# CBSE Worksheet for Our Environment

## Questions: (1 mark each)

Question 1.
Suggest a food chain in which one of the trophic levels is occupied by human beings.
Question 2.
Draw the conclusion for if all the herbivores are removed from the grassland.
Question 3.
From the following list find out the organism which is likely to have maximum concentration of pesticide in its body: grass, grass- hopper, frog, snake and hawk.
Question 4.
Propose a way to dispose off vegetable peels, so that the environment is not polluted.
Question 5.
In an ecosystem, rats feed on grains. Name the trophic level to which the rats belong.
Question 6.
Name two chemicals which are responsible for thinning of ozone layer.
Question 7.
What is the function of zone in the upper atmosphere?
Question 8.
List two human- made (artificial) ecosystems.
Question 9.
Name two gases which have replaced CFCs.

## Questions: (2 marks each)

Question 1.
Aquarium needs to be cleaned once in a while whereas ponds or lakes do not require any cleaning. Explain.
Question 2.
Accumulation of harmful chemicals in our bodies can be avoided. Explain how this can be achieved.
Question 3.
What will happen if all the deers are removed in the given food chain?
Plants   →    deers  →    tigers
Question 4.
Explain the formation of ozone in the higher levels of atmosphere, giving relevant chemical equations.
Question 5.
There is a need to dispose waste in a proper manner. Justify this statement giving reasons.
Question 6.
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Question 7.
What is the role of decomposers in the ecosystem?
Question 8.
Give any two ways in which biodegradable substances would affect the environment.
Question 9.
Give any two ways in which non- biodegradable substances would affect the environment.
Question 10.
To protect the food plants from insects, an insecticide were sprayed in small amounts but it was detected in high concentration in human beings. How did it happen?
Question 11.
. What are the problems caused by the non- biodegradable wastes that we generate?
Question 12.
What will happen if we kill all the organisms in one trophic level?
Question 13.
What is biological magnification? Will the levels of the magnification be different at different levels of the ecosystem?
Question 14.
If all the waste we generate is biodegradable, will this have no impact on the environment?

## Multiple Choice Questions

Question 1.
. Disposable plastic plates should not be used because
(a) they are made of materials with light weight
(b) they are made of toxic materials

Question 2.
. In the following groups of materials, which group (s) contains only non-biodegradable items?
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelite, DDT
(a) (iii)
(b) (iv)
(c) (ii) and (iv)
(d) (i) and (iii)

Question 3.
. Which group of organisms are not constituents of a food chain?
(i) Grass, lion, rabbit, wolf
(ii) Plankton, man, fish, grasshopper
(iii) Wolf, grass, snake, tiger
(iv) Frog, snake, eagle, grass, grasshopper
(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iii)
(d) (i) and (iv)

Question 4.
. Excessive exposure of humans to U V-rays results in
(i) damage to immune system
(ii) damage to lungs
(iii) skin cancer
(iv) peptic ulcers
(a) (i) and (ii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) (i) and (iii)

Question 5.
. Depletion of ozone is mainly due to
(a) pesticides
(b) carbon monoxide
(c) methane
(d) chlorofluorocarbon compounds

Question 6.
. What percentage of solar energy is trapped and utilized by plants?
a. 1%
b. 10%
c. 5%
d. 2%

Question 7.
Which is of these not Natural Ecosystem?
a. Gardens
b. Aquariums
c. ponds
d. Lakes

Question 8.
The decomposers in an ecosystem
(a) convert inorganic material, to simpler forms
(b) convert organic material to inorganic forms
(c) convert inorganic materials into organic compounds
(d) do not breakdown organic compounds

Question 9.
If a grass hopper is eaten by a frog, then the energy transfer will be from
(a) producer to decomposer
(b) producer to primary consumer
(c) primary consumer to secondary consumer
(d) secondary consumer to primary consumer

Question 9.
Flow of energy in an ecosystem is always
(a) unidirectional
(b) bidirectional
(c) multi directional
(d) no specific direction
1. d
2. c
3. c
4. d
5. d
6. a
7. a,d
8. b
9. c
10. a

• NCERT solutions
• Assignments

### Practice Question

Question 1 Which among the following is not a base?
A) NaOH
B) $NH_4OH$
C) $C_2H_5OH$
D) KOH
Question 2 What is the minimum resistance which can be made using five resistors each of 1/2 Ohm?
A) 1/10 Ohm
B) 1/25 ohm
C) 10 ohm
D) 2 ohm
Question 3 Which of the following statement is incorrect? ?
A) For every hormone there is a gene
B) For production of every enzyme there is a gene
C) For every molecule of fat there is a gene
D) For every protein there is a gene