Igcse Model Questions Vol1 2023 Biology Question 37

Practice objective / multiple choice question 37 from the 2023 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2023 Biology Objective / Multiple Choice Medium Difficulty
Question 37 IGCSE_MODEL_QUESTIONS_VOL1 • 2023 • BIOLOGY • objective

A simple reflex arc involves a sensory neuron that conducts an impulse 0.5 m to the spinal cord at a speed of 80 m s\(^{-1}\), and a motor neuron that conducts the impulse 0.4 m to a muscle at 60 m s\(^{-1}\). Each synapse in the pathway introduces a delay of 0.5 ms. (a) Calculate the total time from the initial stimulus to the onset of muscle contraction. (b) If the measured reflex time is 12 ms, discuss whether the calculated time is consistent and what this implies about the number of synapses or conduction speeds.

Answer Options

Correct Answer A. Total calculated time ≈ 13.9 ms; because the observed reflex is 12 ms, the pathway likely has fewer synapses or higher conduction speeds.
B. Total calculated time ≈ 13.9 ms; because the observed reflex is 12 ms, the pathway likely has more synapses or lower conduction speeds.
C. Total calculated time ≈ 11.5 ms; because the observed reflex is 12 ms, the pathway likely has additional synapses or slower conduction speeds.
D. Total calculated time ≈ 15.2 ms; because the observed reflex is 12 ms, the pathway likely has fewer synapses or higher conduction speeds.
Correct Answer
A
Correct Option:
Total calculated time ≈ 13.9 ms; because the observed reflex is 12 ms, the pathway likely has fewer synapses or higher conduction speeds.

About This Question

This is Igcse Model Questions Vol1 2023 Biology Question 37. It is one of the objective questions from the 2023 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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