250+ TOP MCQs on Ecosystem – Energy Flow and Answers

Biology Multiple Choice Questions on “Ecosystem – Energy Flow – 1”.

1. What the only source of energy for all ecosystems on Earth?
a) Water
b) Sun
c) Plants
d) Animals
Answer: b
Clarification: The only source of energy for all ecosystems on Earth is the sun. The radiant light and heat from the sun is the primary, original source for most of the organisms and is used for the production of electricity, fuel, thermal energy, agriculture, etc.

2. Which is an exception in an ecosystem where the sun is not the source of energy?
a) Deep-sea hydro-thermal ecosystem
b) Terrestrial ecosystem
c) Lake ecosystem
d) Desert ecosystem
Answer: a
Clarification: The deep-sea hydro-thermal ecosystem is an exception in the ecosystem where the sun is not the source of energy. The chemosynthesis, marine snow, and whale falls are the three main sources of energy and nutrients for deep-sea communities.

3. What is the spectral range of solar radiation in that photosynthetic organisms are able to use in the process of photosynthesis called?
a) Photosynthetically Reactive Radiation
b) Photosynthetically Active Radiation
c) Photosynthetically Deactive Radiation
d) Photosynthetically Trapped Radiation
Answer: b
Clarification: The spectral range of solar radiation in that photosynthetic organisms are able to use in the process of photosynthesis is called as Photosynthetically Active Radiation. It is designated as PAR and ranges from 400nm to 700nm.

4. What percent of the incident solar radiation is photosynthetically active radiation (PAR)?
a) 100%
b) 85%
c) 20%
d) 50%
Answer: d
Clarification: Almost less than equal to the 50% of the incident solar radiation is photosynthetically active radiation (PAR). It ranges from 400nm to 700nm.

5. What percent of PAR is captured by plants?
a) 1%
b) 20-30%
c) 2-10%
d) 50%
Answer: c
Clarification: The spectral range of solar radiation that photosynthetic organisms are able to use in the process of photosynthesis is called PAR (400 to 700nm). Almost 2-10% of PAR is captured by plants.

6. On what are the organisms are dependent on their food?
a) Consumers
b) Producers
c) Decomposers
d) Scavengers
Answer: b
Clarification: All organisms directly or indirectly are dependent on producers for their food production. Producers are organisms that make their own food with the help of energy obtained from chemicals or the sun, water, and air. They are also known as autotrophs.

7. How is the flow of energy from the sun to producers and then to consumers?
a) Multidirectional
b) Bidirectional
c) No direction
d) Unidirectional
Answer: d
Clarification: The movement of energy from the higher trophic levels and its distribution and loss as heat to the lower trophic levels in the environment is unidirectional. It means the energy moves in one direction only that is from higher to the lower-most level.

8. From which law of energy the ecosystem are not exempted?
a) Zeroth law
b) First law of thermodynamics
c) Second law of thermodynamics
d) Fifth law of thermodynamics
Answer: c
Clarification: The ecosystems are not exempted from the Second Law of thermodynamics since they require a constant energy supply for synthesis of food. This increases the tendency toward disorderliness.

9. What are the green plants in the ecosystem termed as?
a) Scavengers
b) Consumers
c) Decomposers
d) Producers
Answer: d
Clarification: Usually the green plants present in the ecosystem are termed as the producers. Producers (autotrophs) are organisms that make their own food with the help of energy obtained from chemicals or the sun, water, and air.

10. Who are the major producers in a terrestrial ecosystem?
a) Phytoplankton
b) Zooplankton
c) Green plants
d) Birds
Answer: c
Clarification: The green plants (herbaceous and woody plants) are the major producers in a terrestrial ecosystem. Producers (autotrophs) are organisms that are capable of producing their own food (organic molecules) with the help of energy obtained from chemicals or the sun, water, and air (inorganic sources).

11. Who are the major producers in an aquatic ecosystem?
a) Zooplankton
b) Phytoplankton
c) Fungi
d) Bacteria
Answer: b
Clarification: Phytoplankton is the major producers in an aquatic ecosystem. Producers (autotrophs) are organisms that make their own food with the help of energy obtained from chemicals or the sun, water, and air.

12. How sunlight is much is reflected back out of the total sunlight reaching Earth?
a) 100%
b) 50%
c) 34%
d) 10%
Answer: c
Clarification: Almost 34 percent of light is reflected back out of the total sunlight reaching Earth. The heat and light from the sun is the original, primary source for most of the organisms and is used for the production of electricity, fuel, thermal energy, agriculture, etc.

13. How much percent of light reaches the Earth’s surface out of the total sunlight?
a) 20%
b) 56%
c) 0.1%
d) 30%
Answer: b
Clarification: Approximately 56-60 percent of light reaches the Earth’s surface out of the total sunlight. The heat and light from the sun is the original, primary source for most of the organisms and is used for the production of electricity, fuel, thermal energy, agriculture, etc.

14. What amount of sunlight is held the ozone layer, water vapor, and atmospheric gases out of total sunlight reaching Earth?
a) 50%
b) 8%
c) 20%
d) 10%
Answer: d
Clarification: 10% of sunlight is held the ozone layer, water vapor, and atmospheric gases out of total sunlight reaching Earth. The radiant light and heat from the sun is the primary, original source for most of the organisms.

15. What does this statement “The energy passed from producers to consumers (herbivores) does not go back to producers (autotrophs)” states about the flow of energy?
a) Flow is unidirectional
b) Flow has no specific direction
c) Flow is bidirectional
d) Flow is multidirectional
Answer: a
Clarification: The statement “The energy passed from producers to consumers (herbivores) does not go back to producers (autotrophs)” tells that the flow of energy is unidirectional. It means the energy moves in one direction only that is from higher to the lower-most level.