Igcse Model Questions Vol1 2019 Biology Question 20

Practice objective / multiple choice question 20 from the 2019 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2019 Biology Objective / Multiple Choice Medium Difficulty
Question 20 IGCSE_MODEL_QUESTIONS_VOL1 • 2019 • BIOLOGY • objective

A simple reflex arc consists of a sensory neuron, a single interneuron and a motor neuron. The measured total response time from stimulus to muscle contraction is 12 ms. The conduction velocities are 50 m s⁻¹ for the sensory neuron (which travels 0.20 m) and 60 m s⁻¹ for the motor neuron (which travels 0.30 m). Each chemical synapse introduces a delay of 0.5 ms.\ (a) Is the measured time consistent with the given parameters?\ (b) If not, calculate the additional delay required and state how many extra synaptic delays (each 0.5 ms) this corresponds to.

Answer Options

A. No; an extra 3 ms delay is needed, equivalent to six additional synaptic delays.
Correct Answer B. No; an extra 2 ms delay is needed, equivalent to four additional synaptic delays.
C. No; an extra 2 ms delay is needed, equivalent to three additional synaptic delays.
D. No; an extra 1 ms delay is needed, equivalent to two additional synaptic delays.
Correct Answer
B
Correct Option:
No; an extra 2 ms delay is needed, equivalent to four additional synaptic delays.

About This Question

This is Igcse Model Questions Vol1 2019 Biology Question 20. It is one of the objective questions from the 2019 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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