Edexcel IAL Biology 8.8 Rod-cell phototransduction

Identify rhodopsin and its components, trace the light-triggered channel and potential change and connect altered transmitter release to optic-neurone impulses.

Exam points

Identify rhodopsin as the light-sensitive rod pigment formed from retinal and opsin.
Explain sodium-channel closure and rod-cell hyperpolarisation after light absorption.
Trace retinal change and rhodopsin splitting to altered optic-neurone signalling.

[Maximum number: 1]

The photograph shows the eyes of a meerkat.

Figure for Question 8.8—Rod cells and stimulus detection question 1 — Edexcel A-Level Biology A2

Photoreceptors stimulate nerve transmission in the eye.

Which of the following pairs of molecules forms the photoreceptor in an eye?

auxin and retinol

lysozyme and ribose

opsin and retinal

phytochrome and opsin

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8.8—Rod cells and stimulus detection question 1