1. What are trophic levels? Give an example of a food chain and
state the different trophic levels in it.
Answer:
In food chain, the transfer food or energy takes place at the
various levels and these levels are known as trophic levels.
Example:
Grass → Goat → Man
In food chain,
Grass represents the first trophic level
Goat represents the second trophic level
Man represents the third trophic level
2. What is the role of decomposers in the ecosystem?
Answer:
Following is the role of a decomposer in the ecosystem:
They act as a cleansing agents of the environment by decomposing
the dead plants and animals
They help in recycling the nutrients
They provide space for new being in the biosphere by decomposing
the dead
They help in putting back the various elements into water, soil
and air for the reuse of producers like crop plants.
1. Why are some substances biodegradable and some
non-biodegradable?
Answer:
The reason why some substances are biodegradable and some
non-biodegradable is because the microorganisms like bacteria and decomposers
like saprophytes have a specific role to play. They can breakdown only natural products
like paper, wood etc. but they cannot breakdown man-made products like
plastics. Based on this some substances are biodegradable and some
non-biodegradable.
2. Give any two ways in which biodegradable substance would affect
the environment.
Answer:
Following are the ways in which biodegradable substance would
affect the environment:
They keep the environment clean as they are easily decomposed.
They can easily go through the geo-chemical cycle with the help
of decomposers.
3. Give any two ways in which non-biodegradable substance would
affect the environment.
Answer:
Following are the ways in which non-biodegradable substance would
affect the environment:
They cause air, soil and water pollution.
They may cause bio-magnification in the food chain resulting in
end of human.
Questions
1. What is ozone and how does it affect the ecosystem?
Answer:
Ozone is a molecule formed by the three atoms of oxygen and is
known as an isotope of oxygen. The main function of ozone layer is to provide
protection to the earth’s surface from the harmful UV rays of the sun. These
rays are harmful to living organisms and may result in skin cancer.
2. How can you help in reducing the problem of waste disposal?
Give any two methods.
Answer:
Following are the ways to reduce the problem of waste disposal:
(a) 3 R’s: By following the 3 R’s one can reduce the problem of
waste disposal. The 3 R’s are reduce, recycle
and reuse. Reducing the usage of own vehicles and opting for
public transport can reduce the air pollution.
Recycling and reusing of plastics is also a way to reduce the
waste disposal.
(a)
Preparation of compost: All the biodegradable wastes like kitchen
waste, can be dumped in the compost.
Questions
1. Which of the following groups contain only biodegradable items?
a) Grass, flowers and leather
b) Grass, wood and plastic
c) Fruit peels, cake and lime juice
d) Cake, wood and grass
Answer:
a) Grass, flowers and leather c) Fruit peels, cake and lime juice
d) Cake, wood and grass
Above all are the groups that contain only biodegradable items.
Since plastic is not a biodegradable substance, that group cannot be considered
as a biodegradable.
2. Which of the following constitute a food-chain?
a) Grass, wheat and mango
b) Grass, goat and human
c) Goat, cow and elephant
d) Grass, fish and goat
Answer:
b) Grass, goat and human
Here, goat is the producer, goat is the primary consumer and human
is the secondary consumer.
3. Which of the following are environment-friendly particles?
a) Carrying cloth bags to put purchases in while shopping
b) Switching off unnecessary lights and fans
c) Walking to school instead of getting your mother to drop you on
her scooter
d) All of the above
Answer:
All of the above
4. What will happen if we kill all the organisms in one trophic
level?
Answer:
If we kill all the organisms in one trophic level, the food supply
to the next level will strop resulting in imbalance of the ecosystem. As a
result animals in the higher levels will die making the growth of animals in
lower trophic level increase in an enormous way. All of this will affect the
overall balance in the ecosystem.
5. Will the impact of removing all the organisms in trophic level
be different for different trophic levels? Can the organisms of any trophic level
be removed without causing any damage to the ecosystem?
Answer:
Yes, the impact of removing all the organisms in a tropic level
will be different for different trophic levels. For example, if all the
producers are removed, there is a chance of death or migration of the primary consumers
which will upset the trophic levels. This is same for all the levels.
Therefore, removal of organisms at any level would upset the whole ecosystem as
the food chain is disturbed. The survival of the higher level animals is
completely dependent on the animals at the lower levels.
6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer:
Biological magnification can be defined as the progressive increase in the concentration of nonbiodegradable wastes in the food chain. As there is an increase in the magnification at the primary level of the ecosystems, all the other levels do get affected and the concentration may vary when compared to first level.
7. What are the problems caused by the non-biodegradable wastes
that we generate?
Answer:
Following are the problems caused by the non-biodegradable wastes:
These substances cannot be decomposed by the microorganisms.
As the quantity increases, dumping becomes a problem.
Non-biodegradable wastes like heavy metals may enter the food
chain in the upper trophic levels.
They may escape to the ground water which causes soil infertility
and disturbance in pH of the soil.
8. If all the waste we generate is biodegradable, will this have
no impact on the environment?
Answer:
Biodegradable wastes are decomposed by the microorganisms into simpler substances which can be used by the producers as a raw material. But following are the effects of too much of biodegradable wastes:
- As the decomposition of the biodegradable wastes are slow, they produce awful smell and when inhaled by humans it can be harmful.
- The dumping areas can be a place where harmful organisms may start to breed which can be harmful to humans as well as plants and animals.
- Increase in the number of aquatic organisms may result in
depletion of oxygen.
9. Why is damage to the ozone layer a cause for concern? What
steps are being taken to limit this damage?
Answer:
Ozone layer is a protective cover for the earth. It prevents harmful UV rays from entering the earth as these rays harmful and can result in skin cancer. But the air pollutants like chlorofluorocarbons (CFCs) are the main reason for the depletion of the ozone layer. Too much of UV rays are harmful for plants as they affect the photosynthesis, destroy planktons and decomposers. These are the reasons why damage of ozone layer a cause of concern.
Steps taken to limit is many developing and developed countries have signed and are obeying the directions of TINEP (United Nations Environment Programme) to freeze or limit the production and usage of CFCs
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