1

1. The diagram shows the structure of a synapse.

Presynapticimpulse

Presynapticmembrane

Postsynapticimpulse

Postsynapticmembrane

Mitochondrion

Synaptic vesicles

(a) Describe what would happen in the presynaptic neurone as a result of the arrival of an

action potential.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

2

(b) The graphs below show the changes in membrane potential in the presynaptic neurone

and the postsynaptic neurone as an impulse passes across a synapse.

+40

+20

0

20

40

60

80

1 2 3 4 5 6Time/ms

Membranepotential/mV

Presynapticneurone

+40

+20

0

20

40

60

80

1 2 3 4 5 6Time/ms

Membranepotential/mV

Postsynapticneurone

(i) On the graph for the postsynaptic neurone, indicate by using a letter S the point at

which the sodium channels open, allowing an increased flow of sodium ions into

the neurone. (1)

(ii) On the graph for the postsynaptic neurone, indicate by using a letter P the point at

which the potassium channels open, allowing an increased flow of potassium ions

out of the neurone. (1)

3

(iii) Calculate the delay between the arrival of the action potential at the presynaptic

neurone and the production of an action potential in the postsynaptic neurone.

Show your working.

Answer .............................................................. (2)

(iv) Explain the reason for this delay.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 9 marks)

4

2. In mammals, control of the rate of ventilation ensures that body cells have an adequate supply

of oxygen. The diagram summarises the influence of carbon dioxide concentration in the blood

upon ventilation rate.

Increasedetected

Increase inventilation rate

Optimum concentration of COin the blood

Decreasedetected

Decrease inventilation rate

Increase in COin the blood

Increase in COin the blood

Decrease in COin the blood

Decrease in COin the blood

2

2

2

2

2

(a) Give the term used to describe a control mechanism such as the one shown in the

diagram.

.................................................................................................................................... (1)

(b) (i) Name the type of receptor which detects an increase or decrease in the

concentration of carbon dioxide in the blood.

.......................................................................................................................... (1)

(ii) Name two places in the body where these receptors are located.

1 .......................................................................................................................

2 ....................................................................................................................... (2)

5

(c) Identify one physiological factor, other than a change in blood CO2 concentration, which

would cause an increase in the rate of ventilation.

.................................................................................................................................... (1)

(d) Give one physiological effect, other than an increase in ventilation rate, that is caused by

an increase in the concentration of carbon dioxide in the blood.

....................................................................................................................................

.................................................................................................................................... (1)

(Total 6 marks)

3. The diagram below shows a section through a human brain.

A

B

C

6

Complete the table below by writing in the letter and the name of the region of the brain that

carries out each function.

Function Letter Name of region

Initiating and controlling

voluntary muscle

movement

Coordinating skeletal

muscle movement, balance

and posture

Controlling heart and

breathing rate

(Total 4 marks)

4. The diagram shows a longitudinal section through part of the axon of a myelinated neurone.

Myelinsheath

(a) Describe the structure of the myelin sheath.

.

.

.

. (2)

7

(b) The table shows the speed of conduction of an impulse along axons with different

diameters. Data from both myelinated and non-myelinated neurones are included.

Type of neurone Diameter of axon

/m

Speed of conduction

/m s1

Non-myelinated

Non-myelinated

Non-myelinated

Myelinated

Myelinated

2

15

700

10

15

2

5

22

30

80

With reference to the data, describe and explain the effect that the myelin sheath has on

the speed of conduction of a nerve impulse.

.

.

.

.

.

.

.

.

.

. (5)

(Total 7 marks)

5. Give an account of the role of pigments in the detection of light by flowering plants

and animals.

(Allow three lined pages) (Total 10 marks)

8

6. In an investigation into the effect of a drug on the nervous system, the reaction time of four

volunteers was tested by timing how long it took for them to push a button after seeing a

lamp light up.

Volunteer A drank 50 cm3 of water. Volunteers B, C and D each drank 50 em of a solution containing different concentrations of the drug. The reaction time of each volunteer was then

tested every ten minutes during the next hour.

Volunteer

A

B

C

D

0

1

2

3

0 min

0.3

0.3

0.2

0.3

10 min

0.3

0.4

0.5

0.8

20 min

0.2

0.4

0.6

0.9

30 min

0.2

0.4

0.6

1.0

40 min

0.2

0.3

0.5

1.0

50 min

0.2

0.2

0.4

0.9

60 min

0.2

0.3

0.4

0.9

Concentrationof drug/

arbitrary units

Reaction time / seconds

(a) Suggest what the data indicate about the absorption of the drug into the bloodstream.

Give a reason for your answer.

.

.

.

. (2)

(b) Describe the effects that the drug had upon the reaction times of the volunteers during

the 60 minutes of the investigation.

.

.

.

.

.

. (3)

9

(c) This drug is known to affect synaptic transmission. Suggest how the drug might cause the

effects you have described in (b).

.

.

.

.

.

. (3)

(d) Give three factors, other than the concentration of the drug, that would need to be

taken into account in this investigation.

1 .

2 .

3 . (3)

(Total 11 marks)

7. Multiple sclerosis is a disease of the nervous system in which the myelin sheath around the

neurones of the central nervous system is damaged. The symptoms of multiple sclerosis are

wide ranging, including loss of limb control, tiredness, speech impairment and eye problems.

The exact cause of the disease is unknown, but it appears to involve the bodys immune system attacking the myelin. The myelin is made up of many cell membranes packed closely together,

and so consists mostly of lipids and proteins. In multiple sclerosis, it is destroyed and replaced

by scar tissue.

Describe the role of the myelin sheath and suggest how damage to the myelin sheath could

interfere with the transmission of nerve impulses.

(Allow one lined page) (Total 6 marks)

10

8. The diagram below shows the neurones involved in a spinal reflex arc.

Receptor

Effector

Sensory neurone

Effector (motor) neurone

Synaptic cleft

Neurone X

Portion ofspinal cord

(a) Name neurone X.

............................................................................................................................... (1)

(b) Explain the significance of this neurone in a reflex arc.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

............................................................................................................................... (2)

11

(c) Describe how an action potential is produced in the effector neurone, following the

diffusion of transmitter substance across the synaptic cleft.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

............................................................................................................................... (4)

(Total 7 marks)

9. The diagram below represents a section through the human retina.

Cone cell

Rod cell

Bipolar cell

Ganglion cell

To brain

12

(a) Name the retinal pigment found in a rod cell.

............................................................................................................................................ (1)

(b) Explain how the pigment in rod cells is involved in the conversion of light energy into

nerve impulses.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................ (4)

(c) Using the information in the diagram, suggest why stimulation of cone cells results in a

more detailed image than stimulation of rod cells.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................ (3)

13

(d) The eye of a species of moth contains three different pigments. The table below shows

the wavelengths and colours of light which are most strongly absorbed by these pigments.

Pigment Wavelength most strongly absorbed/nm

A 350 (ultraviolet)

B 440 (violet)

C 525 (green)

Using information in the table, and your knowledge of the retinal pigments in the human

eye, compare the sensitivity to colour of the moth's eye with that of the human eye.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................ (3)

(Total 11 marks)

10. Give an account of the sequence of events by which the arrival of an action potential at a

synapse results in an action potential in the post-synaptic neurone.

(Allow two lined pages) (Total 8 marks)

14

11. The diagram below shows a transverse section of the spinal cord of a mammal.

A

B

C

Whitematter

(a) Name the parts labelled A, B, and C.

A .........................................................................................................................................

B .........................................................................................................................................

C ......................................................................................................................................... (2)

15

(b) The white matter in the spinal cord is mainly composed of the myelinated axons of

neurones. The graph below shows the conduction velocity of myelinated and non-

myelinated neurones.

8

6

4

2

00 1 2 3 4

Axon diameter / m

Conduction velocity / m s1

Myelinated

Non-myelinated

(i) Compare the conduction velocities of myelinated and non-myelinated neurones.

(3)

16

(ii) Explain the role of myelin in nerve impulse transmission.

(2)

(c) Explain how simple reflexes are important in the responses of mammals to changes in the

external environment.

(2)

(Total 9 marks)

12. The data below show some of the changes that occur in the cardiovascular system as a result of

different levels of exercise.

Level of exercise

At rest Light Medium Intense

Heart rate

/beats min1

72 144 160 190

Cardiac output

/dm3 min

1

5 13 16 21

17

(a) Using the data from the table, calculate the stroke volume when exercising at an intense

level. Show your working.

Answer ......................................... (2)

(b) The graph below shows typical blood pressures at different levels of exercise.

Blood pressure / mm Hg

200

150

100

50

0At rest Light Medium Intense

Level of exercise

Systolicpressure

Diastolicpressure

(i) Explain what is meant by the term blood pressure.

(1)

18

(ii) With reference to the graph, describe the effect of exercise on blood pressure.

(3)

(iii) Using the data in the table and the graph, suggest why the systolic pressure rises

with increasing level of exercise.

(2)

(c) State two sites in the body where blood pressure receptors are found.

1 .........................................................................................................................................

2 ......................................................................................................................................... (2)

(Total 10 marks)

19

13. Parkinsons disease leads to the gradual loss of balance and movement, often with muscle tremors. This disease is believed to be caused by a lack of the neurotransmitter dopamine in

parts of the brain. The disease can be treated with the drug L-dopa.

(a) Explain why the lack of dopamine leads to the symptoms of Parkinsons disease.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(b) Suggest why L-dopa, rather than dopamine, is used for the treatment of patients with

Parkinsons disease.

.....................................................................................................................................

..................................................................................................................................... (1)

(c) Multiple sclerosis is a disease that causes patches of inflammation in the brain. State the

name of an imaging technique and describe how the images could be used to establish

which parts of the brain have been damaged in a patient with multiple sclerosis.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 6 marks)

20

14. There is much debate about the reasons for variation in human characteristics. One source of

evidence in this nature and nurture debate is provided by studies of identical (monozygotic or MZ) twins.

In one study, which involved 69 pairs of identical twins, fifty pairs of the twins had been

brought up together since birth and nineteen pairs of the twins had been brought up apart since

birth. The height, body mass and intelligence (IQ) of each twin was measured and the difference

between each pair was determined for each characteristic.

The table below shows the mean differences between the pairs of twins.

Mean difference

Characteristic 50 pairs of identical twins

brought up together

19 pairs of identical twins

brought up apart

Height/cm 1.7 1.8

Body mass/kg 1.9 4.5

Intelligence (IQ) 3.1 6.0

(a) Explain what these figures suggest about the effects of nature and nurture on these three

characteristics.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

21

(b) Suggest two reasons why the conclusions drawn from the data above should be treated

with caution.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

15. (a) Explain how nerve impulses are conducted along a myelinated axon after an action

potential has been initiated. You should write your answer in continuous prose.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (6)

22

(b) Habituation is a type of learning that allows animals to ignore repeated unimportant

stimuli. For example, snails withdraw their tentacles when the tentacles are gently

touched, but if the tentacles are repeatedly stimulated in this way they are no longer

withdrawn.

23

The diagram below shows a synapse involved in this type of response.

Ca2+Calciumchannel

Neurone 1 Neurone 2

With repeated stimulation the calcium channels become less responsive. Using the

diagram of the synapse and your own knowledge, suggest how changes in the functioning

of the synapse might bring about habituation.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 10 marks)

24

16. The table below refers to some regions of the brain and their functions. Complete the table by

inserting the correct word or words.

Region of brain One function

Medulla

Learning and memory

Control of balance and fine movement

Hypothalamus

(Total 4 marks)

17. Neurones transmit electrical impulses along their cell surface membranes when stimulated to do

so. These impulses are called action potentials and involve changes in the electrical potential

across the membranes due to movement of positive ions.

The diagram below shows the distribution of charge inside and outside an unmyelinated axon as

an impulse passes along.

+ + + + + +

+ + + + + +

+ + + + + + + + + + + + + + + + + + + + + +

+ + + + + + + + + + + + + + + + + + + + + +

D C B A

Axon

Direction of impulse

25

(a) Use the most suitable term from the list below to describe the state of the axon in regions

B, C and D. Region A has been done for you.

Depolarising Resting Repolarising

A Resting

B ......................................................................

C ......................................................................

D ...................................................................... (2)

(b) The diagram below shows two action potentials recorded using an oscilloscope.

Membrane

potential

/mV

+60

+40

+20

0

20

40

60

80

1000 1 2 3 4 5 6 7 8 9

X

Time/ m s

26

(i) Explain how the change in membrane potential between 0.5 and 2.0 milliseconds is

brought about.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

............................................................................................................................... (4)

(ii) Calculate the number of action potentials occurring per second. Show your

working.

Answer .................................. per second (2)

(c) Explain what is taking place during the period marked X on the diagram in part (b).

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (3)

(Total 11 marks)

27

18. Give an account of the detection of light by pigments in the mammalian eye.

(Allow two lined pages) (Total 9 marks)

19. (a) The table below compares three features of nervous and hormonal coordination.

Complete the table to show the differences between the two types of coordination.

Feature Nervous coordination Hormonal coordination

Method of transmission

Speed of transmission

Duration of the response

(3)

(b) Give one similarity between the methods of transmission involved in nervous and

hormonal coordination.

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

....................................................................................................................................... (1)

(Total 4 marks)

20. Give an account of the location and functions of each of the following areas of the mammalian

brain: cerebral hemispheres, cerebellum and medulla.

(Allow two lined pages) (Total 10 marks)

28

21. The diagram below illustrates some aspects of the regulation of heart rate.

(a) Complete the flow diagram by naming the part of the heart that receives impulses from

the two nerves (1)

(b) Strenuous physical activity will increase the volume of blood flowing through the venae

cavae and into the right atrium. This will trigger a reflex action.

(i) Name the reflex that will be initiated.

............................................................................................................................... (1)

29

(ii) Using your own knowledge and the information provided, explain how this

increase in blood volume in the venae cavae and right atrium causes a change in

heart rate.

................................................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................ (3)

(c) The coordination of the heart beat is disrupted when the conducting systems of the heart

are damaged. This type of disease is called heart block. Describe how an artificial

pacemaker can be used to treat this condition.

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

.......................................................................................................................................

....................................................................................................................................... (3)

(Total 8 marks)

30

22. The diagram below shows a vertical section through a human brain.

A

B

C

D

E

(a) Using the letters A, B, C, D or E, state which region of the brain:

(i) coordinates movement

........................................................................................................................... (1)

(ii) controls heart rate

........................................................................................................................... (1)

(iii) receives sensory input from the eyes.

........................................................................................................................... (1)

31

(b) Researchers covered one eye of a new born kitten. Three months later, when the eye was

uncovered, the kitten remained blind in that eye. Covering the eye of an adult cat for three

months did not blind it. Explain what these results show about how vision develops in

cats.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

23. The graph below shows the effect of light intensity on the area of the pupil in the human eye.

5

4

3

2

1

00 1 2 3 4 5 6 7 8

Pupil area/ mm 2

Light intensity / arbitrary units

(a) (i) Describe the effect of changing light intensity on the area of the pupil.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (1)

32

(ii) Explain how the muscles in the eye bring about this change.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(b) Change in area of the pupil is controlled by a reflex action. In this pupil reflex, name

(i) the receptor

...........................................................................................................................

the effector

........................................................................................................................... (1)

(ii) Explain why the pupil reflex still occurs in an unconscious person.

...........................................................................................................................

........................................................................................................................... (1)

(c) Atropine is used to dilate the pupil to allow the eye to be examined more easily.

Atropine inhibits the activity of acetylcholine. Suggest how atropine causes this

inhibition.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

33

(d) The diagram shows a light sensitive cell from the eye. The activity of the cell in the dark

is shown.

Rhodopsin pigment

Sodium

(Na+ ) ions

Outer

segment

Inner

segment

Neurotransmitter released

Bipolar cell inhibited

Synapse

Dark

Using the above diagram and your own knowledge, explain how light causes the

depolarisation of the bipolar cell.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (5)

(Total 12 marks)

34

24. (a) The graph below shows the changes in membrane potential of a myelinated nerve

fibre when a nerve impulse travels along it. The maximum depolarisation in the nerve

fibre is +40 mV.

1 2 3 4 5 6

Time / ms

+40

+20

0

20

40

60

80

Mem

bra

ne

po

tenti

al /

mV

(i) On the graph, draw an arrow to show the time when the sodium ion channels open. (1)

35

(ii) Explain the meaning of the term myelinated.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(iii) State what effect myelination has on the speed of conduction.

...........................................................................................................................

........................................................................................................................... (1)

36

(b) On the graph below show the changes in membrane potential of a nerve fibre, with a

resting potential of 60mV and a maximum depolarisation of +35mV, during the passage of an impulse.

1 2 3 4 5 6

Time / ms

+40

+20

0

20

40

60

80

Mem

bra

ne

po

tenti

al /

mV

(2)

(Total 6 marks)

37

25. Nerve impulses travel across a synapse from a sensory neurone to a relay neurone in the spinal

cord.

Describe how a nerve impulse is transmitted across a synapse.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

............................................................................................................................................... (Total 6 marks)

38

26. The diagram below shows one type of mammalian neurone.

Dendrite

Cell body

Node of Ranvier

Synaptic knob

39

(a) (i) Name the type and state the role of the neurone shown in the diagram.

Type: ................................................................................................................

Role: .................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

40

(ii) Draw an arrow on the diagram to show the direction in which an impulse would

travel. (1)

41

(b) State precisely where in the central nervous system the cell body of this type of neurone

is found and explain the importance of the dendrites.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

42

(c) Describe the node of Ranvier and explain its importance in the neurone.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 8 marks)

43

27. The human brain has many different neurotransmitters which influence behaviour. One of these

neurotransmitters is serotonin. A lack of serotonin in the brain can cause depression and an

excess can cause anxiety. Drugs that increase levels of serotonin are used as antidepressants.

The diagram below shows a synapse in which serotonin acts as a neurotransmitter.

Vesicle containing

serotonin

Serotonin

synthesis

postsynaptic

membrane

presynaptic

membrane

synaptic

cleft

Key

Serotonin postsynaptic receptor

Serotonin re-uptake mechanism

Serotonin

(a) In sufferers of depression the levels of serotonin are reduced. Using the diagram above,

suggest one explanation for low serotonin levels.

.....................................................................................................................................

..................................................................................................................................... (1)

44

(b) Use the diagram and your own knowledge of synaptic transmission to explain how

information is transmitted across a synapse.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (6)

(c) Using the information given, suggest and explain two ways antidepressants work.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

45

(d) The drug known as ecstasy (MDMA) can cause anxiety. The diagram below represents an

ecstasy molecule. Using your knowledge and the diagrams provided suggest how ecstasy

may have this effect.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 12 marks)

28. The diagram below shows a vertical section through a human brain.

(a) On the diagram, draw an arrow to show the position of the hypothalamus. (1)

46

(b) The forebrain, midbrain and hindbrain are the three main regions of the human brain.

State in which region of the brain the hypothalamus is found.

..................................................................................................................................... (1)

(c) Give two functions of the hypothalamus.

1 ..................................................................................................................................

.....................................................................................................................................

2 ..................................................................................................................................

..................................................................................................................................... (2)

(Total 4 marks)

29. The diagram below shows a section through part of a mammalian retina.

A

D

B

C

(a) (i) State which of the parts labelled A, B, C or D, contains iodopsin.

........................... (1)

47

(ii) There are three different forms of iodopsin. State how many different forms of

iodopsin would be present in the cells shown in the diagram.

........................................................................................................................... (1)

(b) Explain how rhodopsin is involved in the conversion of light energy into electrical

energy.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 6 marks)

30. Give an account of how a nerve impulse is generated in a post-synaptic neurone following the

release of a neurotransmitter.

(Allow two lined pages). (Total 10 marks)

48

31. (a) Pavlov carried out experiments on dogs to investigate classical conditioning.

Explain how the dogs became conditioned to salivate at the sound of a bell in Pavlovs experiments.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(b) Using operant conditioning, pigeons were presented with coloured keys and taught to

peck one particular key. Suggest how this operant conditioning was achieved.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

49

(c) Briefly discuss the extent to which the study of learning in animals can help us to

understand learning in humans.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(d) Explain how functional magnetic resonance imaging (fMRI) can improve our knowledge

of human brain function.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 9 marks)

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32. The picture below shows the response of a cats pupil to bright light.

(a) (i) Describe how the nervous system controls the pupil reflex in a mammal such as a

cat, in response to bright light.

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(ii) Describe and explain how myelination of neurones is an advantage in this reflex

pathway.

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(b) Hubel and Weisel covered one eye of kittens of different ages to investigate the timing of

visual development in mammals.

Kittens which had one eye covered from the fourth to the fifth week subsequently had

very poor vision in that eye. Kittens which had one eye covered at earlier or later times

had normal vision. Suggest an explanation for these observations.

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(c) Some people have ethical objections to animal experiments. Suggest how a biologist

might justify the use of animals in experiments.

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(Total 12 marks)

33. The diagram below shows a human brain seen from the side.

(a) Name the parts labelled B and C.

B ..................................................................................................................................

C .................................................................................................................................. (2)

(b) Give two functions of the part labelled A.

1 ..................................................................................................................................

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2 ..................................................................................................................................

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(Total 4 marks)

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34. State three ways in which hormonal control differs from nervous control.

1 ............................................................................................................................................

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3 ............................................................................................................................................

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35. (a) When an action potential arrives at a synaptic knob, acetylcholine is released.

Describe how acetylcholine is released into the synaptic cleft.

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(b) The graph below shows a recording of an action potential produced after the binding of

acetylcholine to receptors on a post-synaptic membrane.

+35

0

35

70

43210

Time / ms

Membranepotential / mV

(i) Use the graph to state the time at which the sodium channels open to allow an

increased flow of sodium ions into the neurone.

.................................................... ms (1)

(ii) Use the graph to state the time at which the hyperpolarisation is at its greatest.

.................................................... ms (1)

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(iii) Calculate the number of action potentials that could occur in one second if the

stimulus is maintained. Show your working.

Answer ....................................... action potentials per second. (2)

(c) When a transmitter substance called gamma-aminobutyric acid (GABA) is released at a

synapse, it causes chloride ion (Cl) channels and potassium ion (K+) channels to open in the post-synaptic membrane. This results in chloride ions moving into the post-synaptic

neurone and potassium ions moving out.

Explain why an action potential is less likely to develop when GABA is released at the

same time as acetylcholine.

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(Total 9 marks)

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36. Detection of light occurs in both mammals and flowering plants.

(a) In humans, the central region of the retina has very few rod cells. However, in a dog

about 8090% of the photoreceptors in the central region of the retina are rod cells. Suggest one advantage to a dog of having more rod cells in this region of the retina.

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(b) Humans have three types of cone cell. However, dogs only have two types of cone cell.

Graph 1 below shows the percentage of light, of different wavelengths, absorbed by the

pigments in the two types of cone cell in a dogs retina. Graph 2 shows the percentage of light, of different wavelengths, absorbed by the

pigments in the three types of cone cell in a humans retina.

100

75

50

25

0

400 450 500 550 600 650 700

Wavelength of light /nm

Percentage

of light

absorbed (%)

Graph 1

100

75

50

25

0

400 450 500 550 600 650 700

Wavelength of light /nm

Percentage

of light

absorbed (%)

Graph 2

Wavelength/nm Colour

400 Violet

475 Blue

510 Green

570 Yellow

590 Orange

650 Red

Table 1

Three balls, that differed only in their colour, were placed in front of a dog and a human.

One ball was red, one yellow and one orange. Using this data, explain why only the

human would be able to detect a difference between the colour of the three balls.

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(c) Describe the detection of light in flowering plants.

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(Total 8 marks)

37. Give an account of the structure and functions of sensory, relay and effector (motor) neurones.

(Allow two lined pages). (Total 10 marks)

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38. The diagram below shows a rod cell from the retina of the human eye.

End bulb

Inner

segment

Outer

segment

Connecting pair

of cilia

Vesicles

(containing

photosensitive

pigments)

Mitochondrion

Nucleus

The function of rod cells can be affected by the condition known as retinitis pigmentosa.

Retinitis pigmentosa causes the gradual breakdown of photoreceptor cells in the retina. As these

cells degenerate and die, patients experience progressive loss of vision.

One of the most common forms of retinitis pigmentosa can be caused by a recessive allele

inherited from parents who have normal vision.

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With reference to the function of rod cells and rhodopsin as photoreceptors, explain why people

with retinitis pigmentosa experience progressive loss of vision.

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39. Research on visual development in cats has led to knowledge of how information is processed

in the visual cortex of the brain. The diagrams below show the growth of neurones in part of the

visual cortex after normal visual development and when the left eye has been deprived of

sensory information.

Normal Visual Development Sensory Deprivation in the

Left Eye

Left

eye

Right

eye

Closed

left eye

Right

eye

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(a) Use the diagrams above to describe differences in the visual cortex after sensory

deprivation.

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(b) Explain how this type of experiment has provided evidence which shows the need for

exposure to sensory information in normal visual development.

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(c) Describe one other piece of evidence which suggests that humans must be exposed to

particular stimuli if they are to develop normal vision.

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(Total 5 marks)

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40. People with Parkinsons disease have poor control over their skeletal muscles, caused by a lack of the neurotransmitter dopamine. Large numbers of neurones secreting dopamine are found in

the basal ganglia region of the brain.

Parkinsons disease can be diagnosed and monitored using brain scans. The fMRI scans below show the results of a study where subjects did a standard finger-tapping activity to investigate

the effectiveness of a new drug treatment.

The results below are from a healthy brain, a patient with Parkinsons disease without drug treatment and a patient with Parkinsons disease taking drug treatment. The scan shows a horizontal section with the front of the head at the top. The most active areas are white.

(a) Using the fMRI scans above, discuss the effects of this new drug on brain activity.

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(b) Explain how neurotransmitters, such as dopamine, stimulate neurones.

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(c) People with Parkinsons disease have much less dopamine in their brain than other people. Using the information already given in this question and your own knowledge,

suggest and explain how Parkinsons disease can be treated using drugs.

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(Total 11 marks)

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41. Answer the following essay question.

You are expected to answer in continuous prose. You should use examples from the biology

course you have studied but need not restrict yourself to the course content.

You are advised to spend approximately 45 minutes answering Question 3 or Question 4,

including planning time.

Marks will be awarded in the following areas:

Breadth: selecting a range of aspects of biology from different parts of your AS and A2 course

which are relevant to the question. (up to 6 marks)

Depth: developing the aspects you have chosen by including relevant details, examples and

discussion. (up to 8 marks)

Balance: have you answered the question asked? for example, by dealing with the bigger ideas

which lie beneath the wor