The primary source of energy in an ecosystem is: MCQ with Answer and Explanation

The primary source of energy in an ecosystem is:
A. Moonlight
B. Wind
C. Geothermal energy
D. Sunlight
Answer: Option D
Solution (By JKSSB Mock Tests)
Sunlight is the ultimate source of energy for almost all ecosystems. Photosynthetic autotrophs (plants, algae, cyanobacteria) capture solar energy and convert it into chemical energy, which then flows through the food web. Some deep-sea ecosystems rely on chemosynthesis from hydrothermal vents, but globally, the sun drives the biosphere.

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Practice More Biology Questions

Question #1
The process by which the neural plate forms the neural tube during embryonic development is:
A. Cleavage
B. Gastrulation
C. Organogenesis
D. Neurulation

Correct Answer: Option D


Explanation:
Neurulation involves the folding of the neural plate to form the neural tube, which becomes the brain and spinal cord. Gastrulation forms germ layers.

This question belongs to: Science Biology
Question #2
The disorder caused by the deficiency of the enzyme phenylalanine hydroxylase is:
A. Maple syrup urine disease
B. Homocystinuria
C. Phenylketonuria
D. Albinism

Correct Answer: Option C


Explanation:
PKU leads to accumulation of phenylalanine, causing mental retardation. Albinism is tyrosinase defect, MSUD branched-chain ketoacid dehydrogenase, homocystinuria methionine metabolism.

This question belongs to: Science Biology
Question #3
Which structure is common to both prokaryotic and eukaryotic cells?
A. Ribosomes
B. Nuclear membrane
C. Mitochondria
D. Golgi apparatus

Correct Answer: Option A


Explanation:
Ribosomes are the only organelles common to both prokaryotes and eukaryotes, though sizes differ: 70S in prokaryotes, 80S in eukaryotes. Nuclear membrane, mitochondria, and Golgi are absent in prokaryotes. Ribosomes are the site of protein synthesis. This commonality supports the universal role of protein synthesis in all life forms. Mycoplasma, the smallest prokaryote, also has ribosomes.

This question belongs to: Science Biology