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A food chain always represents a unidirectional flow of energy from one trophic level to another. As a food chain proceeds from autotrophs to heterotrophs to decomposers energy gets transferred. The flow of energy in an ecosystem starts with sunlight (the ultimate source of all energy on Earth) which is absorbed by the producers, goes to the consumers, then to the decomposers, and back to the producers to start all over again.

Grass land Ecosystem: Grass → grasshopper → frog → snake → peacock. 

Pond Ecosystem : Blue-green algae → small fish → big fish → birds

The accumulation of chemicals in the bodies of the organism that belongs to the top most tropic level is called biological magnification. As human beings occupy highest trophic level its maximum concentration was found in human beings only, which resulted in neurological disorders due to damaging of CNS (Central Nervous System).

Food chain is defined as the phenomenon of transfer of energy through series of organisms falling on successive trophic levels. 

Example: sun is the ultimate source of energy. Producers or green plants photosynthesize and utilize solar energy. Thereafter the energy is transferred to other successive levels. 

Food chain can be depicted as follows: 

Plants → grasshopper → frog → snake → decomposers 

Bacteria and fungi are called decomposers as they break down the dead remains and waste of organisms. They convert the organic complex substance into simple inorganic substances that go into the soil and are used up by plants. 

Two advantages of decomposers: 

1. They return the components back to nature and creates balance in the environment. 

2. They act as cleansing agents of the atmosphere.

Plastic is an example non-biodegradable substance.

Plants is an example biodegradable substance.

The three environmental problems caused by human are:

1) Human activity like the building of industry, like sugar mill, chemical industry, emitted certain harmful effluent that pollutes air and water and soil as well. Improper waste management leads to persistence of non-biodegradable products in the environment which causes health issues to animals and plants. 

2) Deforestation- cutting of trees led to the migration of certain animals and cause the extinction of the species. It also results in floods and droughts. The primitive agricultural practice caused soil erosion. 

3) The burning of fossil fuels leads to the depletion of ozone layer and may cause several health problems.

(a) Environmental pollution is an undesirable change in the physical, chemical or biological characteristics of the natural environment, brought about by man’s activities. This pollution may affect the soil, rivers, seas or the atmosphere.

(b)

(c) Biodegradable pollutants are sewage and agricultural waste.

Correct option (C) Sustainable development does not consider the view points of stakeholders. 

Explanation:

Sustainable development considers the view point of stakeholders by management of available resources and development of new techniques to meet the changing human needs, at the same time maintaining and improving the quality of environment and conserving natural resources.

Correct option  (B)

Explanation:

The given figure shows food web in an aquatic ecosystem. A pyramid of biomass is the graphic representation of biomass (total amount of living or organic matter in an ecosystem at any time) per unit area in different trophic levels. lt is inverted in an aquatic ecosystem where the biomass of a trophic level depends upon reproductive potential and longevity of its members. Therefore, the biomass of organisms gradually increases at successive trophic levels from producers (aquatic plants) to top carnivores (large fish).

(C) Greater reduction in the number of hawks than in the number of caterpillars

DDT, Aldrin, Malathian, Altrazine, Monocrotophos, Endosulphan etc.

When green plants are eaten by herbivores, a great deal of energy is lost in the form of heat to the environment 

Some amount goes into digestion and in doing work and the rest goes towards growth and reproduction.

The remaining is only an average of 10% of the food eaten that is turned into its own body and made available for the next level of consumers.

The advantages of using disposable paper cups over disposable plastic cups are: 

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 be disposed off by burning without causing much air pollution. On the other hand, burning of plastic cups produces toxic gases (poisonous gases) which causes too much air pollution.

LEAVE PLASTIC BEHIND 

Stay away from those evil plastic bags! The best you can do is bringing your snacks in reusable bags or containers. 

THROW EVERYTHING AWAY 

Bring your own bags with you, this will ensure you throw everything away! Trash doesn’t just disappear and we all know it, so take everything you brought back with you and that will make the ocean smile. 

IF YOU SPOT TRASH 

Pick up everything you spot on the beach, but picking up a couple of leftovers will do good to keep the beach clean. 

MAKE SMALL CHANGES 

Details matter a lot here, for example you could bring a reusable water bottle to your beach day instead of disposable water bottles!. 

CAREFUL WITH THAT BONFIRE 

Don’t you just love roasting some marshmallows on a cozy beach night? We do too! However, try not to burn your debris on the bonfire, it’ll go straight to the sand and into the ocean once time goes by. Don’t forget to put your fire out properly too. 

TAKE CARE OF PETS 

If you’ve brought your puppy to the beach, that’s great, nothing beats a puppy trying to swim! However, remember to pick up their poops.

Spread of all these non-biodegradable wastes on the beach will go in the oceans with the waves. This will cause ocean pollution or marine pollution. This will lead severe consequences like: 

1. Effect of Toxic Wastes on Marine Animals 

Oil spill is dangerous to marine life in several ways. The oil spilled in the ocean could get on to the gills and feathers of marine animals, which makes it difficult for them to move or fly properly or feed their children. The long term effect on marine life can include cancer, failure in the reproductive system, behavioral changes, and even death. 

2. Disruption to the Cycle of Coral Reefs 

Oil spill floats on the surface of water and prevents sunlight from reaching to marine plants and affects in the process of photosynthesis. Skin irritation, eye irritation, lung and liver problems can impact marine life over long period of time.

3. Depletes Oxygen Content in Water 

Most of the debris in the ocean does not decompose and remain in the ocean for years. It uses oxygen as it degrades. As a result of this, oxygen levels go down. When oxygen levels go down, the chances of survival of marine animals like whales, turtles, sharks, dolphins, penguins for long time also go down.

4. Effect on Food Chain 

Chemicals used in industries and agriculture get washed into the rivers and from there are carried into the oceans. These chemicals do not get dissolved and sink at the bottom of the ocean. Small animals ingest these chemicals and are later eaten by large animals, which then affect the whole food chain.

5. Affects Human Health 

Animals from impacted food chain are then eaten by humans which affects their health as toxins from these contaminated animals gets deposited in the tissues of people and can lead to cancer, birth defects or long term health problems.

B) Bio – magnification

Ozone layer is getting depleted at the higher levels of the atmosphere due to effect of chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers.

1. c. Both biodegradable and nonbiodegradable waste.

2. a. Plastic bags

3. b. Because it creates contamination

4. c. Use them to store water at home

5. a. Make compost from them.

a. Ayush with his friends can form a team of volunteers to keep the beach clean. He can conduct cleanliness drive, can prepare banners to request tourists to keep beach clean. He can keep dustbins at different places on beach and request tourists to throw wastes into dustbins.

b. Government can enforce laws to prevent people throwing waste items on the beach otherwise some punishment would be there. Dustbins should be kept at proper distances on beach and people should be encouraged to throw wastes into dustbins.

CFCs deplete ozone from ozone shield, resulting in increasing the passage of harmful ultraviolet radiation to the earth.

If we kill all the organisms in one trophic level, the following effects will take place: 

• The population of organisms in previous trophi’c level will increase. 
• The organisms in next trophic level will not be able to get the food, so they will migrate to some other ecosystem or die. 
• It will cause an ecological imbalance in the food chain

 Trophic level is the position that an organism occupies in a food chain, where transfer of food or energy takes place.

1. d. Ozone is harmless to breathe

2. a. Traps heat

3. a. Skin cancers

4. b. The eggs did not hatch

5. c. Estimating the quantity of organic matter in sewage water

• Yes, the impact of removing all the organisms in a trophic level will be different for different trophic levels.

• Removing producers will affect herbivores heavily due to absence of food. They will die. 

• Similarly, the carnivores would also die in absence of herbivores. 

• Removing herbivores from the food chain, Producers would grow enormous; carnivores would not get food. 

• Removing carnivores, the population of herbivores would increase to unsustainable levels. 

• No, the organisms of any trophic level cannot be removed without causing any damage to the ecosystem? It will disturb the food web and will create ecological imbalance.

Two problems caused by non-biodegradable waste that we generate in our daily life are: 

• It clogs drains. 
• It causes water and soil pollution.

CFCs are synthetic harmful chemicals which are mainly responsible for ozone layer depletion. CFCs release chlorine atoms which break ozone to oxygen. More amounts of CFCs thus released will cause depletion of ozone layer. CFCs are used as coolants in air-conditioners, refrigerators, aerosols sprays, fire extinguishers etc. 

Some effects of ozone depletion on living organisms are:

a. It causes skin cancer due to exposure to harmful UV radiations. 

b. Causes genetic variations due to mutations. 

c. Decreases photosynthetic rate in plants. 

d. Decrease immune power in humans and cause eyesight problem. 

e. It decreases crop yield. 

f. It also disturbs rainfall causing ecological disturbance and reduces global food production.

The CFC emission due to various industrial activities has caused damage to the Ozone layer and has contributed to global warming by allowing a major portion of UV rays to reach the earth’s atmosphere through ozone holes.

Forests help in preventing soil erosion / protect biodiversity / maintain groundwater level/help in rainfall / provide raw materials prevent floods/ (any other two points).

Exploitation by industries increase in population/ urbanization/cattle grazing / (any other two points)

Detailed Answer:

We must conserve our forests to conserve the biodiversity, ecological stability, habitat for wildlife, purify air and protect our Earth from greenhouse effect. 

Two factors responsible for causing deforestation :

(i) Over utilization of forest wood for human needs

(ii) Mining.

The compounds responsible for the depletion of ozone layer are chlorofluorocarbons (CFCs).

The impact of removing all the organisms in a trophic level be different for different trophic levels. Because if there are no producers no food is available to any organism. There is a deficiency of energy and creates imbalance in nature.

Non biodegradable wastes pollute the environment. They are:-

1. By these wastes Bio magnification takes place.

2. By these wastes large number of microbes are collected.

3. By consuming such food we get many diseases.

Chlorofluorocarbons (CFCs) are also called Freon. These compounds released into the atmosphere from spray cans, refrigerators, air conditioners. CFCs cause chemical reactions that break down ozone molecules. This causes reduction in absorption of ultraviolet radiation by ozone.

Carbon compounds which contain chlorine and fluorine are called CFCs (chlorofluorocarbons). e.g., CCl₂ F₂ (Dichlorodifluoromethane). They lead to depletion of ozone layer causing ozone hole. Nitric oxide also reacts with ozone to form NO₂ and O₂ CFCs (Chlorofluorocarbons) react with ozone in stratosphere and depletes ozone.

(i) It may lead to skin burns.

(ii) It may cause skin cancer.

The answer is (a) chlorofluorocarbon compounds

Crop fields are man-made and some biotic and abiotic components are manipulated by humans. Therefore, they are known as artificial ecosystems.

• Biological magnification occurs when the number of chemicals and toxins increase and accumulate through the trophic levels of a food chain.

• Chemical substances from crop fields and industries are released into the environment, making their way toward food chains and food webs. 

• Normally biological magnification doesn’t affect directly but exposure to these harmful chemicals may cause some long-term side effects.

The answer is (c) biomagnification

• Eutrophication is richness of nutrient beyond optimum level. 
• Eutrophication occurs due to run off from land. 
• Introduction of an undesired substance into environment. 
• Pollution leads to harmful effects on living organisms

Sunlight is the main source of energy for all the organisms in an ecosystem.

sun

Sun is the answer 

Correct answer is (d) All of them

1. b. Crop field

2. c. Communities of organisms interacting with one another

3. d. Producers consumers and decomposers

4. a. Aquariums

5. b. Aquarium

Ecosystem is the interactions among living (biotic) organisms, and non-living things (abiotic).

The answer is (b) Crop field

Crop field is a man made ecosystem.

The answer is (c) both living organisms and non-living objects 

An ecosystem is a complex of living and nonliving organisms and their interactions

Green plants are producers. The first trophic level in a food chain is a producers i.e. those organisms which produce food by photosynthesis.

The first trophic level is always a green plant because only plants can utilise the radiant energy of the sun and transform it to chemical form during photosynthesis.

1. No, it is not right to eradicate a living organism in an ecosystem. 

2. It disturbs the existing food chain.

The answer is (a) carnivores

First trophic level are producers, second tropic level are herbivores, third trophic level is occupied by carnivores.