba cell. After absorption of food, the food vacuole disappears.

Assimilation

• A part of the food absorbed in Amoeba cell is used to obtain energy through respiration.
• The remaining part of absorbed food is used to make the parts of Amoeba cell which lead to the growth of Amoeba.
• Thus, on assimilating food Amoeba grows in size. And then Amoeba can reproduce by dividing into two daughter cells.

Egestion

• Amoeba has no fixed place (like anus) for removing the undigested part of food.
• When a considerable amount of undigested food collects inside Amoeba, then its cell membrane suddenly ruptures at any place and the undigested food is thrown out of the body of Amoeba .

•  Paramecium is also a tiny unicellular animal which lives in water. Paramecium uses its hair like structures called cilia to sweep the food particles from water and put them into its mouth.
• The Paramecium has thin, hair-like cilia all over its body. The cilia move back and forth rapidly in water. When the cilia present around the mouth region of Paramecium move back and forth, they sweep the food particles present in water into the mouth of Paramecium.
• This is the first step in the nutrition of Paramecium which is called ingestion. Ingestion is followed by other steps such as digestion, absorption, assimilation and egestion (as explained in the case of Amoeba).

KSEEB Class 10 SSLC Biology Nutrition In Complex Multicellular Animals

• In the complex multicellular animals like man (humans), grasshopper, fish and frog, etc., all the processes involved in nutrition are performed by a combination of digestive organs.
• This combination of digestive organs is called digestive system. We will now describe all the processes in the nutrition of complex multicellular animals by taking the example of nutrition in human beings.
• Please note that a long tube running from mouth to anus of a human being (or other animals) in which digestion and absorption of food takes place is called alimentary canal. Alimentary canal is also called ‘gut’. Let us now study the nutrition in human beings.

KSEEB Class 10 SSLC Biology Nutrition In Human Beings

• The nutrition in human beings (or man) takes place through human digestive system. The human digestive system consists of the alimentary canal and its associated glands.
• The various organs of the human digestive system in sequence are: Mouth, Oesophagus (or Food pipe), Stomach, Small intestine and Large intestine.
• The glands which are associated with the human digestive system and form a part of the human digestive system are: Salivary glands, Liver and Pancreas.
• The human alimentary canal which runs from mouth to anus is about 9 metres long tube. The ducts of various glands open into the alimentary canal and pour the secretions of the digestive juices into the alimentary canal.
• The human digestive system We will now describe the various steps of nutrition in human beings (or man).

Ingestion

• The human beings have a special organ for the ingestion of food. It is called mouth. So, in human beings, food is ingested through the mouth. The food is put into the mouth with the help of hands.

Digestion

• In human beings, the digestion of food begins in the mouth itself. In fact, the digestion of food starts as soon as we put food in as we put food in our mouth. our mouth. This happens as follows:
• The mouth cavity (or buccal cavity) contains teeth, tongue, and salivary glands. The teeth cut the food into small pieces, chew and grind it. So, the teeth help in physical digestion. The salivary glands in our mouth produce saliva.
• Our tongue helps in mixing this saliva with food. Salivais a watery liquid so it wets the food in our mouth. The wetted food can be swallowed more easily. Many times we have observed that when we see or eat a food which we really like, our mouth ‘waters’.
• This watering of mouth is due to the production of saliva by the salivary glands in the mouth. The salivary glands help in chemical digestion by secreting enzymes. The human saliva contains an enzyme called salivary amylase which digests the starch present in food into sugar.
• Thus, the digestion of starch (carbohydrate) begins in the mouth itself. Since the food remains in the mouth only for a short time, so the digestion of food remains incomplete in mouth.

• The slightly digested food in the mouth is swallowed by the tongue and goes down the food pipe called oesophagus.
• The oesophagus carries food to the stomach. This happens as follows: The walls of food pipe have muscles which can contract and expand alternately.
• When the slightly digested food enters the food pipe, the walls of food pipe start contraction and expansion movements.
• The contraction and expansion movement of the walls of food pipe is called peristaltic movement. This peristaltic movement of food pipe (or oesophagus) pushes the slightly digested food into the stomach (In fact, the peristaltic movement moves the food in all the digestive organs throughout the alimentary canal).
• The stomach is a J-shaped organ present on the left side of theabdomen. The food is further digested in the stomach.
• The food is churned in the stomach for about three hours. During this time, the food breaks down into still smaller pieces and forms a semi-solid paste.
• The stomach wall contains three tubular glands in its walls. The glands present in the walls of the stomach secrete gastric juice. The gastric juice contains three substances : hydrochloric acid, the enzyme pepsin and mucus. Due to the presence of hydrochloric acid, the gastric juice is acidic in nature.
• In the acidic medium, the enzyme pepsin begins the digestion of proteins present in food to form smaller molecules. Thus, the protein digestion begins in the stomach.
• Please note that the protein digesting enzyme pepsin is active only in the presence of an acid. So, the function of hydrochloric acid in the stomach is to make the medium of gastric juice acidic so that the enzyme pepsin can digest the proteins properly.
• Another function of hydrochloric acid is that it kills any bacteria which may enter the stomach with food. The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.
• If mucus is not secreted, hydrochloric acid will cause the erosion of inner lining of stomach leading to the formation of ulcers in the stomach. The partially digested food then goes from the stomach into the small intestine.
• The exit of food from stomach is regulated by a ‘sphincter muscle’ which releases it in small amounts into the small intestine.

From the stomach, the partially digested food enters the small intestine.

• The small intestine is thelargest part of the alimentary canal. It is about 6.5 metres long in an adult man. Though the small intestine is very long, it is called small intestine because it is very narrow. The small intestine is arranged in the form of a coil in our belly Please note that the length of the small intestine differs in various animals depending on the type of food they eat.
• For example, cellulose is a carbohydrate food which is digested with difficulty. So, the herbivorous animals like cow which eat grass need a longer ‘small intestine to allow the cellulose present in grass to be digested completely. On the other hand, meat is a food which is easier to digest. So, the carnivorous animals like tigers which eat meat have a shorter ‘small intestine”.

The small intestine in human beings is the site of complete digestion of food (like carbohydrates, proteins and fats). This happens as follows:

•  The small intestine receives the secretions of two glands: liver and pancreas. Liver secretes bile. Bile is a greenish yellow liquid made in the liver which is normally stored in the gall bladder. Bile is alkaline, and contains salts which help to emulsify or break the fats (or lipids) present in the food. Thus, bile performs two functions:

1.  makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it, and
2. bile salts break the fats present in the food into small globules making it easy for the enzymes to act and digest them.

• Pancreas is a large gland which lies parallel to and beneath the stomach  Pancreas secretes pancreatic juice which contains digestive enzymes like pancreatic amylase, trypsin and lipase. The enzyme amylase breaks down the starch, the enzyme trypsin digests the proteins and the enzyme lipase breaks down the emulsified fats.
• The glands in the walls of the stomach secrete gastric juice containing hydrochloric acid, enzyme pepsin and mucus.
•  Liver secretes bile into the small  Pancreas secretes pancreatic intestine. We can also see the gall bladder in juice into the small intestine which contains this picture which stores bile. three digestive enzymes: pancreatic amylase, trypsin and lipase.
• The walls of small intestine contain glands which secrete intestinal juice.
• The intestinal juice contains a number of enzymes which complete the digestion of complex carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol. Glucose, amino acids, fatty acids and glycerol are small, water soluble molecules.
• In this way, the process of digestion converts the large and insoluble food molecules into small, water soluble molecules.
• The chemical digestion of food is brought about by biological catalysts called enzymes.

Absorption

• After digestion, the molecules of food become so small that they can pass through the walls of the small intestine (which contain blood capillaries) and go into our blood.
• This is called absorption. The smallintestine is the main region for the absorption of digested food.

• In fact, the small intestine is especiallyadapted for absorbing the digested food. The inner surface of small intestine has millions of tiny, finger- like projections called villi.
• The presence of villi gives the inner walls of the small intestine a very large surface area. And the large surface area of small intestine helps in the rapid absorption of digested food.
• The digested food which is absorbed through the walls of the small intestine, goes into our blood. The narrow tube in this picture is the small intestine whereas the wider tube is the large intestine.
• Villi are present on the inner surface of small intestine. They help in absorbing digested food into the blood of a person.
• The X-ray photograph of large intestine taken after the person had been given a barium meal.

Assimilation

• The blood carries digested and dissolved food to all the parts of the body where it becomes assimilated as part of the cells.
• This assimilated food is used by the body cells for obtaining energy as well as for growth and repair of the body.
• The energy is released by the oxidation of assimilated food in the cells during respiration.
• The digested food which is not used by our body immediately is stored in the liver in the form of a carbohydrate called “glycogen’.
• This stored glycogen can be used as a source of energy by the body as and when required.

Egestion

• A part of the food which we eat cannot be digested by our body. This undigested food cannot be absorbed in the small intestine.
• So, the undigested food passes from the small intestine into a wider tube called large intestine  (It is called large intestine because it is a quite wide tube).
• The walls undigested part of food becomes almost solid. The last part of the large intestine called ‘rectum’ storesthis undigested food for some time.
• And when we go to the toilet, then this undigested food is passed out(or egested) from our body through anus as faeces or ‘stool’  The act of expelling the faecesis called egestion or defecation. The exit of faeces is controlled by the anal sphincter.

1 mL of very dilute starch solution (1% starch solution) is taken in a test-tube and1 mL of saliva is added to it. After keeping this mixture for half an hour, a few drops of dilute iodine solution are added to the test-tube. There is no change in colour on adding iodine solution. What does thistell you about the action of saliva on starch?

When a mixture of dilute starch solution andsaliva is kept in a test-tube for half an hour, itdoes not produce a blue-black colour with iodine solution showing that no starch is left in the test-tube.

This tells us that the action of saliva has broken down starch into some other substance which does notgive any colour with iodine solution. Actually, saliva contains an enzyme ‘amylase’ which converts starch into a sugar.

KSEEB Class 10 SSLC Biology Dental Caries

• The hard, outer covering of a tooth is called enamel.Tooth enamel is the hardest materialinour body.
• It is harder than even bones. The part of tooth below enamel is called dentine. Dentine is
• The formation of small cavities (or holes) in the teeth due to the action of acid-forming bacteria and improperdental care is called dental caries.

• When we eat sugary food, the bacteria in our mouth act on sugar to produce acids. These acids first dissolve the calcium salts from the tooth enamel and then from dentine forming small cavities (or holes) in the tooth over a period of time.
• The formation of cavities reduces the distance between the outside of the tooth and the pulp cavity which contains nerves and blood vessels.
• The acids produced by bacteria irritate the nerve endings inside the tooth and cause toothache.
• If the cavities caused by dental decay are not cleaned and filled by a dentist, the bacteria will get into the pulp cavity of tooth causing inflammation and infection leading to severe pain.
• If the teeth are not cleaned regularly, they become covered with a sticky, yellowish layer of food particles and bacteria cells called ‘dental plaque’. Since plaque covers the teeth forming a layer over them, the alkaline saliva cannot reach the tooth surface to neutralise the acid formed by bacteria and hence tooth decay sets in.
• Brushing the teeth regularly, after eating food, removes the plaque before bacteria produces acids. This will prevent dental caries or tooth decay. Before we go further and discuss respiration.

KSEEB Class 10 SSLC Biology Respiration

• We have just studied that digested food is assimilated into the body of the living organisms. The assimilated food is used mainly for two purposes :

1. Assimilated food is used as a fuel to get energy for various life processes, and
2. Assimilated food is used as a material for the growth and repair of the body.

• We will now describe how energy is released from the food which is absorbed and assimilated in the cells of the body. Please note that food is the ‘fuel’ for energy production in cells. Let us see how energy is actually obtained.
• Most living things need oxygen (of air) to obtain energy from food. This oxygen reacts with the food molecules (like glucose) present in the body cells and burns them slowly to release energy.
• The energy thus released is stored in ATP molecules in the cells. The body can use this stored energy whenever it wants to do so.
• The process of releasing energy from food is called respiration. When oxygen burns the food in the cells of the body to release energy, then carbon dioxide and water are produced as waste products which are to be eliminated from the body.
• The process of respiration involves taking in oxygen (of air) into the cells, using it for releasing energy by burning food, and then eliminating the waste products (carbon dioxide and water) from the body. The process of respiration can be written in the form of a word equation as follows :
• Food + Oxygen o Carbon dioxide + Water + Energy
• The process of respiration which releases energy takes place inside the cells of the body. So, it is also known as cellular respiration. The process of cellular respiration is common to all the living organisms.
• It provides energy to the cells. There are two by-products of cellular respiration : carbon dioxide and water. Out of these only carbon dioxide is considered the real waste product of respiration because its accumulation in the body is harmful to the organism.
• Water produced during respiration is not harmful to the body. It is rather beneficial for the body.
• Please note that respiration is essential for life because it provides energy for carrying out all the life processes which are necessary to keep the organisms alive.

KSEEB Class 10 SSLC Biology Breathing And Respiration

• The mechanism by which organisms obtain oxygen from the air and release carbon dioxide is calledbreathing. Respiration is a more complex process.
• Respiration includes breathing as well as the oxidation of food in the cells of the organism to release energy.
• Breathing is a physical process whereas respiration also includes biochemical process of oxidation of food.
• The process of breathing involves the lungs of the organism whereas the process of respiration also involves the mitochondria in the cells where food is oxidised to release energy.
• Respiration is actually a biochemical process which occurs in stages and requires many enzymes.
• Themain purpose of respiration is the release of energy from the oxidation of simple food molecules like glucose. The energy released during respiration is used for carrying out the biological functions which are necessary for the maintenance of life and survival of an organism.
• Please note that respiration is just opposite of photosynthesis. This is because photosynthesis makes food (like glucose) by using carbon dioxide, water and sunlight energy, and releasing oxygen; whereas respiration breaks food (like glucose) by using oxygen, and releasing carbon dioxide, water and energy.

KSEEB Class 10 SSLC Biology How Energy Released During Respiration Is Stored

• All the energy released during respiration is not used immediately by an organism (plant or animal). The energy produced during respiration is stored in the form of ATP molecules in the cells of the body and used by the organism as and when required.
• In order to understand this we should first know the meaning of ADP, ATP and inorganic phosphate. These are given below. ADP is a substance called Adenosine Di-Phosphate. The molecules of ADP are present in a cell. ADP has low energy content.
• ATP is a substance called Adenosine Tri-Phosphate. It is also present inside a cell. ATP has a high energy content. Inorganic phosphate is a substance which contains a phosphate group made up of phosphorus and oxygen. Inorganic phosphates are also present in a cell. Inorganic phosphate can be represented by writing just ‘Phosphate’. The inorganic phosphate can also be represented by the symbol Pi (where P stands for phosphate and i for inorganic).
• ADP contains two phosphate groups whereas ATP contains three phosphate groups in its molecule.

The energy released during respiration is used to make ATP molecules from ADP and inorganic phosphate. This happens as follows : ADP combines with inorganic phosphate by absorbing the energy released during respiration to form ATP molecules. That is :

• The energy equivalent to 30.5 kJ/mole is released in this process. The energy released by ATP is used to carry out all the endothermic reactions taking place in the cells.
• Please note that ADP can be converted to ATP by absorbing energy produced during respiration, and ATP can be converted back to ADP releasing energy to be used by the cells, again and again.
• This ensures a continuous supply of energy to the organism. Just as a battery can provide electrical energy for different purposes such as lighting, heating, running radio and computer, etc., in the same way, the energy stored in ATP is used by the body cells for various purposes like contraction of muscles, conduction of nerve impulses, synthesis of proteins, and many other activities related to the functioning of cells. In fact, ATP is known as the energy currency of cells.

KSEEB Class 10 SSLC Biology An Important Discussion

In most of the cases, the organisms (plants and animals) carry out respiration by using oxygen (called aerobic respiration). There are, however, some organisms which carry out respiration without using oxygen (called anaerobic respiration). Before we describe aerobic respiration and anaerobic respiration, we should keep the following points in mind which will help us in understanding the two types of respiration.

1. Glucose is C6H12O6. It is a six carbon atom compound. It is the simple food which is oxidised in the cells of organisms during respiration.

2. The oxidation of glucose to pyruvic acid (or pyruvate) is called glycolysis. It occurs in the cytoplasm of a cell and not in mitochondria. The oxidation of glucose to pyruvic acid does not require oxygen. One molecule of glucose on glycolysis produces two molecules of pyruvic acid (or pyruvate).

3. Pyruvic acid is a three carbon atom compound. It is also called pyruvate. The formula of pyruvic acid or pyruvate is . It is a ketonic carboxylic acid.

4. The fate of pyruvate formed during respiration depends on whether oxygen is present in the cells or not. If oxygen is present in the cells, then pyruvate is completely oxidised to carbon dioxide and water, and a lot of energy is produced (in the form of ATP). If, however, oxygen is not present in the cells (that is, in the absence of oxygen), pyruvate is converted to either ‘ethanol and carbon dioxide’ or ‘lactic acid’ depending on whether such a process is taking place in a plant cell or an animal cell. Much less energy is released in this case.

5. Lactic acid is also a three carbon atom compound. It is also called lactate. The formula of lactic acid or lactate is . It is a hydroxy carboxylic acid.

KSEEB Class 10 SSLC Biology Types of Respiration

So far we have studied that respiration takes place in the presence of oxygen (of air). Respiration can, however, also take place in the absence of oxygen (of air), though it is very rare. This means that oxidation of food to obtain energy can occur in the presence of oxygen as well as in the absence of oxygen. Based on this, we have two types of respiration : aerobic respiration and anaerobic respiration.

KSEEB Class 10 SSLC Biology Aerobic Respiration

• The respiration which uses oxygen is called aerobic respiration. It is called aerobic respiration because it uses air which contains oxygen (‘aerobic’ means ‘with air’).
• In aerobic respiration, the glucose food is completely broken down into carbon dioxide and water by oxidation. Aerobic respiration produces a considerable amount of energy for use by the organism which gets stored in the ATP molecules.
• The breaking down of glucose (food) during aerobic respiration (which is carried out by most of the organisms) can be represented as follows :

• Please note that during aerobic respiration (shown above), 1 molecule of glucose (food) produces 38 energy-rich ATP molecules (Please do not worry about the name ‘Kreb’s cycle’ written in the above equation.
• We will study this in higher classes). All the organisms which obtain energy by aerobic respiration, cannot live without oxygen (of air).
• This is because if there is no oxygen, they cannot get energy from the food which they eat. Mitochondria are the sites of aerobic respiration in the cells .
• Thus, the breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

• The energy released during aerobic respiration is used by the organism. Most of the living organisms carry out aerobic respiration (by using oxygen of air).
• For example, humans (man), dogs,cats, lions, elephants, cows, buffaloes, goat, deer, birds, lizards, snakes, earthworms, frogs, fish, and insects (such as cockroach, grasshopper, houseflies, mosquitoes and ants, etc.) and most of the plants carry out aerobic respiration by using oxygen of air (to obtain energy).

KSEEB Class 10 SSLC Biology Anaerobic Respiration

• The respiration which takes place without oxygen is called anaerobic respiration. It is called anaerobic respiration because it takes place without air which contains oxygen (‘anaerobic’ means ‘without air’).
• The microscopic organisms like yeast and some bacteria obtain energy by anaerobic respiration (which is called fermentation).
• In anaerobic respiration, the micro-organisms like yeast break down glucose (food) into ethanol and carbon dioxide, and release energy.
• This energy is then used by the micro-organisms.
• Anaerobic respiration produces much less energy which gets stored in the ATP molecules. The breaking down of glucose (food) during anaerobic respiration carried out by yeast (plants) can be represented as follows :

• Please note that during anaerobic respiration (shown above), 1 molecule of glucose (food) produces only 2 energy-rich ATP molecules. A few organisms such as yeast plants and certain bacteria (called anaerobic bacteria) can obtain energy from food in the absence of oxygen by the process of anaerobic respiration.
• Please note that all the organisms which obtain energy by anaerobic respiration can live without oxygen (of air).
• For example, the single-celled, non-green plant called ‘yeast’ can live without oxygen because it obtains energy by the process of anaerobic respiration.
• From this discussion we conclude that all the cells do not use oxygen to produce energy. Energy can be produced in cells even without oxygen.
• Please note that the whole process of anaerobic respiration takes place in the cytoplasm of cells.
• We can carry out the fermentation of sugar by using the anaerobic respiration of yeast as follows :
• Take some sugar solution (or fruit juice) in a test-tube and add a little of yeast to it. Close the mouth of the test-tube with a cork and allow it to stand for some time. Now, open the cork and smell.
• A characteristic smell of ethanol (ethyl alcohol) is obtained from the test-tube. A gas is also evolved during this process.
• When this gas is passed through lime-water, the lime-water turns milky showing that it is carbon dioxide gas. This experiment tells us that the products of fermentation of sugar brought about by yeast are ethanol and carbon dioxide.
• We (the human beings) obtain energy by aerobic respiration. But anaerobic respiration can sometimes take place in our muscles (or the muscles of other animals).
• For example, anaerobic respiration takes place in our muscles during vigorous physical exercise when oxygen gets used up faster in the muscle cells than can be supplied by the blood.
• When anaerobic respiration takes place in human muscles (or animal muscles), then glucose (food) is converted into lactic acid with the release of a small amount of energy.
• The breaking down of glucose (food) during anaerobic respiration in muscles can be represented as follows :

• The sudden build up of lactic acid in our muscles during vigorous physical activity can cause muscular ‘cramps’. (The painful contractions of muscles are called cramps). Let us discuss this in a little more detail.
• During heavy physical exercise (or any other heavy physical activity), most of the energy in our muscles in produced by aerobic respiration.
• Anaerobic respiration in muscles provides only some extra energy which is needed under the conditions of heavy physical activity (like running very fast or running for a long time) (see the people running a long distance race).
• The anaerobic respiration by muscles brings about partial breakdown of glucose (food) to form lactic acid. This lactic acid accumulates in the muscles.
• The accumulation of lactic acid in the muscles causes muscle cramps. Thus, muscle cramps occur due to the accumulation of lactic acid in muscles when the muscles respire anaerobically (without oxygen) while doing hard physical exercise.

• We can get relief from cramps in muscles caused by heavy exercise by taking a hot water bath or a massage. Hot water bath (or massage) improves the circulation of blood in the muscles.
• Due to improved blood flow,the supply of oxygen to the muscles increases. Thisoxygen breaks down lactic acid accumulated in muscles into carbon dioxide and water, and hence gives us relief from cramps.
• The anaerobic respiration does not take place only in the muscles of human beings, it also takes place in the muscles of other animals such as lion, tiger, cheetah, deer, and many other animals.

• when they run very fast and require much more energy than normal. This means that even the animals likelion, tiger, cheetah and deer, etc., can get leg cramps due to the accumulation of lactic acid in leg muscles if they run very fast for a considerable time. Please note that :
• the anaerobic respiration in plants (like yeast) produces ethanol and carbon dioxide as end products.
• the anaerobic respiration in animal muscle tissue produces lactic acid as the end product.
• The similarity between aerobic respiration and anaerobic respiration is that in both the cases, energy is produced by the breakdown of food like glucose. The main differences between aerobic respiration and anaerobic respiration are given below.

KSEEB Class 10 SSLC Biology Differences Between Aerobic And Anaerobic Respiration

Aerobic respiration

1. Aerobic respiration takes place in the presence of oxygen.
2. Complete breakdown of food occurs in aerobic respiration.
3. The end products in aerobic respiration are carbon dioxide and water.
4. Aerobic respiration produces a considerable amount of energy.

Anaerobic respiration

1. Anaerobic respiration takes place in the absence of oxygen.
2. Partial breakdown of food occurs in anaerobic respiration.
3. The end products in anaerobic respiration may be  ethanol and carbon dioxide (as in yeast plants), or lactic acid (as in animal muscles).
4.  Much less energy is produced in anaerobic respiration. Let us answer one question now.

Sample Problem. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in :

• cytoplasm
• mitochondria
• chloroplast
• nucleus

Answer. mitochondria

KSEEB Class 10 SSLC Biology Respiration in Plants

Like animals, plants also need energy. The plants get this energy by the process of respiration. Plants also use oxygen of air for respiration and release carbon dioxide. Thus, the respiration in plants also involves the exchange of oxygen and carbon dioxide.So, oxygen and carbon dioxide are called respiratory gases. Therespiration in plants differs from that in animals in three respects :

1. All the parts of a plant (like root, stem and leaves) perform respiration individually. On the other hand, an animal performs respiration as a single unit.

2. During respiration in plants, there is a little transport of respiratory gases from one part of the plant to the other. On the other hand, respiratory gases are usually transported over long distances inside an animal during respiration.

3. The respiration in plants occurs at a slow rate. On the other hand, the respiration in animals occurs at a much faster rate.

KSEEB Class 10 SSLC Biology Plants Get Oxygen By Diffusion

Plants have a branching shape, so they have quite a large surface area in comparison to their volume. Therefore, diffusion alone can supply all the cells of the plants with as much oxygen as they need for respiration. Diffusion occurs in the roots, stems and leaves of plants.

KSEEB Class 10 SSLC Biology Respiration In Roots

• Air is present in-between the particles of soil. The roots of a plant take the oxygen required for respiration from the air present in-between the soil particles by the process of diffusion.
• The extensions of the epidermal cells of a root are called root hair. The root hair are in contact with the air in the soil. Oxygen (from air in the soil particles) diffuses into root hairs and reaches all the other cells of the root for respiration.
• Carbondioxide gas produced in the cells of the root during respiration moves out through the same root hairs by the process of diffusion. Thus, the respiration in roots occurs by the diffusion of respiratory gases (oxygen and carbon dioxide) through the root hairs.
• It has been found that the land plants die if their roots remain waterlogged for a considerable time. This is because too much water expels all the air fromin-between the soil particles.
• Due to this, oxygen is not available to the roots for aerobic respiration. Under these conditions, the roots will respire anaerobically, producing alcohol. This may kill the plant.
• In order to understand the respiration in stems of plants we should remember that the soft stems of small, herbaceous plants have stomata in them whereas the hard and woody stems of large plants and trees have lenticels in them.
• Lenticel is a small area of bark in a woody stem where the cells are loosely packed allowing the gaseous exchange to take place between the air and the living cells of the stem.

KSEEB Class 10 SSLC Biology Respiration In Stems

• The stems of herbaceous plants (or herbs) have stomata. So, the exchange of respiratory gases in the stems of herbaceous plants takes place through stomata.
• The oxygen from air diffuses into the stem of a herbaceous plant through stomata and reaches all the cells for respiration.

• The carbon dioxide gas produced during respiration diffuses out into the air through the same stomata. The hard and woody stems of big plants or trees do not have stomata. In woody stems, the bark (outer covering of stem) has lenticels for gaseous exchange.
• The oxygen from air diffuses into the stem of a woody plant through lenticels and reaches all the inner cells of the stem for respiration.
• The carbon dioxide gas produced in thecells of the stem during respiration diffuses out into the air through the same lenticels.

KSEEB Class 10 SSLC Biology Respiration In Leaves

• The leaves of a plant have tiny pores called stomata.The exchange of respiratory gases in the leaves takes place by the process of diffusion through stomata.
• Oxygen from air diffuses into a leaf through stomata and reaches all the cells where it is used in respiration.
• The carbon dioxide produced during respiration diffuses out from the leaf into the air through the same stomata.
• It should be noted that respiration in leaves occurs during the day time as well as at night. On the other hand, photosynthesis occurs only during the day time (no photosynthesis occurs at night).
• Due to this, the net gaseous exchange in the leaves of a plant is as follows :
•  During day time, when photosynthesis occurs, oxygen is produced. The leaves use some of this oxygen for respiration and the rest of oxygen diffuses out into air. Again, during day time, carbon dioxide produced by respiration is all used up in photosynthesis by leaves. Even more carbon dioxide is taken in from air. Thus, the net gas exchange in leaves during day time is : O2 diffuses out ; CO2 diffuses in.
•  At night time, when no photosynthesis occurs and hence no oxygen is produced, oxygen from air diffuses into leaves to carry out respiration. And carbon dioxide produced by respiration diffuses out into air. So, the net gas exchange in leaves at night is : O2 diffuses in; CO2 diffuses out.

KSEEB Class 10 SSLC Biology Respiration In Animals

Different animals have different modes of respiration. For example :

•  In simple unicellular animals like Amoeba, respiration takes place by the simple diffusion of gases through the cell membrane. Most of the animals have, however, specific organs for respiration.
• The animals like earthworms which live in the soil use their skin to absorb oxygen from air and remove carbon dioxide. So, the respiratory organ in the earthworm is the skin.
• The aquatic animals like fish, prawns and mussels have gills as the respiratory organs which extract oxygen dissolved in water and take away carbon dioxide from the body.
•  In the insects like grasshopper, cockroach, housefly and a mosquito, the tiny holes called spiracles on their body and the air tubes called tracheae are the respiratory organs.

• Grasshopper (an insect) breathes and respires through tiny holes called spiracles, air tubes called tracheae and their branches called tracheoles.
•  The respiratory organs of the land animals such as man (humans), birds, lizard, dog, and frog, etc., are the lungs. (Frogs, however, breathe both by lungs and skin). Once the air (containing oxygen) enters the skin or lungs, blood absorbs the oxygen and transports it to various tissues of the animal. Blood also picks up the carbon dioxide from the tissues and brings it back to the skin or lungs for throwing it out into the air. Please note that all the respiratory organs (whether skin, gills, trachea or lungs) have three common features :

1. All the respiratory organs have a large surface area to get enough oxygen.
2. All the respiratory organs have thin walls for easy diffusion and exchange of respiratory gases.
3. All the respiratory organs like skin, gills and lungs have a rich blood supply for transporting respiratory gases (only in the tracheal system of respiration, air reaches the cells directly).

• The animals which live in water (aquatic animals) use the oxygen dissolved in water to carry out respiration. Since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore, the rate of breathing in aquatic animals in much faster than in terrestrial animals (or land animals).
• A faster rate of breathing provides more oxygen to the aquatic animal. The terrestrial animals (or land animals) use the oxygen of air or atmosphere for breathing and respiration.
• Thus, a terrestrialanimal has an advantage over an aquatic animal in regard to obtaining oxygen for respiration that it is surrounded by an oxygen-rich atmosphere from where it can take any amount of oxygen.
• We will now describe the process of respiration in Amoeba, earthworm, fish and human beings.

KSEEB Class 10 SSLC Biology Respiration In Amoeba

• Amoeba is a single-celled animal. Amoeba depends on simple diffusion of gases for breathing.
• The diffusion of gases takes place through the thin cell membrane of Amoeba. In other words, the exchange of gases in Amoeba takes place through its cell membrane. Let us discuss this in somewhat detail. Amoeba lives in water. This water has oxygen gas dissolved in it. The oxygen from water diffuses into the body of Amoeba through its cell membrane.

• Since the Amoeba is very small in size, so the oxygen spreads quickly into the whole body of Amoeba. This oxygen is used for respiration(energy release) inside the Amoeba cell. The process of respiration produces carbon dioxide gas continuously. This carbon dioxide gas diffuses out through the membrane of Amoeba into the surrounding water.
• Thus, the breathing surface (or respiratory surface) of Amoeba is its cell surface membrane. In addition to Amoeba, other simple animals like Paramecium and Planaria also depend on the simple diffusion of gases for breathing and respiration.Thus, Amoeba, Paramecium and Planaria all breathe through their cell membranes.
• In the small, single-celled animals such as Amoeba, the volume of their body is so small that oxygen can be introduced quickly into the whole body by the process of diffusion.This is because due to the smallness of Amoeba cell, the oxygen does not have to go far. But this is not so in larger animals like earthworms, grasshopper, fish and man (humans), etc.
• In large animals, the volume of body is so big that oxygen cannot diffuse into all the cells of the body quickly. This is because in these cases the oxygen has to travel a very large distance to reach each and every cell of the body. So, in large animals, there is a blood circulatory system to carry oxygen to all the parts of the body quickly (and remove carbon dioxide).
• The blood contains respiratory pigments which take up oxygen from air and carry it to the body cells. This will become more clear from the following example.

Diffusion is insufficient to meet the oxygen requirements of large multicellular organisms like humans because the volume of human body is so big that oxygen cannot diffuse into all the cells of the human body quickly.

• This is because oxygen will have to travel large distances inside the human body to reach each and every cell of the body. Diffusion being a very slow process will take a lot of time to make oxygen available to all the body cells.

• For example, it has been estimated that if diffusion were to provide oxygen in our body, then it would take about 3 years for a molecule of oxygen from our lungs to reach our toes by the process of diffusion. On the other hand, the blood circulatory system in humans carries oxygen to all the parts of the body quickly (and removes carbon dioxide).
• Actually, human blood contains a respiratory pigment called haemoglobin which carries the oxygen from the lungs to all the body cells very efficiently. Haemoglobin is present in red blood corpuscles. We will now discuss the process of breathing and respiration in some large animals like earthworm, fish and humans.

KSEEB Class 10 SSLC Biology Respiration In Earthworm

• The earthworm exchanges the gases through its skin (see Figure 56). This means that the respiratory surface of an earthworm is its skin. The skin of an earthworm is quite thin and moist, and has a good blood supply.

• So, the earthworm absorbs the oxygen needed for respiration through its moist skin. This oxygen is then transported to all the cells of the earthworm by its blood where it is used in respiration. The carbon dioxide produced during respiration is carried back by the blood.
• This carbon dioxide is expelled from the body of the earthworm through its skin. Thus, in earthworm, gaseous exchange takes place through the skin which is thin and moist. Just like earthworms, the leeches also absorb the oxygen needed for respiration through their skin. And carbon dioxide produced inside the leeches (during respiration) also goes out through the skin.

KSEEB Class 10 SSLC Biology Respiration In Fish

• The fish has special organs of breathing called ‘gills’. The fish has gills on both the sides of its head. The gills are covered by gill covers so they are not visible from outside. The fish lives in water and this water contains dissolved oxygen in it. For breathing, the fish uses the oxygen which is dissolved in water. This happens as follows.

• The fish breathes by taking in water through its mouth and sending it over the gills. When water passes over the gills, the gills extract dissolved oxygen from this water. The water then goes out through the gill slits (hidden under the gill cover). Thus, the dissolved oxygen is extracted from water by the fish when it flows over the gills.
• The extracted oxygen is absorbed by the blood and carried to all the parts of the fish. The carbon dioxide produced by respiration is brought back by the blood into the gills for expelling into the surrounding water. The fish has no lungs like us, the gaseous exchange in fish takes place in the gills. So, the respiratory surface of a fish is the surface of its gills.
• It is a common observation that when a fish is taken out from water it dies soon (even though there is a lot of oxygen in the air around it). This is because a fish does not have lungs to utilise the oxygen of air for breathing and respiration. The fish has gills which can extract only dissolved oxygen from water and provide it to fish.
• Gills cannot take in the oxygen from air on land. Since fish does not get oxygen for breathing when taken out of water, it dies. In addition to fish, many other aquatic animals like prawns and mussels also have special organs called ‘gills’ for breathing and respiration.
• Please note that the fish and earthworm do not exchange the gases during respiration in the same way. The fish exchanges the gases by using its special organs called ‘gills’ whereas the earthworm exchanges the gases through its thin and moist ‘skin’.

KSEEB Class 10 SSLC Biology Respiration In Humans

• Like other land animals, human beings are air breathers. Air contains oxygen. The human beings need oxygen to stay alive. We get this oxygen by breathing in air. The oxygen helps to break down the food absorbed in the body to release energy.
• This energy is used for maintaining our life. The process by which energy is released from food in our body is called respiration. Carbon dioxide and water are the two by- products of respiration. The process of respiration takes place inside the cells of our body. It involves our respiratory system.
• The function of respiratory system is to breathe in oxygen for respiration (producing energy from food), and to breathe out carbon dioxide produced by respiration. The breathing organs of human beings are lungs . It is in the lungs that the gases are exchanged between the blood and air.

• The gases exchanged between blood and air are oxygen and carbon dioxide. We will now describe the human respiratory system in detail. Before we go further and describe the human respiratory system in detail, it is necessary to learn the process of breathing which is an important part of respiration. This is discussed below.
• We can live without food and water for many days but we cannot live for more than a few minutes without air. This is because air is necessary for breathing. During breathing, we take air into our lungs through the nose, and then expel it. The ordinary air which we take into the lungs is rich in oxygen but the air expelled from the lungs is rich in carbon dioxide.
• We can now define breathing as follows : Breathing is the process by which air rich in oxygen is taken inside the body of an organism and air rich in carbon dioxide is expelled from the body (with the help of breathing organs). The breathing in human beings takes place through the organs called lungs.
• The taking in of air rich in oxygen into the body during breathing is called ‘inhalation’ and giving out (or expelling) the air rich in carbon dioxide is called ‘exhalation’. Both, inhalation and exhalation take placeregularly during breathing. A breath means ‘one inhalation plus one exhalation’. We know that air contains
• oxygen. So, when we breathe in air, it is actually the oxygen gas present in air which is utilised by our body (to break down food and produce energy). Thus, we ‘breathe in’ air to supply oxygen to the cells of our body (for the breakdown of food to release energy), and we ‘breathe out’ to remove waste product carbon dioxide from our body
• (which is produced during the breakdown of food in the cells). Breathing is a continuous process which goes on all the time throughout our life.

We will now learn the mechanism of breathing.

• That is , we will now learn how air from outside is sucked into our lungs during inhaling (breathing in), and how air from our lungs is pushed out during exhaling (breathing out). The process of breathing takes place in our lungs. Lungs are connected to our nostrils (holes in the nose) through nasal passage (or nasal cavity) and windpipe.
• When we inhale air, it enters our nostrils , passes through nasal passage and windpipe, and reaches our lungs. Our two lungs hang in an airtight space in our body called ‘chest cavity’. Around the sides of the chest cavity is the rib cage with sheets of muscles between the ribs. The rib cage encloses the lungs in it .
• At the bottom of the chest cavity is a curved sheet of muscle called diaphragm .Diaphragmforms the floor of chest cavity. Breathing involves the movements of the rib cage and the diaphragm. This happens as follows :

Breathing in. When we breathe in (or inhale), then two things happen at the same time :

• the muscles between the ribs contract causing the rib cage to move upward and outward, and
•  the diaphragm contracts and moves downward [see Figure 63(a)]. The upward and outward movement of rib cage, as well as the downward movement of diaphragm, both increase the space in the chest cavity and make it larger. As the chest cavity becomes larger, air is sucked in from outside into the lungs. The lungs get filled up with air and expand.

• Breathing in : chest cavity becomes (b) Breathing out : chest cavity becomes bigger, air is sucked into lungs smaller, air is pushed out of lungs . The mechanism of breathing.
•  Breathing out. When we breathe out (or exhale), even then two things happen at the same time :
• the muscles between the ribs relax causing the rib cage to move downward and inward, and
• thediaphragm relaxes and moves upward. The downward and inward movement of rib cage,as well as the upward movement of diaphragm, both decrease the space in our chest cavity and make it smaller. As the chest cavity becomes smaller, air is pushed out from the lungs.

KSEEB Class 10 SSLC Biology Respiratory System in Humans

• In human beings, many organs take part in the process of respiration. We call them organs of respiratory system. The main organs of human respiratory system are : Nose, Nasal passage (or Nasal cavity), Trachea, Bronchi, Lungs and Diaphragm. The human respiratory system.
• The human respiratory system begins from the nose. Our nose has two holes in it which are called nostrils. There is a passage in the nose behind the nostrils which is called nasal passage (or nasal cavity). The air for respiration is drawn into our body through the nostrils present in the nose.

• This air then goes into nasal passage. The nasal passage is separated from the mouth cavity (buccal cavity or oral cavity) by a hard, bony palate so that we can breathe in air even when we are eating food (and the mouth cavity is filled with food). The nasal passage is lined with fine hair and mucus (Mucus is secreted by the glands inside the nasal passage).
• When air passes through the nasal passage, the dust particles and other impurities present in it are trapped by nasal hair and mucus so that clean air goes into the lungs. The part of throat between the mouth and wind pipe is called pharynx. From the nasal passage, air enters into pharynx and then goes into the wind pipe (or trachea) .
• The trachea is a tube which is commonly known as wind pipe. The air coming from the nostrils during breathing passes through trachea. Trachea does not collapse even when there is no air in it because it is supported by rings of soft bones called cartilage. The upper end of trachea has a voice box called larynx.
• The trachea runs down the neck and divides into two smaller tubes called ‘bronchi’ at its lower end. (The singular of bronchi is bronchus). The two bronchi are connected to the two lungs. The lungs lie in the chest cavity or thoracic cavity which is separated from abdominal cavity by a muscular partition called diaphragm.
• The lungs are covered by two thin membranes called pleura. The lungs are enclosed in a ‘rib cage’ made of bones called ‘ribs’. We have not shown the rib cage to keep the diagram simple. Each bronchus divides in the lungs to form a large number of still smaller tubes called ‘bronchioles’.
• The smallest bronchioles have tiny air-sacs at their ends. The pouch-like air-sacs at the ends of the smallest bronchioles are called ‘alveoli’ (singular alveolus). The walls of alveoli are very thin and they are surrounded by very thin blood capillaries. It is in the alveoli that oxygen is taken into the body and carbon dioxide is eliminated. In other words, it is in the alveoli that gaseous exchange takes place.
• The human lungs have been designed to maximise the exchange of gases as follows : There are millions of alveoli in the lungs. The presence of millions of alveoli in the lungs provides a very large area for the exchange of gases. And the availability of large surface area maximises the exchange of gases.
• For example, if all alveoli from the two human lungs are unfolded, they would give an area of about 80 square metres (which is nearly the size of a tennis court !). The diaphragm is a sheet of muscle below the lungs. It helps in ‘breathing in’ and ‘breathing out’. The muscles of chest also help in breathing in and breathing out.

• When we breathe in air, the diaphragm and muscles attached to the ribs contract due to which our chest cavity expands. This expansion movement of the chest increases the volume inside the chest cavity.
• Due to increase in volume, the air pressure decreases inside the chest cavity and air from outside (being at higher pressure) rushes into the lungs through the nostrils, trachea and bronchi. In this way, during the process of ‘breathing in’ the air sacs or alveoli of the lungs get filled with air containing oxygen.
• The alveoli are surrounded by very thin blood vessels called capillaries carrying blood in them. So, the oxygen of air diffuses out from the alveoli walls into the blood. The oxygen is carried by blood to all the parts of the body (This oxygen is carried by a red pigment called haemoglobin present in blood).
• As the blood passes through the tissues of the body, the oxygen present in it diffuses into the cells (due to its higher concentration in the blood). This oxygen combines with the digested food (glucose) present in the cells to release energy. Carbon dioxide gas is produced as a waste product during respiration in the cells of the body tissues. This carbon dioxide diffuses into the blood (due to its higher concentration in body tissues).
• Blood carries the carbon dioxide back to the lungs where it diffuses into the alveoli. When we breathe out air, the diaphragm and the muscles attached to the ribs relax due to which our chest cavity contracts and becomes smaller. This contraction movement of the chest pushes out carbon dioxide from the alveoli of the lungs into the trachea, nostrils and then out of the body into air.
• In this way the process of gaseous exchange is completed in the human respiratory system. Please note that during the breathing cycle, when air is taken in (or inhaled) and let out (or exhaled), the lungs always contain a certain residual volume of air so that there is sufficient time ‘for the oxygen to be absorbed’ into the blood and ‘for the carbon dioxide to be released’ from the blood. Another point to be noted is that carbon dioxide is more soluble in water (than oxygen), so it is mostly transported in the dissolved form in our blood.

Experiment to Show That Carbon Dioxide is Produced During Respiration

• We know that carbon dioxide gas turns lime-water milky. The fact that carbon dioxide is produced during respiration can be shown by demonstrating the effect of inhaled air and exhaled air on lime-water.
• The apparatus to demonstrate the effect of inhaled air and exhaled air on lime-water.
• The apparatus consists of two boiling tubes A and B fitted with two-holed corks. The boiling tubes A and B are connected through a special type of glass tube C. The left arm of glass tube C is short which goes in the boiling tube A. The right arm of glass tube C is long and dips in lime-water in boiling tube B.The boiling tube A has another bent glass tube D whose longer side dips in lime-water contained in it.
• The boiling tube B has also another short, bent tube E in it which does not dip in lime-water.  To perform the experiment, we put the top end of the tube C in mouth and ‘breathe in’ and ‘breathe out’ gently. When we breathe in, then the inhaled air (fresh air) enters the glass tube D and passes through the lime-water in boiling tube A. And when we breathe out, then the exhaled air (coming from our lungs) passes through the lime-water in boiling tube B.

• We continue to breathe in and breathe out for about five minutes. We will find that the lime- water in boiling tube A (in which inhaled air is passed) turns milky only slightly but the lime-water in boiling tube B (in which exhaled air is passed) turns milky appreciably. This shows that less carbon dioxide is present in inhaled air but much more carbon dioxide is present in exhaled air.
• From this observation we conclude that carbon dioxide is produced during respiration (which comes out in exhaled air). The air which we ‘inhale’ is a mixture of gases and the air which we ‘exhale’ is also a mixture of gases.
• The only difference in the inhaled air and exhaled air is that they contain different proportions of oxygen, carbon dioxide and water vapour. (The proportion of nitrogen gas in the inhaled air and exhaled air remains the same, 78 per cent, because it is neither used up in respiration nor produced during respiration). The proportions of oxygen, carbon dioxide and water vapour in ‘inhaled air’ and ‘exhaled air’ are given below :

• We can see from the above figures that the air which we inhale contains a greater proportion (21 per cent) of oxygen. Now, some of the oxygen of inhaled air is used up in breaking down glucose food during respiration, so the exhaled air which comes out after the process of respiration contains a lower proportion (16.4 per cent) of oxygen.
• The air which we inhale contains a lower proportion (0.04 per cent) of carbon dioxide. Now, during respiration, when oxygen breaks down glucose food, then a lot of carbon dioxide is produced, so the exhaled air which comes out after respiration contains a much higher proportion (4.4 per cent) of carbon dioxide.
• Again, the air which we inhale contains only a little of water vapour. Now, when glucose food is broken down by oxygen during respiration, then water is also produced (alongwith carbon dioxide). So, the exhaled air contains a lot more water vapour than inhaled air.

KSEEB Class 10 SSLC Biology Rate of Breathing

• The process of breathing pumps in oxygen into our body (and removes carbon dioxide). Breathing occurs involuntarily (on its own) but the rate of breathing is controlled by the respiratory system of brain.
• The average breathing rate in an adult man at rest is about 15 to 18 times per minute. This breathing rate increases with increased physical activity. For example, if we do some physical exercise (like sit-up exercise), then our breathing rate goes up considerably. This is because when we do some physical exercise, then our body needs more energy.
• And to produce more energy through respiration, our body requires more oxygen gas. Rapid breathing supplies more oxygen to body cells for producing more energy required for doing physical exercise. Thus, we breathe faster after exercise so as to produce more energy to compensate the loss of energy suffered by our body in doing exercise.
• We all breathe through nose. We can, however, not breathe inside water when we are diving. This is because water does not have free air or oxygen for us to breathe (and we do not have gills like the fish to utilise oxygen dissolved in water). So, the deep sea divers carry oxygen gas cylinders with them for breathing when they go under the sea.
• We have just studied that oxygen required for breathing and respiration (release of energy) is carried by haemoglobin present in our blood. The normal range of haemoglobin in the blood of a healthy adult person is from 12 to 18 grams per decilitre (12 to 18 g/dL) of blood. The deficiency of haemoglobin in the blood of a person reduces the oxygen-carrying capacity of blood resulting in breathing problems, tiredness and lack of energy.
• The person looks pale and loses weight. Many times we have heard of carbon monoxide poisoning. This happens as follows. Carbon monoxide gas (CO) is formed whenever a fuel burns in an insufficient supply of air. For example, if coal (or charcoal) is burned in a closed space (like a room with closed doors and windows), then a lot of carbon monoxide is formed.
• Carbon monoxide is also produced when petrol burns in a car engine. Now, we know that haemoglobin present in our blood carries oxygen to all the parts of our body.

• Haemoglobin has more affinity (or attraction) for carbon monoxide than oxygen, So, if carbon monoxide gas is inhaled by a person, then this carbon monoxide binds very strongly with haemoglobin in the blood and prevents it from carrying oxygen to the brain and other parts of the body.
• Due to lack of oxygen, the person cannot breathe properly. If carbon monoxide is inhaled for a long time, then the person becomes unconscious and can even die due to oxygen starvation.
• The persons having breathing problems (or respiratory problems) are given oxygen masks to facilitate breathing. In serious cases, the patient is put on a machine called ‘ventilator’ in which a tube is inserted directly into the trachea (or wind pipe) of the patient to help him in breathing comfortably. Before we go further and describe the transport of materials in plants and animals.

KSEEB SSLC Class 10 Social Science Notes History

• Chapter 1 Advent of Europeans to India Notes
• Chapter 2 The Extension of the British Rule Notes
• Chapter 3 The Impact of British Rule in India Notes
• Chapter 4 Opposition to British Rule in Karnataka Notes
• Chapter 5 Social and Religious Reformation Movements Notes
• Chapter 6 The First War of Indian Independence (1857) Notes
• Chapter 7 Freedom Movement Notes
• Chapter 8 Era of Gandhi and National Movement Notes
• Chapter 9 Post Independent India Notes
• Chapter 10 The Political Developments of 20th Century Notes

KSEEB SSLC Class 10 Social Science Notes Political Science

• Chapter 1 The Problems of India and their Notes
• Chapter 2 Indian Foreign Policy Notes
• Chapter 3 India’s Relationship with Other Countries Notes
• Chapter 4 Global Problems and India’s Role Notes
• Chapter 5 International Institutions Notes

KSEEB SSLC Class 10 Social Science Notes Sociology

• Chapter 1 Social Stratification Notes
• Chapter 2 Labour Notes
• Chapter 3 Social Movements Notes
• Chapter 4 Social Problems Notes

KSEEB SSLC Class 10 Social Science Notes Geography

• Chapter 1 Indian Position and Extension Notes
• Chapter 2 Indian Physiography Notes
• Chapter 3 Indian Climate Notes
• Chapter 4 Indian Soils Notes
• Chapter 5 Indian Forest Resources Notes
• Chapter 6 Indian Water Resources Notes
• Chapter 7 Indian Land Resources Notes
• Chapter 8 Indian Mineral & Power Resources Notes
• Chapter 9 Indian Transport and Communication Notes
• Chapter 10 Indian Industries Notes
• Chapter 11 Indian Natural Disasters Notes
• Chapter 12 Indian Population Notes

KSEEB SSLC Class 10 Social Science Notes Economics

• Chapter 1 Development Notes
• Chapter 2 Rural Development Notes
• Chapter 3 Money and Credit Notes
• Chapter 4 Public Finance and Budget Notes

KSEEB SSLC Class 10 Social Science Notes Business Studies

• Chapter 1 Bank Transactions Notes
• Chapter 2 Entrepreneurship Notes
• Chapter 3 Globalization of Business Notes
• Chapter 4 Consumer Education and Protection Notes