Exam-style Questions: Nervous and Hormonal Control

1. Serotonin is a neurotransmitter which is produced by certain neurones in the brain. One of its effects is to increase the activity of sensory neurones in the brain. It also usually improves a persons mood and keeps them awake. the diagram shows a synapse at which serotonin is the neurotransmitter.

Exam-style Questions

 

a) Explain how the release of the neurotransmitter serotonin, by neurone A would initiate an impulse in neurone B.

b) The serotonin is normally rapidly reabsorbed from the synaptic cleft by 5HT carrier proteins in the presynaptic membrane.

Suggest one advantage of rapidly reabsorbing the serotonin.

c) The active ingredient in the drug Ecstasy, is MDMA. MDMA blocks the attachment of serotonin molecules to the 5HT carrier proteins.

(i) suggest how MDMA may temporarily improve a persons mood.

(ii) MDMA may cause long term damage to the 5HT carrier proteins. This leads to a depressed mood. Suggest why.

(Marks available: 7)

Answer

 

Answer outline and marking scheme for question: 1

Give yourself marks for mentioning any of the points below:

a) Diffusion across cleft/to postsynaptic membrane.

Attachment to receptors.

Depolarisation/influx of sodium ions/change in permeability to ions.

Action potential produced/inside becomes more positive.

(max 3 marks)

b) Prevents continuing stimulation/prevents succession of action potentials/allows further transmission across synapse.

(1 mark)

c) (i) Serotonin stays in cleft/stays attached to receptors/not reabsorbed.

Continues to produce action potentials/impulses to stimulate 'mood enhancing centre'.

(ii) Reduced supply of serotonin.

(3 marks)

(Marks available: 7)

 

2. The diagram shows some of the events which occur in a synapse after the arrival of an impulse at the presynaptic membrane.

Exam-style Questions

 

a) Put the events 1-6 on the diagram in the correct sequence.

b) Name the ions labeled A and B.

c) Name one transmitter molecule released by synaptic vesicles.

(Marks available: 4)

Answer

 

Answer outline and marking scheme for question: 2

Give yourself marks for mentioning any of the points below:

a) Correct order is 316425:

Movement of ions through membrane.

Vesicle fuses to membrane

Vesicle releases transmitter molecules.

Transmitter molecule attaches to receptor site.

Movement of ions through membrane.

Postsynaptic membrane depolarises.

(1 mark)

b) A= Calcium.

B = Sodium

(2 marks)

c) Noradrenaline/acetylcholine.

(1 mark)

(Marks available: 4)

 

3. One example of homeostasis is the regulation of blood pressure. If there is a fall in blood pressure, nerve impulses are sent from receptors in the walls of the heart and associated blood vessels to the brain. As a result, nerves of the autonomic nervous system are stimulated and impulses are sent to the heart to control its rate of beating.

a) Which region of the brain controls the heart rate?

b) Describe the role of the autonomic nervous system in controlling heart rate.

(Marks available: 4)

Answer

 

Answer outline and marking scheme for question: 3

Give yourself marks for mentioning any of the points below:

a) Medulla; medulla oblongata.

(1 mark)

(b) Reference to: sympathetic and parasympathetic systems.

Antagonistic effect.

Sympathetic speeds up heart/parasympathetic slows heart down.

Acts on SAN.

(3 marks)

(Marks available: 4)