Heart, blood vessels, blood and lungs – GCSE Biology exam questions with mark scheme

1Grade 4–54 marks

(a) Name the blood vessel that carries blood from the heart to the lungs. [1]

(b) The wall of the left ventricle is thicker than the wall of the right ventricle. Explain why. [2]

(c) The natural resting heart rate is controlled by a group of cells in the right atrium. Name this group of cells. [1]

(a) pulmonary artery; do not accept pulmonary vein(1)
(b) left ventricle pumps blood (out) around the whole body / further, whereas the right ventricle pumps blood only to the lungs; allow left ventricle pumps blood to the (rest of the) body (comparison with the right ventricle not required)(1)
(b) so (more muscle) gives a stronger / more forceful contraction / pumps blood at a higher pressure; ignore 'pumps harder' alone(1)
(c) pacemaker (cells); accept sinoatrial node / SAN(1)
Answer: (a) pulmonary artery (b) pumps to the whole body so needs higher pressure (c) pacemaker
Examiner tip: 'Pumps harder' is not enough — link the thicker muscle to higher pressure and the longer distance (whole body).

2Grade 4–54 marks

Gas exchange in the lungs takes place in the alveoli.

Explain how the alveoli are adapted for efficient gas exchange. [4]

(very many alveoli give) a large surface area for diffusion(1)
thin walls / one cell thick, so short diffusion distance(1)
good blood supply / many capillaries to maintain a steep concentration gradient (by carrying oxygen away / bringing carbon dioxide)(1)
ventilation (breathing) brings in fresh air to maintain the concentration gradient; accept moist surface so gases dissolve(1)
Answer: Large surface area; thin walls (short diffusion distance); rich capillary network and ventilation maintain the concentration gradient.
Examiner tip: For 'explain' each feature must be linked to its effect — 'thin walls' alone scores less than 'thin walls so a short diffusion distance'.

3Grade 1–3Foundation5 marks

Blood is a tissue.

(a) Draw one line from each part of the blood to its function. [4]

Part of the blood	Function
plasma	carries oxygen
platelets	controls the resting heart rate
red blood cells	helps the blood to clot
white blood cells	destroys pathogens
	carries dissolved substances such as carbon dioxide, urea and glucose

(b) What is meant by a tissue? [1]

(a) plasma → carries dissolved substances such as carbon dioxide, urea and glucose
if more than one line is drawn from a part of the blood, that line scores 0(1)
(a) platelets → helps the blood to clot(1)
(a) red blood cells → carries oxygen(1)
(a) white blood cells → destroys pathogens
'controls the resting heart rate' is the distractor (pacemaker cells) and should not be linked(1)
(b) a group of cells with a similar structure and function
allow (group of) similar cells working together to carry out a (particular) function
do not accept 'a group of organs' / 'a group of tissues'(1)
Answer: (a) plasma – dissolved substances; platelets – clotting; red blood cells – oxygen; white blood cells – destroy pathogens (b) a group of cells with a similar structure and function
Examiner tip: Two lines from the same box cancel each other out — and the extra option in the right-hand box is there to catch guessers (resting heart rate is the pacemaker's job, not the blood's).

4Grade 1–3Foundation5 marks

The diagram shows how blood flows around the human body.

W, X, Y and Z are the four chambers of the heart. A, B, C and D are blood vessels. The arrows show the direction of blood flow.

(a) Name blood vessel A and blood vessel D. [2]

(b) Which chamber pumps blood to the lungs? Give the letter. [1]

(d) The heart muscle is supplied with oxygen by its own blood vessels. Name these blood vessels. [1]

(a) A: vena cava
accept vena cavae / superior or inferior vena cava
ignore 'vein' on its own(1)
(a) D: aorta
ignore 'artery' on its own(1)
(b) Y
accept 'right ventricle' only if the letter Y is also given or clearly intended(1)
(c) blood passes through the heart twice for each complete circuit (of the body)
allow one circuit (from heart) to the lungs and (back), one circuit to the (rest of the) body
do not accept 'the heart has two sides' on its own(1)
(d) coronary arteries
allow coronary artery
ignore 'coronary veins' / 'coronary vessels'(1)
Answer: (a) A vena cava, D aorta (b) Y (c) blood goes through the heart twice in one complete circuit (d) coronary arteries
Examiner tip: Follow the arrows rather than relying on left and right: blood from the body (A) enters the heart, and the chamber that sends blood up to the lungs is the one at the start of vessel B.

5Grade 4–56 marks

A doctor used an ultrasound scanner to measure blood flow in an artery in a patient's thigh.

While the patient was resting, 150 cm³ of blood flowed through the artery in 30 seconds.

(a) Calculate the rate of blood flow in cm³ per second. [2]

(b) Calculate the volume of blood that would flow through the artery in 1 hour at this rate.

Give your answer in dm³. (1 dm³ = 1000 cm³) [2]

Calculate the percentage increase in the rate of blood flow. [2]

(a) 150 ÷ 30(1)
(a) = 5 (cm³/s)
an answer of 5 scores 2 marks(1)
(b) 5 × 3600 = 18 000 (cm³)
allow ecf from (a)
allow 5 × 60 × 60(1)
(b) 18 (dm³)
an answer of 18 scores 2 marks
allow ecf: their (a) × 3.6(1)
(c) (9 − 5) ÷ 5 (× 100)
allow ecf from (a)(1)
(c) 80 (%)
an answer of 80 scores 2 marks
do not accept 180 (%)(1)
Answer: (a) 5 cm³/s (b) 18 dm³ (c) 80%
Examiner tip: In (b) convert the hour to seconds before multiplying, then divide by 1000 — many students stop at 18 000 and lose the final mark for the unit.

6Grade 4–58 marks

The table shows information about three types of blood vessel, X, Y and Z.

Blood vessel	Thickness of wall in mm	Diameter of lumen in mm	Valves present
X	1.2	3.0	no
Y	0.001	0.008	no
Z	0.6	6.0	yes

(a) Identify blood vessels X, Y and Z. [2]

(b) Explain how the wall of vessel X is related to its function. [2]

(d) Explain why vessel Z needs valves. [2]

(a) Y = capillary(1)
(a) X = artery and Z = vein (both needed for this mark)(1)
(b) (X has a) thick wall
allow thick layers of muscle / elastic fibres
ignore 'strong' on its own(1)
(b) to withstand the high pressure (of blood pumped out of the heart / ventricles)
allow elastic fibres stretch and recoil (to maintain the pressure / even out the flow)
do not accept 'to pump blood' (arteries do not pump)(1)
(c) wall is (only) one cell thick / very thin
accept the value 0.001 mm from the table(1)
(c) (so there is a) short diffusion distance (between blood and tissue cells)
allow so substances such as oxygen / glucose / carbon dioxide can diffuse in or out quickly(1)
(d) blood (in veins) is at low pressure(1)
(d) (valves) prevent the backflow of blood
allow keep blood flowing (back) towards the heart
ignore 'stop blood going the wrong way' unless direction is explained(1)
Answer: (a) X artery, Y capillary, Z vein (b) thick muscular/elastic wall to withstand high pressure (c) one cell thick so short diffusion distance (d) blood at low pressure so valves stop backflow
Examiner tip: In (b) arteries do not pump blood — say they withstand high pressure; and in (c) 'thin wall' only gets the second mark when linked to a short diffusion distance.

7Grade 6–7Higher7 marks

Fish have a single circulatory system. Blood is pumped from the heart to the gills and then flows straight on to the rest of the body before returning to the heart.

Humans have a double circulatory system.

The table shows the mean blood pressure in some blood vessels of a fish and of a human.

Organism	Blood vessel	Mean blood pressure in kPa
fish	vessel leaving the heart (to the gills)	4.0
fish	vessel leaving the gills (to the body)	2.4
human	pulmonary artery	2.0
human	aorta	12.6

(a) Calculate the percentage decrease in blood pressure as blood passes through the gills of the fish. [2]

(b) Use the data to explain the advantage to humans of having a double circulatory system. [3]

(c) A frog's heart has two atria but only one ventricle. Blood from the lungs and blood from the body both enter this ventricle.

Suggest one disadvantage of having only one ventricle. [2]

(a) (4.0 − 2.4) ÷ 4.0 (× 100)
allow 1.6 ÷ 4.0(1)
(a) 40 (%)
an answer of 40 scores 2 marks
do not accept 60 (%)(1)
(b) blood going to the (rest of the) body is at a much higher pressure in humans (12.6 kPa) than in fish (2.4 kPa)
allow about 5 times higher
must use data for this mark(1)
(b) because blood returns to the heart after the lungs and is pumped again (by the left ventricle)
allow pressure lost in the lungs / gills is restored(1)
(b) so blood / oxygen / glucose reaches the (body) tissues / cells more quickly / at a faster rate (for respiration)
allow lower pressure in the pulmonary artery (2.0 kPa) prevents damage to the (delicate) capillaries / alveoli in the lungs(1)
(c) oxygenated blood and deoxygenated blood (would) mix (in the ventricle)
allow blood from the lungs and blood from the body mix(1)
(c) so blood pumped to the body / muscles contains less oxygen
allow so less (aerobic) respiration (in cells) / less energy released
ignore 'less blood' / 'slower blood'(1)
Answer: (a) 40% (b) human body circulation is at 12.6 kPa v 2.4 kPa in fish because blood is re-pumped after the lungs, so oxygen reaches tissues faster (c) oxygenated and deoxygenated blood mix, so blood to the body carries less oxygen
Examiner tip: 'Use the data' means you must quote numbers — then link the higher pressure to blood being pumped a second time after the lungs.

8Grade 6–78 marks

The diagram shows some cells from a sample of human blood, as seen through a light microscope.

(a) Name the parts of the blood labelled J, K and L. [3]

(b) Cell J has no nucleus and a biconcave disc shape.

Explain how each of these features helps cell J to carry out its function. [2]

(c) A healthy adult has $5.2 \times 10^{6}$ red blood cells and $6.5 \times 10^{3}$ white blood cells in each mm³ of blood.

Calculate the ratio of red blood cells to white blood cells.

Give your answer in the form x : 1 [2]

(d) A patient has a much lower number of white blood cells than normal.

Suggest why this patient is more likely to become ill. [1]

(a) J: red blood cell
allow erythrocyte(1)
(a) K: white blood cell
allow phagocyte / neutrophil / leucocyte
do not accept lymphocyte (nucleus is lobed)(1)
(a) L: platelets
allow cell fragments
ignore 'cell(s)' after platelet(s)(1)
(b) no nucleus: more space / room for haemoglobin (so more oxygen carried)(1)
(b) biconcave: large(r) surface area (to volume ratio) for oxygen to diffuse in / out (quickly)
ignore 'to fit through capillaries'
if neither feature is linked correctly, allow 1 mark for 'contains haemoglobin which combines with / carries oxygen'(1)
(c) $5.2 \times 10^{6} \div 6.5 \times 10^{3}$
allow 5 200 000 ÷ 6500(1)
(c) 800 : 1
an answer of 800 : 1 scores 2 marks
allow 800 for 1 mark if not written as a ratio(1)
(d) fewer pathogens destroyed / killed (so infection more likely)
allow less phagocytosis / fewer antibodies or antitoxins produced
ignore 'weaker immune system' on its own(1)
Answer: (a) J red blood cell, K white blood cell, L platelets (b) no nucleus – more room for haemoglobin; biconcave – larger surface area for oxygen diffusion (c) 800 : 1 (d) fewer pathogens destroyed, so more infections
Examiner tip: In (b) each feature needs its own consequence (no nucleus → more room for haemoglobin; biconcave → larger surface area for diffusion) — just describing the shape again scores nothing.

9Grade 6–76 marks

Muscle cells in the leg need oxygen for aerobic respiration.

Describe the route taken by a molecule of oxygen from the air outside the body to a muscle cell in the leg.

In your answer, name the structures in the lungs, heart and blood vessels that the oxygen passes through. [6]

air (breathed in) through the mouth / nose and down the trachea(1)
into the (two) bronchi (and bronchioles)(1)
into the alveoli (air sacs)(1)
oxygen diffuses (down a concentration gradient) across the alveolus wall and the capillary wall into the blood(1)
oxygen enters red blood cells and combines with / binds to haemoglobin(1)
carried in the pulmonary vein to the heart(1)
enters the left atrium, then passes into the left ventricle (through a valve)(1)
left ventricle contracts and pumps blood out through the aorta(1)
travels through arteries to the leg (then into capillaries)(1)
oxygen diffuses out of the capillaries (from high to low concentration) into the muscle cell(1)

Level	Marks	What it looks like
Level 3	5–6	A clear, logically ordered description of the whole route from the air to the muscle cell. Structures in the lungs, the correct side and chambers of the heart and the main vessels are named in the right sequence, and diffusion is described at both the alveoli and the muscle tissue.
Level 2	3–4	A description of most of the route with some correctly named structures in order, but with gaps or one significant error (for example, the wrong side of the heart, or diffusion described at only one end).
Level 1	1–2	Some relevant, isolated points, such as naming the lungs or alveoli, the heart or red blood cells, with little or no correct sequence.
No relevant content	0	Nothing worthy of credit.

Answer: Trachea → bronchi → alveoli → diffuses into capillary blood and binds haemoglobin in red blood cells → pulmonary vein → left atrium → left ventricle → aorta → arteries → capillaries in the leg → diffuses into the muscle cell.
Examiner tip: A Level 3 answer gets the heart order right (pulmonary vein → left atrium → left ventricle → aorta) — students who send oxygenated blood into the right side of the heart, or into the pulmonary artery, cap themselves at Level 2.

10Grade 8–9Higher9 marks

The graph shows how the pressure of the blood inside the left ventricle of a healthy person changed over 2.4 seconds.

(a) Use the graph to calculate the person's heart rate in beats per minute. [2]

(b) Each time the left ventricle contracts it pumps out 70 cm³ of blood.

Calculate the volume of blood pumped out of the left ventricle in one minute. Give your answer in dm³. [2]

(c) A different person has a resting heart rate of 40 beats per minute because their pacemaker cells are not working properly. Each contraction of their left ventricle pumps out 70 cm³ of blood.

Calculate the percentage decrease in the volume of blood pumped per minute compared with your answer to (b). [2]

(d) The person in (c) feels tired and weak, even when doing light exercise. Doctors fit an artificial pacemaker.

Explain why the person feels tired and how the artificial pacemaker helps. [3]

(a) time for one beat = 0.8 s (e.g. between peaks at 0.3 s and 1.1 s)
allow 3 beats in 2.4 s(1)
(a) 60 ÷ 0.8 = 75 (beats per minute)
an answer of 75 scores 2 marks(1)
(b) 70 × 75 = 5250 (cm³)
allow ecf from (a)(1)
(b) 5.25 (dm³)
allow 5.3
an answer of 5.25 scores 2 marks(1)
(c) volume = 70 × 40 = 2800 (cm³) and (5250 − 2800) ÷ 5250 (× 100)
allow ecf from (b)
allow (75 − 40) ÷ 75 (× 100)(1)
(c) 46.7 (%)
allow 46.6 to 47 / 46.66…
an answer in this range scores 2 marks(1)
(d) less blood pumped (per minute) so less oxygen / glucose delivered to (muscle) cells(1)
(d) so less (aerobic) respiration (in muscle cells) so less energy is released / transferred (for contraction)
allow more anaerobic respiration / lactic acid produced(1)
(d) artificial pacemaker is an electrical device that (sends electrical impulses to) make the heart beat at a normal / faster / regular rate
allow corrects irregularities in the heart rate(1)
Answer: (a) 75 beats per minute (b) 5.25 dm³ (c) 46.7% (d) less blood, so less oxygen/glucose to muscles, less respiration and energy released; the pacemaker is an electrical device that makes the heart beat at a normal regular rate
Examiner tip: Read the time for ONE whole cycle from peak to peak (or count several beats and divide) — reading the time of a single contraction phase instead of the full cycle is the commonest error.

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