AQA GCSE Biology Biology Paper 1 (Higher), June 2023: Question 2

19 marks · Standard Demand difficulty · Extended Answer

Identify heart chambers and pacemaker location, compare blood vessel structures, graph and analyze coronary blockage data, and explain the effects and treatments of coronary heart disease.

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Question

Question 2 on the circulatory system across multiple parts. Figure 1 shows a cross-section of the human heart with chambers labeled A, B, C, and D. Questions 02.1 to 02.3 ask about heart chambers and pacemaker location. Figure 2 shows cross-sections of an artery and vein with elastic and muscle tissues labeled, followed by question 02.4 asking for structural differences. Table 2 provides data for percentage blockage of a coronary artery against blood flow in cm³/minute. Question 02.5 asks to describe the trend, 02.6 asks to plot this data on the provided grid in Figure 3, 02.7 asks to predict blood flow at 35% blockage, 02.8 is a 6-mark question to explain the effect of a partly blocked coronary artery on the body, and 02.9 asks how one treatment works.
Question text

02 This question is about the circulatory system.

Figure 1 shows the human heart.

Figure 1

02.1 Which part of the heart receives oxygenated blood from the lungs?

[1 mark]

Tick ( ) one box.

A B C D

02.2 Which part of the heart pumps deoxygenated blood to the lungs?

[1 mark]

Tick ( ) one box.

A B 9 C D

02.3 A group of cells called the pacemaker controls the resting heart rate.

Where in the heart is the pacemaker found?

[1 mark]

Tick ( ) one box.

*08* Left atrium

Left ventricle

Right atrium

Right ventricle

02.4 Figure 2 shows a cross section of an artery and of a vein.

Figure 2

Describe two ways that the structure of an artery is different from the structure

of a vein.

[2 marks]

02.5 In coronary heart disease, the coronary arteries become narrower.

A build-up of fatty material can cause a blockage in a coronary artery.

Table 2 shows how a blockage in a coronary artery affects blood flow.

Table 2

Percentage (%) of coronary 3

Blood flow in cm /minute

artery that is blocked

0 100

10 64

20 42

50 8

80 2

Describe the trend shown in Table 2.

[1 mark]

02.6 Complete Figure 3.

You should:

• use a suitable scale for the y-axis

• plot the data from Table 2

• draw a line of best fit.

[4 marks]

Figure 3

02.7 Predict the blood flow in a coronary artery with a 35% blockage.

Use Figure 3.

[1 mark]

Blood flow =12 3

cm /minute

02.8 Explain the effect of a partly blocked coronary artery on the human body.

[6 marks]

02.9 There are different treatments for a blockage in a coronary artery.

Explain how one treatment for a blockage in a coronary artery works.

[2 marks]

Mark scheme

Show the mark scheme Mark scheme for Question 2 totaling 19 marks. 02.1 accepts A (1 mark). 02.2 accepts C (1 mark). 02.3 accepts right atrium (1 mark). 02.4 gives 2 marks for any two: thicker muscle tissue, thicker elastic tissue, narrower lumen, or lack of valves in artery. 02.5 awards 1 mark for noting as percentage blockage increases, blood flow decreases. 02.6 awards 4 marks: 1 for suitable scale covering at least 50% of the axis, 2 for all points plotted correctly, and 1 for a correct curved line of best fit. 02.7 awards 1 mark for reading from the student's line (allow 18 to 24 cm³/min if no line). 02.8 is a 6-mark levels-of-response question covering reduced oxygen/glucose, reduced aerobic respiration, more anaerobic respiration, tiredness/breathlessness, and lactic acid buildup. 02.9 gives 2 marks for naming a treatment and explaining how it works (e.g. statins reduce blood cholesterol, or stents keep arteries open).

Question 2

AO /

Question Answers Extra information Mark

Spec Ref.

02.1 A 1 AO1

4.2.2.2

AO /

Spec Ref.

02.2 C 1 AO1

4.2.2.2

AO /

Spec Ref.

02.3 right atrium 1 AO1

4.2.2.2

AO /

Spec Ref.

allow converse if clearly

02.4 AO1

referring to a vein

4.2.2.2

any two from: 2

• (artery) has a thicker muscle

(tissue) if neither mark awarded

• (artery) has a thicker elastic allow 1 mark for artery

(tissue) has a thicker wall

• (artery) has a narrower lumen allow description of lumen

• (artery) does not contain

valves

AO /

Spec Ref.

02.5 as the percentage of the allow converse 1 AO2

(coronary) artery that is blocked 4.2.2.2

allow the greater the blockage,

increases, blood flow decreases

the less blood flows

allow negative correlation or

inversely proportional

allow as one increases, the

other decreases

10 AO /

Spec Ref.

02.6 scale on y-axis must take up at least 50% of 1 AO2

axis 4.2.2.2

all points plotted allow 3 or 4 correct plots for 1 2

mark

allow a tolerance of ± ½ small

square

correct curved line of best fit ignore line joined point to point 1

with straight lines

ignore extrapolation

AO /

Spec Ref.

02.7 correct answer from student's allow a tolerance of ± ½ small 1 AO3

line in Figure 3 square 4.2.2.2

if no line drawn on Figure 3,

allow a value from 18 to 24

(cm3/minute)

AO /

Question Answers Mark

Spec Ref.

02.8 Level 3: Relevant points (reasons / causes) are identified, given in 5-6 AO1

detail and logically linked to form a clear account. AO2

4.2.2.2

Level 2: Relevant points (reasons / causes) are identified, and 3-4 4.2.2.4

there are attempts at logical linking. The resulting account is not

4.4.2.1

fully clear.

4.4.2.2

Level 1: Points are identified and stated simply, but their relevance 1-2

is not clear and there is no attempt at logical linking.

No relevant content. 0

Indicative content:

• reduced blood flow to heart (muscle / tissue / cells)

• (so) less oxygen to heart (muscle / tissue / cells)

• (so) less glucose to heart (muscle / tissue / cells)

• (so) less (aerobic) respiration (in heart / body cells)

• (more) anaerobic respiration

• (so) less energy (released)

• (so) less muscle contraction

• (so) less blood / oxygen / glucose around the body (from heart)

or slower flow of blood / oxygen / glucose to body (from heart)

• less carbon dioxide removed from body (muscle / tissue / cells)

• (resulting in) breathlessness

• (resulting in) tiredness

• (anaerobic respiration causes) production of lactic acid

• (build-up of lactic acid) causes muscle fatigue / pain or chest

pain

For Level 3, students must explain the effect of reduced oxygen /

glucose on respiration or energy release and its consequence

AO /

Spec Ref.

02.9 any one pair from: mark as a pair AO1

4.2.2.4

• (insert) stent(s) allow description 1

(to) open (coronary) artery ignore unblock (coronary) artery 1

• (prescribe) statins (1)

(to) reduce (blood) allow to slow down the rate of

cholesterol (1) fatty material deposit

12 • heart (and lung) transplant (1)

(to) replace the diseased

heart with a healthy heart (1)

• use an artificial heart (1)

(to) keep the patient alive allow (artificial heart)

while waiting for a transplant pumps blood around the

(1) body in place of the heart

• (artery / heart) bypass (1) allow description

(to) divert blood around the

blockage (1)

Total Question 2 19

How to answer it

The Circulatory System, Heart Structure & Coronary Heart Disease

📌 What this question tests

This 19-mark question assesses core knowledge of AQA Specification 4.2.2.2 (The Heart and Blood Vessels) and 4.2.2.4 (Coronary Heart Disease):

  • Identifying internal heart chambers and blood flow pathways.
  • Location and role of the natural pacemaker cells.
  • Structural adaptations comparing arteries and veins.
  • Data handling: describing trends, scaling axes, plotting line graphs, and curve reading.
  • Extended multi-step explanation (6-mark level of response) linking reduced coronary blood supply to cellular respiration and bodily symptoms.
  • Medical treatments for cardiovascular disease (stents, statins, bypass, transplants).

Parts 02.1, 02.2 & 02.3: Heart Anatomy & Pacemaker

Identifying chambers and electrical control [3 marks total]

✅ Correct Selections

  • 02.1: Box A (Left atrium receives oxygenated blood from the pulmonary vein) [1 mark]
  • 02.2: Box C (Right ventricle pumps deoxygenated blood to lungs via pulmonary artery) [1 mark]
  • 02.3: Right atrium [1 mark]

💡 Key Knowledge: Diagram Orientations

  • Anatomical position: Diagrams are shown as if looking at a patient's chest. The left side of the diagram is the right side of the heart, and the right side of the diagram is the left side.
  • A: Left atrium (receives oxygenated blood)
  • B: Left ventricle (thickest muscular wall; pumps to body)
  • C: Right ventricle (pumps to lungs)
  • D: Right atrium (receives deoxygenated blood via vena cava; houses the pacemaker)

🧠 Exam Technique

Remember LORD: Left Oxygenated, Right Deoxygenated. Also remember Atria are at the top (entry chambers), Ventricles are at the bottom (pumping chambers).

❌ Common Errors

Confusing anatomical left and right, or confusing the left ventricle (thick wall) with the right ventricle. Placing the pacemaker in the left atrium or brain instead of the right atrium wall.

Part 02.4: Blood Vessel Structure

Comparing an artery to a vein [2 marks]

✅ Correct Answers (Any two points)

  • (Artery) has thicker muscle tissue.
  • (Artery) has thicker elastic tissue.
  • (Artery) has a narrower lumen (central bore/hole).
  • (Artery) does not contain valves (veins have valves).
Note: The converse is allowed if explicitly referring to the vein (e.g. "a vein has a wider lumen"). Saying only "thicker wall" gains a maximum of 1 mark if neither muscle nor elastic tissue is named.

💡 Structural Reasons

Arteries: Carry blood under high pressure away from the heart. They need thick muscle to withstand pressure and elastic fibres to stretch and recoil.

Veins: Carry blood at low pressure back to the heart. They have wide lumens to reduce resistance to flow and valves to prevent backflow.

❌ Common Errors

  • Vague statements like "one is bigger than the other" or "arteries have cell walls" (animal tissues do not have cell walls!).
  • Describing function (e.g., "carries oxygenated blood") instead of structure. Always re-read the command word: "structure".

Parts 02.5, 02.6 & 02.7: Data Analysis & Graph Skills

Trend, plotting, and interpolation [6 marks total]

✅ 02.5: Trend in Table 2 [1 mark]

"As the percentage of coronary artery that is blocked increases, blood flow decreases."

Also acceptable: "negative correlation" or "inversely proportional".

📐 02.6: Graph Construction Steps [4 marks]

  1. Scale (1 mark): Choose a sensible, linear scale on the vertical y-axis (Blood flow in cm³/minute). E.g., 0 to 100 with 10 or 20 units per major grid square. Must occupy at least 50% of the grid height.
  2. Plotting Points (2 marks): Plot all five coordinates accurately within ± ½ small square:
    • (0, 100)
    • (10, 64)
    • (20, 42)
    • (50, 8)
    • (80, 2)
    (3 or 4 points plotted correctly scores 1 mark).
  3. Line of Best Fit (1 mark): Draw a single, smooth, continuous curved line passing through or very close to all points.

📐 02.7: Reading from Graph [1 mark]

Predicted blood flow at 35% blockage:

  • Go along the x-axis to 35%.
  • Draw a vertical line up to intersect your drawn curve.
  • Read horizontally across to the y-axis.
  • Expected value: typically between 18 and 24 cm³/minute (exact value awarded based on the student's curve ± ½ small square).

❌ Graph Plotting Traps

  • Ruler line: Joining points with straight lines (dot-to-dot) or forcing a straight line of best fit when data clearly shows a curve.
  • Inconsistent scale: Writing values from the table directly onto axis grid lines instead of using equal numerical intervals.
  • Feathered lines: Sketchy, thick, or multiple overlapping pencil lines lose the line of best fit mark.

Part 02.8: Extended Response (6 Marks)

Explain the effect of a partly blocked coronary artery on the human body

Level of Response: 6 Marks

💡 The Logical Cause-and-Effect Chain

To reach Level 3 (5–6 marks), you must build a connected, step-by-step biological explanation linking the blockage to cellular respiration and physical symptoms:

Narrowed lumen → Reduced blood flow → Less O₂ & glucose to heart muscle cells → Less aerobic respiration & less energy released → Anaerobic respiration / Lactic acid → Muscle fatigue / Angina / Heart attack → Reduced cardiac output → Whole-body tiredness & breathlessness

✅ Model Answer Plan (Indicative Points)

  • 1. Delivery: Less blood flows through the coronary arteries to the heart muscle cells.
  • 2. Supply: Less oxygen and less glucose reach the heart muscle.
  • 3. Cellular Respiration: Less aerobic respiration occurs in the heart muscle cells, releasing less energy (ATP).
  • 4. Pumping efficiency: The heart cannot contract as strongly, so less blood is pumped to the rest of the body.
  • 5. Anaerobic respiration: Heart muscle cells may respire anaerobically, producing lactic acid.
  • 6. Symptoms:
    • Lactic acid causes muscle fatigue and severe chest pain (angina).
    • Body cells receive less oxygen/glucose, causing tiredness and fatigue.
    • Breathing rate increases (breathlessness) to compensate for oxygen shortage and to clear lactic acid / CO₂.

❌ Examiner Pitfalls to Avoid

  • Saying respiration "creates" or "makes" energy: Always state that respiration releases energy. Energy cannot be created.
  • Vague "lack of oxygen": You must specify that oxygen goes to the heart muscle cells for respiration.
  • Missing the biological link: Simply listing symptoms (pain, tiredness) without explaining respiration and energy release limits the answer to Level 1 or 2 (maximum 2–4 marks).

Part 02.9: Treatments for Blocked Coronary Arteries

Explain how one treatment works [2 marks]

🧠 Strategy: Select One Treatment and State its Mechanism

This is marked as a pair: 1 mark for naming the treatment, 1 mark for correctly explaining how it works.

Option A: Stents

  • Treatment: Insert a stent [1 mark]
  • Mechanism: Keeps the coronary artery open / widens the lumen so blood flows freely [1 mark]
  • Do not write: "unblocks the artery".

Option B: Statins

  • Treatment: Prescribe statins [1 mark]
  • Mechanism: Lowers/reduces blood cholesterol, slowing down the deposit of fatty material [1 mark]

Option C: Bypass Surgery

  • Treatment: Coronary bypass surgery [1 mark]
  • Mechanism: Uses another blood vessel to divert/route blood around the blocked section [1 mark]

Option D: Heart Transplant

  • Treatment: Donor heart transplant [1 mark]
  • Mechanism: Replaces the damaged/diseased heart with a healthy donor heart [1 mark]

Option E: Artificial Heart

  • Treatment: Artificial heart [1 mark]
  • Mechanism: Mechanically pumps blood around the body to keep the patient alive while waiting for a transplant [1 mark]

Topics

Biology · B2: Organisation · B4: Bioenergetics

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 1 (Higher), June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.