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Two ways in which biodegradable substances would affect the environment are:
(i) Decomposition of biodegradable wastes produces foul smell which spreads in the environment and makes the life of people miserable.
(ii) Flies breed at huge heaps of biodegradable wastes carrying the germs and spread diseases such as typhoid, diarrhoea, tuberculosis, cholera, etc.

An aerosol can be defined as a dispersion of solid and liquid particles suspended in gas. Atmospheric aerosols, unsurprisingly, refer to solid and liquid particles suspended in air. Aerosols are produced by dozens of different processes that occur on land and water surfaces, and in the atmosphere itself. There is a demand to put a ban on them because of their deteriorating effect on Earth,s ozone layer

1. Leaves of the plants decay and reduces soil fertility,

2. Bio-degradable substances have carbon. When this is burnt, CO₂ and CO are produced and causes air pollution.

Wastes generated in our house daily are as follows 

(a) Kitchen wastes 

(b) Paper wastes like newspapers, bags, envelopes 

(c) Plastic bags 

(d) Vegetable/fruit peels/rind Measures for disposal 

Measures to take to dispose house waste are 

(a) Segregation of biodegradable and non-biodegradable wastes. 

(b) Safe disposal of plastic bags. 

(c) Vegetable/fruit peels can be placed near trees/plants, which on decomposition will enrich the soil with nutrients. 

(d) Give paper wastes for recycling.

(e) Prepare a compost pit for kitchen wastes.

Polythene bags and plastic containers.

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

Example – Green plants and certain blue-green algae  

2. Those organisms which consume food (eat food) prepared by producers are called  consumers. 

Example – Lion and Tiger.

(i) They produce foul smell during decomposition process.

(ii) They may produce harmful gases such as ammonia, methane and carbon dioxide. 

The Great Himalayan National park contains within its reserved area, alpine meadows which were grazed by sheep in summer. But now without regular grazing by sheep, the grass first grows very tall and then falls over, preventing fresh growth.

(a) Trophic Level

(b) Abiotic components

(c) Consumers

(d) Environment

(e) Ecosystem

Answer is (B) 4

Bio-magnification.

Non-degradable chemicals accumulates progressively at each trophic level. Since the man is at the apex of all the food chains, the concentration of harmful chemicals may be more in human beings.

Producers – Plants, Green Algae 

Consumers – All Animals.

Grass → Insects → Frog → Snake. 

Producers – Grass. Primary Consumers – Insects. 

Secondary Consumers – Frog 

Tertiary consumers – Snake. 

Aquatic Plants → Insects → Fish → Crane. 

Producers – Aquatic Plant. 

Primary Consumers – Insects 

Secondary Consumers – Fish 

Tertiary consumers – Crane

1. If decomposers are removed from the food web then the biological cycles are not completed. 

2. If the decomposers are not present in an ecosystem the remains of the other organisms accumulate.

Farmers use various fertilizers and pesticides (chemicals) to protect their crops and plants from diseases. These chemicals are absorbed by the plants along with water and minerals from the soil and are taken by aquatic plants and animals as well. 

And since these chemicals are non-biodegradable, they will remain in the food chain. Humans are the final consumers of every food chain hence, all of this chemical gets in their body when they feed on organisms or plants of the lower trophic level. In this way, these fertilizers can cause harm to us.

i) Plants, Grass, Trees Phytoplanktons etc. 

ii) Grass → Rabbit → Fox → Tiger 

iii) Tiger, Vulture, Crane, Owl, Peacock etc. 

(OR) 

The animals which are at 4th trophic level in a food chain are called as Tertiary Consumers. 

iv) Rabbit, Deer, Goat, Cow

A food web indicates that the number of possible links for food in an ecosystem and reflects the fact that the whole community is a complex inter-connected unit.

Food chain is a simple representation of energy flow in nature. 

For example: A rat eats grains a snake eats a rat, which in turn, is eaten by an eagle. In a food chain, the number of trophic levels are limited to 4 - 5. This is because according to 10% law of energy transfer, only 10% of energy passes from one trophic level to next. Thus the amount of energy decreases with successive trophic levels. Alter five trophic levels, existence of organisms would become impossible with such negligible amount of energy.

The food chain in which the transfer of food energy occurs through a series of parasites at each tropic level is called parasitic food chain. 

Ex: Tree →birds → lice → protozoans.

Ants, termites, earth worms are called as detrivores because they feed on detritus.

Bacteria and fungi

CO₂ and Water

I support her for the following reason. 

1. A snake eating a mouse in a field or lawn occupies the third tropic level.

Plant → Mouse → Snake 

2. When the snake eats a frog in the same field, it occupies the fourth tropic level in a food chain. It is because the frog feed on some of the insects that depend on the plants. 

Plant → Insect → Frog → Snake 

3. Thus, a given species may occupy more than one tropic level in the same ecosystem at the same time. 

4. This is to satisfy its food needs, as it cannot do so by occupying one tropic level.

Zebra, goat, horses and sheep are all those organisms which eat producers (green plants) for energy and hence are herbivores. They all cannot make food by themselves hence; they feed on plants which can make food for themselves.

1. Forming eco-clubs: These clubs consists of student representatives from each class. They will take up the eco-friendly activities and encourage the people of that village to follow environment friendly activities. 

2. Setting up garden at school: This ensures the school and its premises green through planting of flowering plants, vegetables and fruit trees. It is a symbol of biodiversity because various plants and animals inhabit the garden. 

3. Electricity conservation programme: To save energy the school implements certain hours to be switched off habit. This switching off programme for one hour from 3.30 p.m. to 4.30 p.m. help conserve electricity in every classroom. 

4. Pollution prevention programme: A ‘no burning of trash policy should be implemented in the school. Waste materials are recycled and properly disposed to ensure a clean, waste-free environment. 

5. Making compost by organic wastes: By digging a pit at one corner of the school and throwing the organic waste particularly of mid day meal waste into pit and covering with soil layers prepares compost which can be used as manure for plants. This creates a clean environment in the school. 

6. Using cloth bags instead of polythene bags by pupil. 

7. Collection of solid waste materials and proper management of its helps in reducing soil pollution. 

8. Children should be encouraged to follow ‘3R’ system i.e. Reduce, Re use and Recycle different substances.

(1) Forming eco clubs: These clubs consists of student representatives from each class. They will take up the ecofriendly activities and encourage the people of the village to follow environment friendly activities.

(2). Setting up garden at school: This ensures the school and its premises green through planting of flowering plants, vegetables and fruit trees. it is a symbol of biodiversity because various plants and animals inhabit the garden.

Electricity conservation programme: To save energy the school implements certain hours to be switched offf habit. this switching off prigramme for one hour from 3.30 p.m. to 4.30 om help conserve electricity in every classroom.

Ecosystem is the functional unit of the environment comprising of the living and non-living components.

Ecosystem is the functional unit of the environment comprising of the living and non-living components.

1. Sparrows are useful to control harmful insects like locust which damage food grains. 

2. Chemical pesticides are the cause for destruction of sparrows and useful insects. 

3. By using biological methods we can conserve the sparrow population.

There are the decreasing number of insects and worms due to the use of chemical pesticides. This has resulted in a decrease in the number of sparrows as sparrows used to eat insects and worm. These birds are responsible for the pollination of flowers. The birds of this group are considered to the vulnerable and endangered group. So, it is necessary to take measures in order to protect and increase the number of these birds. There are gardens and parks developed which can be used for the birds for living. The Wildlife Act also proposed certain rules to protect these birds. The amount of radiations should be decreased which will protect the birds. 

C) Cellulose, lignin

(B) Trophic levels

A) Both a & b are true

(C) Human being

Niche denotes the mode of life of an organism in the food web.

Niche denotes the animal’s position and its food.

Correct option is B) Food

D) All of the above

According to 10% Law, only 10% of energy is transferred from one trophic level to next trophic level. Plants are producers so if man will be vegetarian then he will directly eat plant based foods so will get maximum energy but if he will be nonvegetarian he will eat herbivores like goat, hen that feeds upon plants so man will be at higher trophic level and will get minimum energy as compared to being vegetarian. So accordingly in a food chain man can place himself in an advantageous position. For example- animals which are herbivores get 10% of energy from plants suppose 100 J according to 10% rule. When man will feed upon these animals they get only 10 J which is 10% of 100 J. But if man will feed directly on plants get 100 J hence vegetarians are at an advantageous position and get more energy than non-vegetarians.

Enzymes are specific in their action. Specific enzymes are needed for the breakdown of a particular substance. 

So, enzymes which digest carbohydrates in food are specific for acting only on the carbohydrates and hence cannot act on other substances like coal.

Being a vegetarian will increase the amount of energy taken up by your body. As we know that energy decreases ate each successive trophic level. It is least available for the last trophic level. Humans are the final (tertiary) consumers of any food chain; hence if they skip the primary and secondary consumers and directly feed on plants, then they can have the more amount of energy comparative to the energy if they don’t skip.

We know that, vegetarians obtain food directly from plants while non- vegetarians get the food from animals. Animals (herbivores) contain 10% of food energy as compared to plants (producers). For example; the same amount of producer which supplies sav 1000J of food energy to a vegetarian will provide only 100 J of food energy to a non vegetarian. Hence, a vegetarian will be at an advantageous position.

Plants are called producers because green plants prepare their own food from simple  inorganic substances like carbon dioxide and water by using sunlight energy in the presence of  chlorophyll.

(i) (a) Environmental pollution.
(b) Burning plastics can cause pollution.
(c) Plastic cause harm to the cattle/animals if enter inside their alimentary canal.
(ii) Paper bags/jute bags can be used instead of plastic bags. (Any other relevant view of the student)

Advantage of Ozone–When it is in the stratosphere it does not allow the ultraviolet radiations to reach the earth, as UV radiations cause skin cancer and cataract. Disadvantage of ozone: On ground level ozone is poisonous gas.

Aquarium is not a terrestial ecosystem.

Characteristics of a food chain:
(i) Unidirectional
(ii) Helps in understanding the food relationship and interaction among various organisms in an ecosystem
(iii) Helps to understand movement of toxic substances and the problem of their biological magnification
Moral values possessed by Dharmesh:
(i) Sensitive towards environment
(ii) Possesses knowledge about biological magnification
(iii) Scientific temperament
(iv) Conscious (Any three)

All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem. For example a garden is an ecosystem which consists of plants, insects, water, soil etc.

(a) The two components of the ecosystem are: Biotic and Abiotic.

Biotic components comprises of all the living organisms like humans, animals, plants etc and Abiotic component comprises of the nonliving things like air, mineral soil, water and sunlight.

(b) Ponds and lakes are an example of natural ecosystem whereas the aquarium is an example of artificial ecosystem. Ponds do not need to be cleaned because it has microorganisms, like bacteria and fungi that break-down the dead remains and waste products of organisms and clean the pond naturally. The aquarium does not contain soil or decomposing bacteria or fungi which helps in degrading complex organic substance into simple inorganic substance, so it needs to be cleaned from time to time.

(i) A food chain is always straight and proceeds in a progressive straight line.
(ii) A food chain helps in understanding the food relationship and interactions among various organisms in an ecosystem.
(iii) It also helps to understand the movement of toxic substances in an ecosystem and the problem of their biological magnification.