Class 10 Science Chapter 13 Question Answers - Our Environment

Q1: Give an example each of natural and an artificial ecosystem.
Ans:

• Natural ecosystem : Forest or pond
• Artificial ecosystem : Crop field or aquarium.

Q2: What is the full form of CFCs and UNEP?
Ans:

• CFC = Chlorofluorocarbons
• UNEP = United Nations Environment Programme.

Q3: Define ecosystem and name its components.
Ans: The living and non-living components of an area interact with each other to form an ecosystem. Components of ecosystem are: Biotic (living) and abiotic (non-living)

Q4: What is the role of ozone? Why is it being depleted?
Ans: Ozone protects us from harmful UV radiations. It is being depleted due to excess use of chlorofluorocarbons (CFCs).

Q5: What is ten per cent law?
Ans: Ten per cent law states that only 10% of the energy available at a trophic level is transferred to the next trophic level.

Q6: List two advantage of decomposers to the environment.  [CBSE 2008]
Ans: Advantage of decomposers:

• They replenish the soil nutrients.
• They help to clean the environment by degrading the dead remains of plants and animals.

Q7: What is the ultimate source of energy in an ecosystem? Which process helps to trap this energy in producers?
Ans: Sun is the ultimate source of energy in an ecosystem. Photosynthesis helps to trap this energy in producers.

Q8: What is the major cause of ozone depletion? Where are these substances used?  [CBSE 2012]
Ans: Chlorofluorocarbons are major cause of ozone depletion. They are used in refrigerator and aerosol sprays.

Q9: Why should biodegradable and non-biodegradable wastes to be discarded in two separate dustbins?  [CBSE 2015]
Ans: Biodegradable and non-biodegradable waste should be discarded in two separate dustbins as it will make it easier to recycle the recyclable wastes. This will also save time and energy.

Q10: What will happen if we kill all the organisms in one trophic level?  [CBSE 2011]
Ans: Killing all the organisms in one trophic level would decrease availability of food at the next trophic level and also result in excess of organisms at the previous trophic level. This would cause an imbalance in the food chain.