exam questions

Question 1

animals receive different stimuli from their environment

their synapses can manage multiple stimuli, often
resulting in one response (such as a muscle twitching)

this action of the synapse is an example of? (1)

Answer 1

spatial summation

Question 2

what best describes the membrane during repolarisation (1)

Answer 2

sodium ion channels: closed
potassium ion channels: open
membrane potential: decreases

Question 3

why is the pacinian corpuscle described as a transducer? (1)

Answer 3

converts mechanical energy into a form of kinetic energy

Question 4

deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to Na+ ions

suggest why (1)

Answer 4

1. increased pressure causes sodium ion channels to open
2. gaps appear in phospholipid bilayer

Question 5

the generation of an action potential follows the ‘All-or-Nothing’ law

explain what this means (1)

Answer 5

if a threshold potential is not reached than an action potential cannot be generated

Question 6

describe how information about the strength and intensity of a stimulus is communicated to the brain (2)

Answer 6

1. represented by the frequency of action potentials
2. high frequency of action potentials shows a strong stimulus

Question 7

when clothes are first put on the body, a constant gentle pressure is applied to the pressure receptors in the
skin

after a short time, action potentials are no longer generated unless there is a change in pressure as the
clothes move over the surface of the skin

suggest an explanation for the fact that action potentials are not generated constantly whilst wearing clothes (1)

Answer 7

1. resting potential is not reestablished
2. ions are in the wrong place for movement across the membrane

Question 8

synapses are an integral part of the nervous system

outline the roles of synapses in the nervous system (3)

Answer 8

1. allows neurons to communicate
2. ensures transmission in only one direction
3. allows convergence and divergence impulses
4. allows many low level stimuli to be amplified

Question 9

name one chemical that transfers a nerve impulse from one neurone to another (1)

Answer 9

acetyl choline

Question 10

paracetamol is a drug that is commonly used as a painkiller. for many years, scientists have been uncertain
about the way in which paracetamol works.

a recent study has shown that:

1. paracetamol is broken down in the spinal cord into a compound called NAPQI
2. NAPQI activates a receptor protein called TRPA1
3. TRPA1 is found on the plasma (cell surface) membranes of neurones
4. the activated receptor protein, TRPA1, interferes with the transmission of the nerve impulses from one
   neurone to the next

suggest the part of the neurone where the plasma membrane has TRPA1 receptors.
explain your answer (2)

Answer 10

1. post synaptic membrane

TRPA1 prevents attachment of neurotransmitter to its receptor

2. pre synaptic membrane

TRPA1 prevents release of neurotransmitter and an influx of calcium ions

Question 11

where are acetylcholine receptors found (1)

Answer 11

post synaptic membrane