Our Environment MCQ
1. Which one of the following is an artificial ecosystem?
(a) Pond
(b) Crop field
(c) Lake
(d) Forest
Ans. (b) Crop field
Explanation: This ecosystem is created by humans.
2. In a food chain, the third trophic level is always occupied by
(a) carnivores
(b) herbivores
(c) decomposers
(d) producers
Ans. (a) carnivores
Explanation: First trophic level is occupied by producers and second is occupied by herbivores.
3. An ecosystem includes
(a) all living organisms
(b) non-living objects
(c) both living organisms and non-living objects
(d) sometimes living organisms and sometimes non-living objects
Ans. (c) both living organisms and non-living objects
Explanation: Both biotic and abiotic factors are present in an ecosystem.
4. In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level?
Grass →Grasshopper →Frog →Snake →Hawk
(a) 5 kJ
(b) 50 kJ
(c) 500 kJ
(d) 5000 kJ
Ans. (d) 5000 kJ
Explanation: Energy level available at a particular trophic level is 10 times the energy level at the next trophic level. Hence, third trophic level has 50 kJ, 2nd has 500 kJ and 1st has 5000 kJ.
5. Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as
(a) eutrophication
(b) pollution
(c) biomagnifications
(d) accumulation
Ans. (c) biomagnifications
6. Depletion of ozone is mainly due to
(a) chlorofluorocarbon compounds
(b) carbon monoxide
(c) methane
(d) pesticides
Ans. (a) chlorofluorocarbon compounds
7. Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called
(a) decomposers
(b) producers
(c) herbivores
(d) carnivores
Ans. (b) producers
Explanation: Producers use solar energy to make carbohydrates from water and carbon dioxides.
8. In an ecosystem, the 10% of energy available for transfer from one trophic level to
the next is in the form of
(a) heat energy
(b) light energy
(c) chemical energy
(d) mechanical energy
Ans. (c) Chemical energy
Explanation: Energy for the next trophic level is available in the form of food. Food contains chemical energy.
9. Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the
(a) food web
(b) ecological pyramid
(c) ecosystem
(d) food chain
Ans. (b) ecological pyramid
Explanation: In ecological pyramid, number of organisms at higher tropic level is always less than number of organisms at lower trophic level. An organism at higher trophic level usually feeds on more than one type of organisms.
10. Flow of energy in an ecosystem is always
(a) unidirectional
(b) bidirectional
(c) multi directional
(d) no specific direction
Ans. (a) unidirectional
Explanation: Flow of energy in an ecosystem is always from prey to predator and is never in the opposite direction.
11. 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) (i) and (iii)
(d) (iii) and (iv)
Ans. (c) (i) and (iii)
12. In the following groups of materials, which group (s) contains only nonbiodegradable items?
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelite, DDT
(a) (iii)
(b) (iv)
(c) (i) and (iii)
(d) (ii) and (iv)
Ans. (d) (ii) and (iv)
13. Which of the following limits the number of trophic levels in a food chain?
(a) Decrease in energy at higher trophic levels
(b) Deficient food supply
(c) Polluted air
(d) Water
Ans. (a) Decrease in energy at higher trophic levels
Explanation: Only 10% of the energy consumed by an organism at a particular trophic level is available for the organism at next trophic level. Hence by the time we reach the fourth trophic level; a minute portion of the energy from producer is available.
14. Which of the statement is incorrect?
(a) All green plants and blue green algae are producers
(b) Green plants get their food from organic compounds
(c) Producers prepare their own food from inorganic compounds
(d) Plants convert solar energy into chemical energy
Ans. (b) Green plants get their food from organic compounds
Explanation: Producers use solar energy to make carbohydrates from water and carbon dioxides. Water and carbon dioxide are inorganic compounds.
15. 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)
Ans. (c) (ii) and (iii)
Explanation: In option (ii) grasshopper does not eat plankton. In option (iii) none of the animals eats grass.
16. The percentage of solar radiation absorbed by all the green plants for the process
of photosynthesis is about
(a) 1 %
(b) 5 %
(c) 8 %
(d) 10 %
Ans. (a) 1%
Explanation: In a terrestrial ecosystem, green plants utilize about 1% of solar energy which falls on their leaves.
17. In the given Figure 15.1 the various trophic levels are shown in a pyramid. At which trophic level is maximum energy available?
(a) T4
(b) T2
(c) T1
(d) T3
Ans. (c) T1
Explanation: Maximum energy is available at the producer’s level.
18. What will happen if deer is missing in the food chain given below?
Grass →Deer →Tiger
(a) The population of tiger increases
(b) The population of grass decreases
(c) Tiger will start eating grass
(d) The population of tiger decreases and the population of grass increases
Ans. (d) The population of tiger decreases and the population of grass increases
Explanation: Population of tiger will decrease because of lack of food. Population of grass will increase because of lack of predators.
19. 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
Ans. (b) convert organic material to inorganic forms
20. If a grasshopper 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
Ans. (c) primary consumer to secondary consumer
Explanation: Grasshopper feeds on grass and hence is a primary consumer. Frogs feed on insects and hence are secondary consumers.
21. Disposable plastic plates should not be used because
(a) they are made of materials with light weight
(b) they are made of toxic materials
(c) they are made of biodegradable materials
(d) they are made of non-biodegradable materials
Ans. (d) they are made of non-biodegradable materials
Explanation: Because of their non-biodegradable nature, plastic keeps on accumulating in the environment.
