The myelin sheath around axons in the CNS is formed by: MCQ with Answer and Explanation

The myelin sheath around axons in the CNS is formed by:
A. Astrocytes
B. Schwann cells
C. Microglia
D. Oligodendrocytes
Answer: Option D
Solution (By JKSSB Mock Tests)
In the central nervous system, oligodendrocytes wrap axons forming the myelin sheath. In the peripheral nervous system, Schwann cells perform this function.

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Practice More Biology Questions

Question #1
The structure that connects the pharynx to the middle ear and equalizes pressure is the:
A. Auditory canal
B. Semicircular canals
C. Eustachian tube
D. Cochlea

Correct Answer: Option C


Explanation:
The Eustachian (auditory) tube connects the nasopharynx to the middle ear, allowing pressure equalization across the eardrum. The cochlea is for hearing, semicircular canals for balance.

This question belongs to: Science Biology
Question #2
The vitamin that is a component of the visual pigments in the retina is:
A. Vitamin E
B. Vitamin C
C. Vitamin D
D. Vitamin A

Correct Answer: Option D


Explanation:
Retinal (vitamin A aldehyde) is part of rhodopsin and cone pigments. Deficiency causes night blindness and xerophthalmia.

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Question #3
The pigment that gives brown algae their color is:
A. Phycoerythrin
B. Fucoxanthin
C. Phycocyanin
D. Chlorophyll b

Correct Answer: Option B


Explanation:
Fucoxanthin is a carotenoid that masks the green chlorophyll in brown algae (Phaeophyceae). Phycoerythrin is red, phycocyanin blue, chlorophyll b green.

This question belongs to: Science Biology