The brain, the eye and control of body temperature – GCSE Biology exam questions with mark scheme

1Grade 1–3FoundationTriple only6 marks

The diagram shows a side view of the human brain.

(a) Name the parts of the brain labelled P, Q and R. [3]

(b) Which part, P, Q or R, controls unconscious activities such as the heartbeat and breathing rate? [1]

Suggest which part of the brain, P, Q or R, the alcohol is affecting. [1]

(d) The brain is made of billions of interconnected cells. Name this type of cell. [1]

P: cerebral cortex (allow cerebrum / cerebral hemisphere)(1)
Q: cerebellum (do not accept cerebrum)(1)
R: medulla (allow medulla oblongata; allow brain stem)(1)
R (allow medulla if letter not given but name is correct)(1)
Q (allow cerebellum)(1)
neurones (allow neurons / nerve cells)(1)
Answer: (a) P cerebral cortex, Q cerebellum, R medulla; (b) R; (c) Q; (d) neurones.
Examiner tip: Cerebellum and cerebrum sound alike — the cerebellum is the small, ridged part at the back, under the cerebral cortex, and it controls balance and coordination.

2Grade 1–3FoundationTriple only6 marks

The diagram shows a section through a human eye.

(a) Name the structures labelled A, C and F. [3]

(b) Give the letter of the structure that contains the receptor cells that are sensitive to light. [1]

(d) What is the function of structure B? [1]

A: cornea(1)
C: ciliary muscle (allow ciliary body; do not accept suspensory ligament)(1)
F: sclera (ignore 'white of the eye' on its own)(1)
D(1)
(optic nerve) carries (nerve) impulses from the retina / eye to the brain (allow sends signals / messages to the brain; do not accept carries light to the brain)(1)
(iris) controls the size of the pupil / controls how much light enters the eye(1)
Answer: (a) A cornea, C ciliary muscle, F sclera; (b) D (retina); (c) carries impulses from the retina to the brain; (d) controls pupil size, so controls the amount of light entering the eye.
Examiner tip: The optic nerve carries electrical impulses, not light — answers that say it 'takes light to the brain' get no mark.

3Grade 4–5Triple only5 marks

Amira reads a text message on her phone. She then looks up at an aeroplane high in the sky.

Her eye changes so that the image stays focused on the retina.

(a) Copy and complete the table to show what happens in Amira's eye when she looks at each object.

	Looking at the phone (near)	Looking at the aeroplane (distant)
Ciliary muscles
Suspensory ligaments
Shape of the lens
How strongly the lens refracts light

[4]

(b) Give the name of the process that changes the shape of the lens to focus on near or distant objects. [1]

ciliary muscles: contract (near) and relax (distant) — both needed for the mark(1)
suspensory ligaments: loosen / slacken (near) and are pulled tight / tighten / taut (distant)(1)
lens: thicker / fatter / more curved / more rounded (near) and thinner / flatter / pulled thin (distant)(1)
refraction: more strongly (near) and less strongly / only slightly (distant) (allow 'more' and 'less'; ignore 'bends light' without comparison)(1)
accommodation(1)
Answer: Near: ciliary muscles contract, suspensory ligaments slacken, lens thicker, refracts light more strongly. Distant: ciliary muscles relax, ligaments pulled tight, lens thin/flat, refracts light less strongly. (b) Accommodation.
Examiner tip: The commonest error is to think the ligaments tighten when the muscles contract — for a NEAR object the muscles contract and the ligaments go SLACK, letting the lens spring thicker.

4Grade 6–7Triple only6 marks

The diagrams show how light from a distant object is focused in the eyes of two people, X and Y. Neither person has normal vision.

(a) Which person, X or Y, is short-sighted (has myopia)? Give a reason for your answer using the diagrams. [2]

(b) Suggest one cause of the problem in eye X. [1]

(d) Person Y is considering laser eye surgery instead of wearing spectacles.

Give one advantage and one disadvantage of laser surgery compared with wearing spectacles. [2]

X(1)
(light from a distant object) is focused / the rays meet in front of the retina (allow image formed before the retina) (dependent on X)(1)
eyeball is too long or lens is too thick / too curved / refracts light too strongly (allow cornea too curved; ignore 'lens is faulty')(1)
convex lens (allow converging lens)(1)
advantage: permanent / long-term correction or no need to wear / remember / buy / replace spectacles or not affected by sport / weather (any one)(1)
disadvantage: risk of complications / infection / damage to eye / surgery may go wrong or expensive (at once) / not suitable for everyone / cannot be reversed (any one)(1)
Answer: (a) X — light is focused in front of the retina. (b) Eyeball too long or lens too thick / refracts too strongly. (c) Convex (converging) lens. (d) e.g. advantage: permanent, no glasses needed; disadvantage: risk of damage / infection, expensive.
Examiner tip: Say WHERE the light is focused relative to the retina ('in front of' or 'behind') — 'the image is blurry' does not explain which defect it is.

5Grade 4–5Triple only7 marks

A scientist measured the volume of blood flowing to the skin of a volunteer's hand at different air temperatures. The volunteer's core body temperature stayed at 37 °C throughout.

The graph shows the results.

(a) Describe the pattern shown by the graph. [2]

(b) Calculate the percentage increase in blood flow to the skin when the air temperature rises from 20 °C to 35 °C. [2]

(c) Explain how the change in blood flow at 35 °C helps to stop the volunteer's core body temperature from rising. [2]

(d) Name the part of the body that monitors the temperature of the blood. [1]

as air temperature increases, blood flow to the skin increases (allow positive correlation)(1)
increases slowly at first then more rapidly / steeply (above 20–25 °C) or correct use of data with units, e.g. 2 cm³ per min at 10 °C rising to 32 cm³ per min at 35 °C(1)
(32 − 5) ÷ 5 (× 100) (allow 27 ÷ 5)(1)
540 (%) (correct answer scores 2 marks)(1)
(vasodilation so) more blood flows (through capillaries) near the skin surface(1)
so more energy / heat is transferred / lost from the skin to the surroundings (by radiation) (do not accept 'heat is released' without reference to loss to surroundings)(1)
thermoregulatory centre in the brain (allow hypothalamus; do not accept 'brain' alone)(1)
Answer: (a) Blood flow increases as air temperature increases, slowly at first then more steeply. (b) 540%. (c) More blood near the skin surface, so more heat lost to the surroundings by radiation. (d) Thermoregulatory centre (in the brain).
Examiner tip: For percentage change always divide by the ORIGINAL value (5, not 32) — dividing by 32 gives 84%, which scores zero.

6Grade 6–7HigherTriple only6 marks

A marathon runner is racing on a hot day. Her muscles are respiring rapidly and her core body temperature starts to rise above 37 °C.

Explain how the runner's body detects the rise in temperature and how the responses of her body bring her temperature back down towards 37 °C. [6]

respiration in the muscles releases energy, some as heat, so the blood temperature rises(1)
temperature receptors in the skin detect the change and send (nerve) impulses to the thermoregulatory centre(1)
the thermoregulatory centre (in the brain) has receptors that monitor the temperature of the blood (flowing through it)(1)
the thermoregulatory centre sends impulses to effectors (sweat glands and blood vessels in the skin)(1)
vasodilation: blood vessels / arterioles supplying the skin capillaries dilate (widen)(1)
so more blood flows close to the skin surface(1)
more energy is transferred from the blood to the surroundings by radiation(1)
sweat glands produce more sweat(1)
water in sweat evaporates from the skin, which transfers energy away from the skin / cools the skin(1)
this is negative feedback: once temperature returns to normal the responses are reduced(1)

Level	Marks	What it looks like
Level 3	5–6	Detection is explained (skin receptors and the thermoregulatory centre monitoring blood temperature) and BOTH vasodilation and sweating are linked clearly to how they cause energy to be lost from the body. The answer forms a logical sequence from stimulus to response.
Level 2	3–4	Both responses are described, with an explanation of how at least one of them lowers body temperature, OR one response is fully explained together with how the change is detected. Some steps may be missing or out of order.
Level 1	1–2	One or more relevant statements, such as 'she sweats' or 'blood vessels get wider', with little or no explanation of how temperature is lowered or how the change is detected.
No relevant content	0	Nothing worthy of credit.

Answer: Skin temperature receptors send impulses to the thermoregulatory centre, which also monitors blood temperature. It sends impulses to effectors: blood vessels supplying skin capillaries dilate so more blood flows near the surface and more heat is radiated to the surroundings; sweat glands release more sweat, and evaporation of water from sweat transfers energy away from the skin.
Examiner tip: Examiners reject 'blood vessels move closer to the skin' — they widen (dilate) so more blood flows near the surface; and sweat only cools you when its water EVAPORATES.

7Grade 6–7HigherTriple only6 marks

An open-water swimmer enters the sea when the water temperature is 14 °C.

(a) Give the name of the part of the brain that receives impulses from temperature receptors in the swimmer's skin. [1]

(b) The swimmer's body responds to the cold by vasoconstriction.

Explain how vasoconstriction reduces the loss of heat from the swimmer's body. [3]

Explain how shivering helps to raise body temperature. [2]

thermoregulatory centre (allow hypothalamus; do not accept 'brain' alone or 'medulla')(1)
the blood vessels / arterioles (supplying the skin capillaries) become narrower (ignore capillaries constrict; do not accept vessels move away from the skin)(1)
so less blood flows through the capillaries near the skin surface(1)
so less energy / heat is transferred from the blood to the surroundings / water (by radiation / conduction) (allow more heat kept in the core of the body)(1)
muscles contract (and relax) rapidly / automatically(1)
this needs (more) respiration, which releases energy / heat (that warms the blood) (do not accept 'produces energy')(1)
Answer: (a) Thermoregulatory centre. (b) Arterioles to the skin narrow, less blood flows near the skin surface, so less heat is transferred to the surroundings. (c) Muscles contract rapidly, increasing respiration, which releases energy as heat.
Examiner tip: Never write that blood vessels 'move' away from the skin or that respiration 'produces' energy — both are standard lost marks.

8Grade 6–7HigherTriple only6 marks

Neuroscientists have mapped which regions of the brain control different functions.

(a) A patient has a stroke that damages her cerebellum.

Suggest one effect this damage is likely to have on the patient. [1]

(b) During brain surgery on a conscious patient, a surgeon used electrical stimulation to map a region of the cerebral cortex.

Describe how electrical stimulation can be used to find out the function of a region of the brain. [2]

(c) Give one advantage of using MRI scanning, rather than studying patients with brain damage, to map the brain. [1]

(d) A patient has a tumour deep inside the brain.

Explain why it is difficult to treat the tumour with surgery. [2]

poor balance / poor (muscle) coordination / clumsy / difficulty walking / unsteady movement (ignore paralysis; ignore memory loss)(1)
a (small) electric current is passed into / applied to a region of the brain (through an electrode)(1)
the response is observed, e.g. which part of the body moves / what the patient feels / says / remembers, so the region is linked to that function(1)
can be done on healthy / living people or no need to wait for brain damage to occur or non-invasive / no surgery needed or shows which regions are active during a particular task (allow 'can see inside the brain without cutting')(1)
the brain is delicate / complex / easily damaged, so it is hard to reach the tumour without damaging (other) brain tissue / neurones(1)
damaged neurones / brain tissue may not repair / regenerate, so the patient could lose functions (e.g. memory, movement, speech) (allow surgery could cause permanent disability)(1)
Answer: (a) Loss of balance / coordination. (b) Pass a small electric current into a region and observe which body part responds or what the patient experiences. (c) Can be used on healthy people / non-invasive. (d) Hard to reach the tumour without damaging other delicate brain tissue; damaged neurones may not be repaired, so functions could be lost.
Examiner tip: In (b) you must say what is OBSERVED after stimulating — just 'they stimulate the brain with electricity' only gets 1 mark.

9Grade 6–7Triple only6 marks

A student measured the diameter of the pupil of her partner's eye in a dimly lit room and then in bright light.

Lighting	Pupil diameter in mm
Dim	7.0
Bright	2.5

(a) Name the structure in the eye that changes the diameter of the pupil. [1]

(b) The amount of light entering the eye is proportional to the area of the pupil. The pupil is circular.

Calculate how many times more light enters the eye in dim light than in bright light.

Give your answer to 2 significant figures. [2]

(d) Light is detected by receptor cells in the retina.

Name the structure that carries impulses from the retina to the brain and give the part of the brain responsible for conscious vision and interpreting what we see. [2]

iris (do not accept cornea / lens / ciliary muscle)(1)
(7.0 ÷ 2.5)² or π × 3.5² ÷ (π × 1.25²) or 38.5 ÷ 4.91 (allow ratio of areas set up correctly)(1)
7.8 (correct answer to 2 s.f. scores 2 marks; 7.84 scores 1 mark; 2.8 (ratio of diameters, not areas) scores 0)(1)
prevents too much light entering / reaching the retina, which could damage the retina / light receptor cells (allow protects the retina / eye from damage by bright light)(1)
optic nerve(1)
cerebral cortex (allow cerebrum; do not accept cerebellum or medulla)(1)
Answer: (a) Iris; (b) (7.0/2.5)² = 7.84 ≈ 7.8 times; (c) stops too much light damaging the retina; (d) optic nerve; cerebral cortex.
Examiner tip: Light depends on AREA, not diameter — 7.0 ÷ 2.5 = 2.8 scores no marks; square the ratio (or use πr²) to get 7.84, then round to 7.8.

10Grade 8–9HigherTriple only7 marks

A runner was weighed before and after a 75-minute training run on a hot, dry day.

Measurement	Value
Body mass before the run in kg	68.4
Body mass after the run in kg	67.1
Volume of water drunk during the run in dm³	0.30

1 dm³ of water or sweat has a mass of 1 kg. The runner did not urinate during the run.

(a) Assume that sweating was the only way the runner's body lost mass during the run. Calculate the mass of sweat produced during the run. [2]

(b) Calculate the mean rate of sweat production in dm³ per hour. [2]

(d) The runner did the same run on a day that was equally hot but very humid.

Explain why his core body temperature rose more on the humid day. [2]

(68.4 − 67.1) + 0.30 (allow 1.3 + 0.3)(1)
1.6 (kg) (correct answer scores 2 marks; allow 1 mark for 1.3 (kg) – mass lost without adding the water drunk; 1.0 (from 1.3 − 0.3) scores 0)(1)
1.6 ÷ 1.25 or 1.6 ÷ (75 ÷ 60) (allow ecf from (a))(1)
1.28 (dm³ per hour) (allow 1.3; correct answer scores 2 marks)(1)
water vapour is lost in exhaled air / breathing (allow mass lost as carbon dioxide from respiration / glucose or fat used in respiration)(1)
(in humid air) less sweat / water evaporates from the skin (allow evaporation is slower; allow sweat drips off instead of evaporating; do not accept 'less sweat is produced')(1)
evaporation (of water in sweat) transfers energy / heat away from the skin, so less energy is lost from the body (ignore 'sweat cools the body' without reference to evaporation)(1)
Answer: (a) 1.6 kg; (b) 1.28 dm³ per hour (≈1.3); (c) water also lost as vapour in exhaled breath; (d) less sweat evaporates, so less energy is transferred away from the skin by evaporation.
Examiner tip: Remember the water drunk was ADDED to his mass, so it must be added back on: 1.3 + 0.3, not 1.3 − 0.3.

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