Same chapter3 marksDifficulty: Medium
Describe the structure of the human ear and the pathway of sound.
Neural Control and Coordination
3 marksDifficulty: Medium
Explain how a nerve impulse is generated and conducted along an axon.
Original Khojo Papers practice question — not from a past board paper.
Answer
At rest the inside of the axon is negative with respect to the outside, at about −70 mV, maintained by the sodium-potassium pump. A stimulus above threshold opens sodium channels and sodium rushes in, reversing the polarity to about +30 mV, which is depolarisation. Potassium then flows out and the resting potential is restored. The local circuit set up depolarises the next region, so the impulse travels along the axon.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
In a myelinated axon the impulse jumps between the nodes of Ranvier, which is much faster.
Related questions
From the same topic and chapter, at a similar level.
Same chapter3 marksDifficulty: Medium
Name the parts of the human brain and state one function of each.
Neural Control and Coordination
Same subject3 marksDifficulty: Medium
State three differences between gymnosperms and angiosperms.
Plant Kingdom
Same subject3 marksDifficulty: Medium
What are viruses, and why are they placed outside the five-kingdom system?
The Living World and Biological Classification
Same subject3 marksDifficulty: Medium
State three characteristics of bryophytes and name one example.
Plant Kingdom
Same subject3 marksDifficulty: Medium
Name the five kingdoms of Whittaker's classification and state the chief criterion for each.
The Living World and Biological Classification