ReceptorsAQA A-Level Biology: Mind map

Exam questions on Receptors

1. Pacinian corpuscles are receptors found in the skin of the fingertips. Each one is the ending of a sensory neurone wrapped in several layers of connective tissue, with a gel between the layers.
   Suggest how the structure of the corpuscle allows pressure on the skin to produce a response in the sensory neurone.2 marks
2. A hiker walks at dusk. In the dim light she can make out the outline of the path and the trees but cannot tell what colour her jacket is. At midday she can read the fine print on her map and see colours clearly.
   Explain why she could not tell what colour her jacket was at dusk.2 marks
3. A researcher records the potential difference across the membrane of the sensory neurone ending inside a Pacinian corpuscle while different stimuli are applied. Light pressure produced a small depolarisation but no action potentials. Moderate pressure produced a larger depolarisation and a short series of action potentials in the sensory neurone. Strong pressure produced an even larger depolarisation and a more rapid series of action potentials, each the same size as before. A bright light shone on the corpuscle produced no change at all.
   Explain why strong pressure produced a larger depolarisation than light pressure.3 marks