Igcse Model Questions Vol1 2019 Biology Question 16
Practice objective / multiple choice question 16 from the 2019 Igcse Model Questions Vol1 Biology examination.
A reflex arc consists of a sensory neuron (unmyelinated) and a motor neuron (myelinated). The total length of the two neurons combined is 0.30 m, with the sensory neuron being twice as long as the motor neuron. The conduction velocity in a myelinated axon is given by \(v = 5d\) (m s⁻¹) where \(d\) is the fibre diameter in µm, and in an unmyelinated axon \(v = 0.6d\). The motor neuron's fibre diameter is 8 µm. The measured total time for the reflex impulse to travel from the receptor to the effector is 5 ms. Determine the fibre diameter of the sensory neuron (in µm, to three significant figures).
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This is Igcse Model Questions Vol1 2019 Biology Question 16. It is one of the objective questions from the 2019 Igcse Model Questions Vol1 Biology examination.
Difficulty level: Medium .
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