250+ TOP MCQs on Structure and Functions of an Ecosystem and Answers

Energy and Environment Management Questions and Answers for Freshers on “Structure and Functions of an Ecosystem”.

1. Which one of the following is not a gaseous biogeochemical cycle in an ecosystem?
a) Carbon cycle
b) Phosphorous cycle
c) Sulfur cycle
d) Nitrogen cycle
Answer: b
Clarification: Phosphorous cycle is not a gaseous biogeochemical cycle in an ecosystem. It is also a biogeochemical cycles but here atmosphere does not play a significant role in the movement of the phosphorous cycle.

2. Transfer of energy from source of plants through a series of organism is known as ________________
a) Food web
b) Energy cycle
c) Food chain
d) Biological system
Answer: c
Clarification: Food chain is a pathway that represents the exchange of energy from one organism to another. Energy is transmitted all the way from Sun to the other organisms by passing from producers to the consumers.

3. The type of ecosystem with the highest mean plant productivity is _______________
a) Tundra
b) Temperate grassland
c) Desert
d) Tropical rain forest
Answer: d
Clarification: A Tropical rain forest has more kinds of trees than any other area in the world. Seventy percent of the plants in the rainforest are trees. There are many distinct layers of trees. These layers have been identified as the emergent upper, canopy, understory and forest floor.

4. An ecosystem which can be easily damaged but can recovered after some time if damaging effect stops will be having ____________________
a) High stability and high resilience
b) High stability and low resilience
c) Low stability and low resilience
d) Low stability and high resilience
Answer: d
Clarification: In any ecosystem the condition of low stability and high resilience makes it to damage easily and after a certain amount of time they recover from damaging effects. Hence both stability and resilience play an important role in ecosystem.

5. Pyramids of number in grassland ecosystem are inverted.
a) True
b) False
Answer: b
Clarification: Pyramids of number in grassland ecosystem is erect. It is the graphical representation which depicts the number of organisms, biomass and productivity at each tropic level. All ecological pyramids begin at the bottom with the producer and goes into the upper level.

6. In ecosystem standing crop refers to________________
a) All the green plants
b) All the non living materials
c) All living and dead animals
d) All the living materials both animals and plants
Answer: d
Clarification: Standing crop is the amount of total biomass present in an ecosystem. This is the amount of total living matter. There is no circulation in standing crop. In standing crop continuous synthesis and consumption of biomass are going on.

7. Which ecosystem produce the highest annual net primary productivity?
a) Tropical evergreen forest
b) Tropical rain forest
c) Tropical deciduous forest
d) Temperate evergreen forest
Answer: b
Clarification: Tropical rain forest produce mean NPP of 2200(g/m2/yr) the world NPP is 37.4(109 tons/yr). Tropical rain forest produce mean biomass of 45(Kg/m2) and the world biomass is 763(109 tones). Hence tropical rain forest ecosystem produces the highest annual net primary productivity(NPP).

8. What flows through the ecosystem while matter cycles within them?
a) Energy
b) Force
c) Pressure
d) Wind
Answer: a
Clarification: Ecosystem maintains themselves by cycling energy and nutrients obtained from external sources. At the first tropic level, primary producers are solar energy to produce organic plant material through photosynthesis.

9. Total primary production in an ecosystem is known as____________________
a) Gross final production
b) Gross primary production
c) Gross middle production
d) Net primary production
Answer: b
Clarification: The total amount of productivity in a region is gross primary productivity. Primary productivity is the rate at which energy is converted by photosynthetic and chemosynthetic autotrophy to organic substances.

10. Which type of ecosystem accounts for most of the net primary productivity on earth even though it has a low average net primary productivity?
a) Tropical rain forest
b) Desert
c) Tropical evergreen forest
d) Oceans
Answer: d
Clarification: The open oceans account for most of the net primary productivity on the planet even though they have one of the lowest average net primary productivities which cover by far the most area on earth.

11. Generally ecosystem consists of how many basic components?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: Generally ecosystems consist of two basic components, they are abiotic and biotic components. Abiotic components include basic inorganic and organic compounds. Biotic components include producers, consumers and decomposers.

12. The three functional components interact with each other to form__________________
a) Environmental succession
b) Environmental depression
c) Environmental system
d) Ecology
Answer: c
Clarification: The three functional components of an ecosystem which are inorganic constituents, organism and energy input forms environmental system. An ecosystem is a functional and life sustaining environmental system.

13. The dominant second tropic level in a lake ecosystem is_____________________
a) Phytoplankton
b) Zooplankton
c) Plankton
d) Benthos
Answer: b
Clarification: Lake ecosystem includes both biotic and abiotic components. Zooplanktons are the organisms that have animal like traits. Most of them are heterotrophy in nature. Zooplankton is a vital component of fresh water food webs.

14. Green plants are the most important organisms for an ecosystem.
a) True
b) False
Answer: a
Clarification: Green plants form the basis for the sustainability and long term health of the environmental system. Green plant removes carbon dioxide from the atmosphere and generates oxygen required for breathing for other organisms include humans.

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