Which of the following organisms is a decomposer in an ecosystem? MCQ with Answer and Explanation

Which of the following organisms is a decomposer in an ecosystem?
A. Lion
B. Eagle
C. Fungi
D. Grass
Answer: Option C
Solution (By JKSSB Mock Tests)
Fungi (and bacteria) are decomposers that break down dead organic matter and waste, releasing nutrients back into the ecosystem. They are saprotrophs. Grass is a producer, lion and eagle are consumers (carnivores). Decomposers are essential for nutrient cycling, especially carbon and nitrogen cycles. Without decomposers, ecosystems would be clogged with dead material.

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Practice More Biology Questions

Question #1
The structure that provides buoyancy to aquatic plants is:
A. Xylem
B. Collenchyma
C. Aerenchyma
D. Sclerenchyma

Correct Answer: Option C


Explanation:
Aerenchyma is a specialized parenchyma tissue with large intercellular air spaces, providing buoyancy and facilitating gas exchange in aquatic plants. It also helps in oxygen transport to submerged roots. Sclerenchyma is supportive, collenchyma flexible support, xylem water-conducting.

This question belongs to: Science Biology
Question #2
The term used for organisms that can synthesize their own food from inorganic substances is:
A. Parasites
B. Autotrophs
C. Saprotrophs
D. Heterotrophs

Correct Answer: Option B


Explanation:
Autotrophs (self-feeders) include photoautotrophs (plants, algae, cyanobacteria) and chemoautotrophs (some bacteria). They produce organic matter from CO₂. Heterotrophs depend on others, saprotrophs decompose dead matter, parasites live on hosts.

This question belongs to: Science Biology
Question #3
The vitamin that is required for the synthesis of ATP from ADP is:
A. Riboflavin
B. Niacin
C. Thiamine
D. Pantothenic acid

Correct Answer: Option B


Explanation:
Niacin is part of NAD⁺/NADH, which donates electrons to the electron transport chain to generate the proton gradient for ATP synthesis. All B vitamins contribute indirectly.

This question belongs to: Science Biology