Our environment Worksheet-15

Our environment Worksheet-15


  1. With the help of examples discuss in brief the role of decomposers in cycling of materials.


  1. Consider the following food chains:

(a) Plants  → Mice → Snakes → Hawks

(b) Plants → Mice → Hawks.

If energy available at the producer level in both the food chains is 100 J, in which case will Hawks get more energy as food and by what factor? Justify your answer.


  1. Consider the following food chains :

Grass → Mice → Snakes → Peacocks.

In this food chain if 100 J of energy is available at the producer level, then calculate the energy transferred to the peacocks as food. State the law used in the calculations.


  1. Calculate the amount of energy available to lion in the following food chain if plants have 20,000 J of energy available from the Sun : Plant → Deer →Lion


  1. Define food-chain and trophic level. State any two advantages of studying about food chain.


  1. Differentiate between a consumer and a producer. Give two examples of each.


  1. What is the difference between food chain and a food web? How do food chains get shortened? How does the shortening of food chain affect the biosphere?


  1. State one example of a food chain consisting of four organisms at different trophic levels. Name the scientific terms used to indicate these levels.


  1. How will you justify that "Vegetarian food habits give us more calories"? Represent it with the help of a 3-step food chain (Starting 10,00 J received by the plants).


  1. What is food web? Show its formation.


  1. Explain with an example, the accumulation of harmful chemicals through food chains. From where do these chemicals initially come?


  1. Explain ozone depletion with suitable example.


  1. How does the ozone layer protect us from harmful effects in the environment?


  1. Mention any three ill consequences of depletion of the ozone layer.


  1. Mention any six ecofriendly modes of waste disposal.


  1. What is ozone hole? Where is it located? How is it formed?


  1. Where is ozone layer found in atmosphere? What is its importance? Write the harmful effects of UV rays?


  1. How does harmful chemicals enter the food chain?


  1. Explain how carbon dioxide and ozone layer of the atmosphere are important to life.


  1. Describe giving two examples the process of biological magnification.


  1. What is ozone and how does it affect any ecosystem?


  1. How can you help in reducing the problem of waste disposal? Give any two methods.


  1. What are the problems caused by the non-biodegradable wastes that we generate?


  1. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?


  1. What is the difference between food chain and food web? Give suitable examples. Explain how harmful chemicals enter our bodies.


  1. A non-biodegradable toxic chemical has entered into the food chain. Which type of food habit will you suggest to a man, vegetarian or non-vegetarian? Explain with the help of a food chain. The food chain which you would suggest, is advantageous in an another aspect. How?


  1. What are chlorofluorocarbon? How are they responsible for causing ozone hole in atmosphere? What will be the consequences of ozone hole ?


  1. Write a note on the producers, consumers and decomposers of the biotic environment with examples of each.


  1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.