Photoreception in rod cellsEdexcel International A Level Biology: Flashcards

What these 12 flashcards ask

What is rhodopsin made of?
What happens to retinal when it absorbs light?
What is the state of the cation channels in a rod cell in the dark?
What is the membrane potential of a rod cell in the dark?
What does a rod cell release in the dark?
What happens to the cation channels when rhodopsin is broken down?
What is hyperpolarisation?
Why does the rod release less neurotransmitter in the light?
How does the bipolar neurone become depolarised in the light?
What is produced in the optic neurone when the bipolar neurone depolarises?
Why is it hard to see in dim light after leaving bright light?
Where are rod cells found?

Exam questions on Photoreception in rod cells

A vision scientist is recording the membrane potential of a single rod cell taken from the retina of a dark-adapted animal. She records first in complete darkness and then when a brief flash of light is delivered.
Describe what happens to rhodopsin when a rod cell absorbs light.2 marks
In a further experiment the scientist exposes a dark-adapted rod cell to a dim flash of light and measures changes in the rod cell and in the bipolar neurone that it synapses with.
Explain why absorption of light causes the rod cell membrane to become hyperpolarised.2 marks
A driver leaves a brightly lit road tunnel and enters a poorly lit country lane at night. For several minutes she can see almost nothing, but her vision then slowly improves.
Describe how absorption of light by rod cells in the driver's retina leads to an action potential in an optic neurone.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).