Our environment Worksheet-14

Our environment Worksheet-14


  1. Give any two ways in which non-biodegradable substances would affect the environment.


  1. What is the role of decomposers in the ecosystem?


  1. What will happen if we kill all the organisms in one trophic level?


  1. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?


  1. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?


  1. If all the waste we generate is biodegradable, will this have no impact on the environment?


  1. (a) What is 'environmental pollution'?

(b) Distinguish between biodegradable and non­biodegradable pollutants.

(c) Choose the biodegradable pollutants from the list given below:

Sewage, DDT, radioactive waste, agricultural waste.


  1. How would you dispose the following wastes?

(i) Domestic wastes like vegetable peels.

(ii) Industrial wastes like metallic cans.

(iii) Plastic material.


  1. Write the cause of depletion of ozone layer in the atmosphere.


  1. What is ten per cent law? Explain with an example how energy flows through different trophic levels.


  1. "Vegetarian food habits can sustain a larger number of people." Justify the statement in terms of food chain.


  1. Name the radiations absorbed by ozone layer. Give any two causes of the depletion of the ozone layer. Name the disease likely to be caused due to depletion.


  1. With the help of an example, involving four organisms, describe how energy flows from different trophic levels?


  1. What is a food chain? Write a five-step food chain found in grassland with frog as one of its members. What will happen to the members at different trophic levels in the food chain if all the frogs in grassland were removed?


  1. What are decomposers? What role do they play in cycling of materials? How do the decomposers help in the replenishment of soil?


  1. What is a food chain? How does the study of food chain help us? Explain with two suitable examples, which food chains are advantageous in terms of energy?


  1. Differentiate between food chain and food web. Develop a food web on an ecosystem consisting of plants, mice, rabbits, grasshoppers, hawks, birds, snakes, insects and frogs.


  1. What is a food chain? How does study of food chain in an area or habitat help us? Give an example of four-step food chain operating in a large lake.


  1. Describe with a diagram how energy flows through different trophic levels. Describe how transfer and circulation of material takes place in nature, and the role of decomposers in the process. State how recycling of materials benefits living organisms.


  1. Why is the existence of decomposers essential in biosphere? Give two reasons.