Question: 1

This question is about types of muscle and how the nervous system and hormones control their activity.

(a) There are three types of muscle within the human body. These differ in their cellular structure and in their function.

Complete Table 2.1 to show how each type of muscle differs from the other two types.

[6]

(b) The human thorax is the area between the base of the neck and the base of the rib cage. All three types of muscle can be found within this area.

For each type of muscle, identify where in the thorax this type of muscle may be found.

Voluntary

Involuntary

cardiac

[3]

(c) Fig. 2.1 shows a vertical section through the human brain.

Use Fig. 2.1 to state the letter (B to E) of the part of the brain that would be involved in the following:

adjusting the rate of contraction of cardiac muscle

clapping the hands together

automatically correcting balance when riding a bicycle

[3]

(d) Movement disorders are conditions in which people lose the ability to control their body movements.

Scientists have discovered that inserting electrodes to stimulate parts of the brain can help to cure some movement disorders. This discovery has resulted from experimental work with monkeys, which has made the research controversial.

Suggest why monkeys rather than other laboratory animals, such as rats, were used for this work and comment on whether their use in this way is justified or not.							[3]

(e) The ‘fight or flight’ response to threatening environmental stimuli is coordinated by the nervous and endocrine systems.

Describe and explain how the activation of the ‘fight or flight’ response affects voluntary, involuntary and cardiac muscle.

[9]

[Total: 24]

Question: 2

Fig. 5.1 is a drawing of the brain that shows the origin of the cranial nerves.

(a) State the direction from which the brain has been drawn.

[1]
(b) (i) Name the structures A, B, C and D shown on Fig. 5.1.

A

_____________________________________________________________________________________________________

B

_____________________________________________________________________________________________________

C

_____________________________________________________________________________________________________

D

_____________________________________________________________________________________

[4]
(ii) State two roles of structure D.

1

2

[2]

(c) The hypothalamus constantly monitors and regulates the concentration of hormones in the blood. Outline how the hypothalamus regulates the concentration of hormones in the blood.

[2]
[Total: 9]

Question: 3

Fig. 2.1 is a diagram showing a section through the human brain.

(a) Use Fig. 2.1 to identify a part of the brain, A, B, C, D, or E, that is responsible for:

(i) co-ordination of the autonomic control of heart rate

[1]

(ii) co-ordination of osmoregulation by the kidney

[1]

(iii) co-ordination of the muscles involved in walking in an adult

[1]

(iv) co-ordination of the muscles required to bend the elbow joint deliberately

[1]

Fig. 2.2 shows the components of the human elbow joint.

(b) Describe how three named components of the elbow joint interact to bring about hinge movement (bending of the arm).

[3]

(c) Outline the organisation and roles of the autonomic nervous system in mammals.

In your answer you should discuss the differences in physical arrangement and the differences in function, of both parts of the autonomic nervous system.

[8] [Total: 15]

Question: 4

Fig. 4.1 shows a junction between two neurones where the neurotransmitter is dopamine.

Fig. 4.2 shows a neuromuscular junction.

(a) Complete Table 4.1 below to compare the structure and function of the dopamine synapse and the neuromuscular junction.

Table 4.1

	similarity
	difference
	
structure
			
function

[4]

(b) The sequence of events at a dopamine synapse is given below:

• dopamine molecules bind to the protein receptors on the postsynaptic membrane and trigger a response

• dopamine leaves the receptors and moves back into the presynaptic neurone

• some dopamine is repackaged into vesicles

• some dopamine is broken down by the enzyme monoamine oxidase (MAO).

Table 4.2 summarises the action of some drugs that affect dopamine synapses.

(i) Use the information in Table 4.2 to suggest which drug molecule could have a shape that differs from that of the dopamine molecule. Give a reason for your answer.

[2]

(ii) Schizophrenia is a condition in which there is a higher than usual level of dopamine in certain areas of the brain.

Suggest why phenothiazine is used to treat schizophrenia.

[2]

(c) DRD4 is a dopamine receptor in humans. The DRD4 receptor gene has a large number of alleles, of which a single individual can only have two.

(i) Explain why one individual can only have two of the different alleles of the DRD4 gene.

[2]
(ii) Name a technique that would reveal differences in the lengths of the different forms of the DRD4 receptor gene.

[1]

(d) Three alleles of DRD4 have the following alterations:

• a single base-pair substitution

• a 21 base-pair deletion

• a 13 base-pair deletion.

Suggest which of the three mutations will have the most serious consequences for the structure of the protein receptor. Give a reason for your choice.

[3]

(e) One allele of DRD4 has been found more frequently amongst individuals whose personality is described as ‘novelty-seeking’ and whose behaviour tends to be exploratory and impulsive.

Suggest how this particular allele of the DRD4 receptor could have become common in the human population.

[4] [Total: 18]

Question: 5

Fig. 2.1 is an electron micrograph showing a longitudinal section of contracted striated muscle.

(a) (i) Using Fig. 2.1, identify T, U and V.

T

U

V

[3]

(ii) Using Fig. 2.1, name the structure between positions X and Y.

[1]

(iii) Explain why glycogen granules are present in striated muscle.

[2]
(iv) Calculate the actual distance between positions X and Y on Fig. 2.1.

Show your working. Give your answer to the nearest 0.1 of a micrometre (μm).

Answer = .................................................. μm

[2]
(b) Fig. 2.2 below shows the arrangement of thick and thin filaments in striated muscle.

State what happens to the lengths of the following when muscle contracts:

A band

H zone

I band

[3]
(c) During strenuous exercise, the concentration of hydrogen ions in muscle tissue increases. A high concentration of hydrogen ions reduces the ability of calcium ions to bind to proteins in the myofibrils. This reduces the force with which a muscle can contract.

Use this information and your own knowledge of the proteins in muscle cells to explain how an increased concentration of hydrogen ions leads to a reduction in the force of contraction of a muscle.

[6] [Total: 17]