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The myelin sheath around an axon is interrupted at regular intervals by small gaps. These gaps are called what?
ASynaptic knobs
BNodes of Ranvier
CNissl's granules
DPlasmodesmata
Answer & Solution
Correct answer: B. Nodes of Ranvier
1. The question asks for the regular gaps along the myelin sheath of an axon.
2. The myelin sheath insulates the axon but is broken at intervals.
3. Option A (synaptic knobs) are swellings at the very end of the axon, not gaps along it, a trap.
4. Option C (Nissl's granules) sit inside the cell body, not on the axon sheath.
5. Option D (plasmodesmata) are plant cell connections, unrelated to animal nerve cells.
6. The breaks along the myelin sheath are the Nodes of Ranvier.
7. So the answer is option B.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 15 Nervous System "Axon", p.226_
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