NCERT Solutions for Class 10 Science Ch 13: Our Environment, is given below.
You will get solutions for;
- In-text questions as well as,
- Exercises questions.
So let’s dive into it!
In-text Questions Set-1
1) What are the trophic levels? Give an example of a food chain and state the different trophic levels in it.
Solution:
In a food chain, energy moves through different levels called trophic levels. For example:
Grass → Goat → Man
Here is the break down in food chain:
– Grass is the first trophic level.
– The goat is the second trophic level.
– Man is the third trophic level.
2) What is the role of decomposers in the ecosystem?
Solution:
Decomposers play several important roles in the ecosystem:
– They clean the environment by breaking down dead plants and animals.
– They recycle nutrients, helping to renew the soil.
– They create space for new organisms by decomposing the old ones.
– They return essential elements to the water, soil, and air, which helps plants and other producers grow.
In-text Questions Set-2
1) Why are some substances biodegradable and some non-biodegradable?
Solution:
Some substances are biodegradable because microorganisms, like bacteria and decomposers, can break them down. They can decompose natural materials like paper and wood, but they can’t break down human-made materials like plastics. This is why some substances can be decomposed by nature, while others cannot.
2) Give any two ways in which biodegradable substances would affect the environment.
Solution:
Biodegradable substances benefit the environment in these ways:
– They help keep the environment clean because they break down easily.
– They easily move through the geochemical cycle with the help of decomposers.
3) Give any two ways in which non-biodegradable substances would affect the environment.
Solution:
Non-biodegradable substances can harm the environment in the following ways:
– They pollute the air, soil, and water.
– They can lead to bio-magnification in the food chain, which could eventually harm humans.
In-text Questions Set-3
1) What is ozone, and how does it affect the ecosystem?
Solution:
Ozone is a molecule made up of three oxygen atoms and is a type of oxygen. The ozone layer protects Earth’s surface by blocking harmful UV rays from the sun. These rays can be dangerous to living organisms and may cause skin cancer.
2) How can you help in reducing the problem of waste disposal? Give any two methods.
Solution:
Here are some simple ways to tackle waste disposal problems:
– Follow the 3 Rs: Reduce, Reuse, and Recycle. For example, using public transport instead of private vehicles helps cut down on air pollution. Recycling and reusing plastics also help manage waste.
– Make Compost: You can turn biodegradable waste, such as kitchen scraps, into compost. This helps reduce the amount of waste sent to landfills.
Exercise 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
Solution:
(a) Grass, flowers and leather
(c) Fruit peels, cake and lime juice
(d) Cake, wood and grass
Since plastic is not a biodegradable substance, that group cannot be considered biodegradable.
2) Which of the following constitutes a food chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Solution:
(b) Grass, goat and human
3) Which of the following are environment-friendly practices?
(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
Solution:
(d) All of the above
4) What will happen if we kill all the organisms at one trophic level?
Solution:
If we remove all the organisms from one trophic level, it will cut off the food supply to the next level. This disruption will cause the animals higher up to die and lead to a rapid increase in the animals at the lower level. This imbalance will upset the entire ecosystem.
5) Will the impact of removing all the organisms in the trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Solution:
Removing all the organisms at a specific trophic level affects the entire ecosystem differently, depending on which level is removed. For example, if all the producers are gone, primary consumers might die or move away, disrupting the balance of the food chain.
This pattern holds true for any trophic level. Essentially, removing organisms from any level throws off the whole ecosystem because each level relies on the ones below it for survival.
6) What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Solution:
Biological magnification is the process where the concentration of non-biodegradable wastes increases as you move up the food chain. As you go higher in the food chain, each level accumulates more of these wastes, which can affect all the levels below it.
7) What are the problems caused by the non-biodegradable wastes that we generate?
Solution:
Here are the problems caused by non-biodegradable waste:
– These materials cannot be broken down by microorganisms.
– As the amount increases, disposal becomes difficult.
– Non-biodegradable wastes, such as heavy metals, can enter the food chain and affect animals at higher levels.
– They can contaminate groundwater, leading to soil infertility and changes in soil pH.
8) If all the waste we generate is biodegradable, will this have no impact on the environment?
Solution:
Biodegradable waste is broken down by microorganisms into simpler substances that producers can use as raw materials. However, too much biodegradable waste can cause several problems:
– Decomposition of these wastes happens slowly and can produce a foul smell that is harmful if inhaled.
– Dumping areas for these wastes can attract harmful organisms that pose risks to humans, plants, and animals.
– A high amount of biodegradable waste in water can lead to oxygen depletion, affecting aquatic life.
9) Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Solution:
The ozone layer protects the Earth by blocking harmful UV rays that can cause skin cancer. However, air pollutants like chlorofluorocarbons (CFCs) are damaging the ozone layer. Too many UV rays can harm plants by disrupting photosynthesis and destroying plankton and decomposers.
This is why ozone layer damage is a major concern. To address this issue, many countries, both developing and developed, are following guidelines from the United Nations Environment Programme (UNEP) to reduce or stop the production and use of CFCs.