Biology Questions and Answers – Ecosystem – Energy Flow – 3

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This set of Biology MCQs for BDS-Dental Entrance Exams focuses on “Ecosystem – Energy Flow – 3”.

1. What is the missing level?
? → Heterotrophs → Decomposer?
a) Carnivore
b) Autotrophs
c) Scavengers
d) Humans
View Answer

Answer: b
Explanation: The missing level in the above question is autotrophs. 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.
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2. What is the missing level?
Autotrophs → ? → Decomposer
a) Heterotrophs
b) Carnivore
c) Producer
d) Scavengers
View Answer

Answer: a
Explanation: The missing level in the above question is heterotrophs. The organisms that cannot manufacture their own food and obtain ready-made organic food from producers are called consumers. These are the heterotrophic organisms.

3. What is the missing level?
Autotrophs → Heterotrophs → ?
a) Producer
b) Decomposers
c) Scavengers
d) Plants
View Answer

Answer: b
Explanation: The missing level in the above question is decomposers. The organisms that are responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances are called decomposers (detritivores).
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4. Which is the missing level of the organization?
Autotrophs → Herbivores → Carnivores → ? → Decomposers
a) Producers
b) Detritivores
c) Scavengers
d) Top carnivores
View Answer

Answer: d
Explanation: The missing level in the above question is the top carnivores. These are the organisms that feed on lower carnivores for food and nutrition. An example is a snake who feeds on a frog who is feeding on an insect.

5. Which organisms form trophic levels in an ecosystem?
a) Only bacteria
b) Only plants
c) Organisms linked in the food chain
d) Only consumers
View Answer

Answer: c
Explanation: The step or division that organisms occupy in a food chain that is characterized by the method of obtaining their nutrition to fulfill their energy requirements is known as a trophic level. Various organisms linked in the food chain form trophic levels in an ecosystem.
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6. What amount of sunlight is used for photosynthesis?
a) 10%
b) 0.02%
c) 2%
d) 80%
View Answer

Answer: b
Explanation: The amount of sunlight, out of total sunlight reaching on the Earth used for photosynthesis is 0.02 percent. Photosynthesis is a process in which producers (green plants) in the presence of CO2, water, sunlight, and chlorophyll yield energy and oxygen is released in the form of gas.

7. During the flow of energy in an ecosystem, in which form is the energy dissipated during various metabolic activities?
a) Ammonia
b) Vapours
c) Photons
d) Heat
View Answer

Answer: d
Explanation: During the flow of energy in an ecosystem, the energy is dissipated in the form of heat during several metabolic activities. Heat is a result of cell respiration, a form of energy that is not used in an ecosystem and released in an abiotic environment.
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8. Which is the missing organism?
Detritus → ? → Frog → Snake → Peacock
a) Elephant
b) Tiger
c) Earthworm
d) Ostrich
View Answer

Answer: c
Explanation: The missing level of an organization is an earthworm that is a decomposer. The organisms that are responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances are called decomposers (detritivores).

9. What is a grazing food chain alternatively called?
a) Parasitic food chain
b) Detritus food chain
c) Auxiliary food chain
d) Predator food chain
View Answer

Answer: d
Explanation: A food chain consisting of autotrophs (producers), heterotrophs, and carnivores (consumers) is known as a grazing food chain. It is alternatively known as the predator food chain. It is the most common food chain and is designated as GFC.
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10. What percent of energy is transferred in a food chain from one trophic level to another?
a) 35%
b) 20%
c) 10%
d) 54%
View Answer

Answer: c
Explanation: The amount of energy transferred from organic matter in a food chain from one trophic level to another is 10 percent. In a food chain, some amount of energy is consumed by the organism itself, some energy is transferred to another organism while the energy not utilized is lost in the form of heat.

11. Which law states that there is a transfer of 10 percent energy in a food chain from one trophic level to another?
a) Blackman Law
b) 10 percent law
c) Hardy Weinberg principle
d) Mendel’s law
View Answer

Answer: b
Explanation: The amount of energy transferred from organic matter in a food chain from one trophic level to another is 10 percent. This is stated in a law known as ‘10% law’. It tells that the energy transferred from organic matter is stored in the form of flesh.

12. Which of the following consumers belong to the third level of energy flow?
a) Herbivores
b) Top carnivores
c) Carnivores
d) Decomposers
View Answer

Answer: c
Explanation: The carnivores are the organisms that primarily and exclusively feed on other animals (herbivore or carnivore) for energy. They may occupy 2-3 trophic levels in an ecosystem.

13. What do we study in ecological energetics?
a) Amount of air reaching Earth
b) Quantity and path of energy flow from producers to consumers
c) Amount of vacuum in the universe
d) Quality of energy used by green plants for photosynthesis
View Answer

Answer: b
Explanation: In ecological energetics (production ecology) we study the quantity and path of energy flow from producers to consumers. It is the amount of energy that entered in a living system until it is ultimately degraded to heat and is lost irreversibly from the system at a specific time.

14. Who formulated the 10% law of a food chain?
a) Blackman
b) Ernst Rutherford
c) Gregor Mendel
d) Raymond Lindemann
View Answer

Answer: d
Explanation: The amount of energy transferred from organic matter in a food chain from one trophic level to another is 10 percent. This is stated in a law known as ‘10% law’. It was given by Raymond Lindemann in 1942.

15. How should be the food chain so that a greater amount of energy is available for top consumers?
a) Shorter
b) Longer
c) Moderate
d) Neutral
View Answer

Answer: a
Explanation: A food chain should be shorter so that a greater amount of energy is available for top consumers. Since more and more energy is lost while going to the next trophic level, the shorter food chain is more efficient because less energy is lost to the surroundings.

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