This set of Class 12 Biology Multiple Choice Questions & Answers (MCQs) focuses on “Ecosystem – Energy Flow – 5” for BDS-Dental Entrance Exam.
1. What are the food levels in an ecosystem called?
a) Decomposer level
b) Trophic levels
c) Producer levels
d) Consumer levels
View Answer
Explanation: The food levels in an ecosystem are alternatively called trophic levels. 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.
2. In general, a food chain consists of how many trophic levels?
a) Four
b) Zero
c) Two
d) One
View Answer
Explanation: In general a food chain consists of 3-4 trophic levels. Plants consists represent the first level, herbivores are in second. The carnivores and top carnivores come under the third and fourth trophic levels respectively.
3. How many trophic levels do green plants constitute?
a) Third trophic level
b) First trophic level
c) Last trophic level
d) Zero level
View Answer
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. Green plants are included in the first trophic level.
4. Who are the primary consumers of a biotic community?
a) Omnivores
b) Scavengers
c) Detritivores
d) Herbivores
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Explanation: Herbivores are said to be primary consumers of the biotic community. Producers (green plants) 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.
5. Which of the following organisms belong to the category of primary consumers?
a) Plants and phytoplankton
b) Eagle and snakes
c) Cattle and zooplankton
d) Fungi and beetles
View Answer
Explanation: Plants and phytoplankton belong to the category of primary consumers. Producers (primary consumers) 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.
6. What are decomposers?
a) Autotrophs
b) Heterotrophs
c) Parasites
d) Organotrophs
View Answer
Explanation: Decomposers are heterotrophs. The organisms that are responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances are called decomposers (detritivores).
7. A chicken has just eaten a worm. When a man sees this, he eats that chicken. To which trophic level does the man belong?
a) Secondary consumer
b) Primary consumer
c) Producer
d) Tertiary consumer
View Answer
Explanation: The organisms that cannot manufacture their own food and obtain ready-made organic food from producers are called consumers. Man belongs to the tertiary consumer level.
8. What will happen if we remove the decomposers from an ecosystem?
a) Energy flow stops
b) Consumers die
c) Mineralization will not occur
d) Plants won’t receive solar energy
View Answer
Explanation: If decomposers are removed from the ecosystem, the process of mineralization will stop. The process of release of inorganic substances both minerals (H2O, CO2, etc.) and non-minerals from organic matter (e.g. Ca2+, NH4, Mg2+, K+, etc.) is called mineralization. It is the last step in the process of decomposition.
9. Whose population is highest in an ecosystem?
a) Primary producers
b) Secondary consumers
c) Primary consumers
d) Decomposers
View Answer
Explanation: Producers (primary consumers) are organisms that make their own food with the help of energy obtained from chemicals or the sun, water, and air. Their population is highest in an ecosystem.
10. Which one of the following is the correct sequence of a grassland food chain?
a) Grass → Wolf → Bacteria → Deer
b) Grass → Deer → Fungi → Wolf
c) Grass → Deer → Wolf → Fungi
d) Grass → Fungi → Wolf → Deer
View Answer
Explanation: A food chain found in the grassland area is known as a grassland food chain. In this grass is the producer, deer is the herbivore, a wolf is a carnivore, and fungi are the decomposers.
11. Which one of the following is the correct sequence of an aquatic food chain?
a) Phytoplankton → Fishes → Fungi → Zooplankton
b) Phytoplankton → Zooplankton → Fishes → Fungi
c) Phytoplankton → Fungi → Zooplankton → Fishes
d) Zooplankton → Phytoplankton → Fishes → Fungi
View Answer
Explanation: A food chain found in any aquatic body is known as an aquatic food chain. In this phytoplankton is the producer, zooplankton is the herbivore, fish is the carnivore, and fungi are the decomposers.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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