OxfordAQA International AS and A-level Biology: Blood vessels, the heart and coronary heart disease (9610) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions follow sections 3.2.6 and 3.2.7 of the OxfordAQA International AS and A-level Biology (9610) specification, Version 5.1. Read the study guide or the revision notes first. Course links: OxfordAQA A-level Biology hub and the printable checklist.

Questions

1. Give two differences between the structure of a vein and of an artery, and relate each to function. [4]

2. A photograph of a capillary shows its width as 40 mm at a magnification of x8000.

(a) Calculate the real width in micrometres. [2] (b) Explain how the structure of a capillary makes it suited to metabolic exchange. [3]

3. In a capillary bed the hydrostatic pressure is 3.9 kPa at the arteriole end and 1.4 kPa at the venule end. The effect of plasma proteins draws fluid in with a pressure of 3.0 kPa throughout.

(a) Calculate the net pressure at each end and state the direction of fluid movement. [2] (b) Explain how tissue fluid forms. [2] (c) Explain how fluid returns to the blood and what happens to the remainder. [2]

4. (a) Name the vessel that carries blood from the right ventricle and the valve that prevents backflow into the ventricle. [2] (b) Explain why the wall of the left ventricle is thicker than that of the right. [2] (c) State the function of the coronary arteries. [1]

5. The table gives data for the left side of a heart in a cycle of 0.60 s. End-diastolic volume is 138 cm³ and end-systolic volume is 66 cm³.

Time / s	Atrium / kPa	Ventricle / kPa	Aorta / kPa
0.04	1.3	0.7	10.9
0.10	1.1	8.0	10.5
0.20	1.5	17.2	16.6
0.32	2.3	3.0	11.9
0.50	1.7	0.5	10.6

(a) State the position of each valve at 0.20 s. [2] (b) Explain why both valves are closed at 0.32 s. [2] (c) Calculate the stroke volume, the heart rate and the cardiac output in dm³ per minute. [4]

6. A trained athlete has a resting heart rate of 52 beats per minute and a stroke volume of 95 cm³. An untrained person has 70 beats per minute and 68 cm³.

(a) Calculate the cardiac output of each in dm³ per minute. [2] (b) Calculate how much higher the athlete’s stroke volume is, as a percentage of the untrained person’s. [1] (c) Explain how the athlete can have a lower heart rate but a similar cardiac output. [2]

7. Explain how atheroma can lead to an aneurysm and to thrombosis. [4]

8. Atheroma narrows an artery’s lumen diameter from 3.6 mm to 2.7 mm. Calculate the percentage reduction in diameter and in cross-sectional area. [4]

9. Explain how a thrombus in a coronary artery causes a myocardial infarction. [4]

10. A study followed adults for several years. The table shows new cases of CHD per 1000 person-years.

Cigarettes per day	0	1 to 14	15 to 24	25 or more
CHD cases per 1000 person-years	3.4	5.9	8.8	11.2

(a) Calculate how many times greater the rate is in the 15 to 24 group than in non-smokers. [2] (b) Describe the trend shown. [2] (c) A newspaper says the data prove smoking causes CHD. Evaluate this claim. [3]

11. Five volunteers had their pulse rate measured at rest and after 2 minutes of stepping. Rest (beats per minute): 68, 72, 64, 75, 71. After stepping: 112, 125, 108, 131, 119.

(a) Calculate the mean at rest, the mean after stepping, and the percentage increase. [3] (b) State two variables that should be controlled. [2] (c) State one precaution for volunteers. [1]

12. A man smokes, eats a diet high in saturated fat and has high blood pressure. Explain how each of these may increase his risk of CHD. [6]

Answers

1. Veins have thinner walls with less elastic tissue [1] because blood is at low pressure [1]; veins have valves [1] to prevent backflow of blood [1]. Also allow wider lumen with less resistance to flow. [4] Examiner insight: Each difference needs its own linked function; a list of differences with no function is likely to lose marks.

2. (a) 40 mm = 40 000 micrometres [1]; 40 000 / 8000 = 5.0 micrometres [1]. (b) The wall is one cell thick, so a short diffusion distance [1]; the diameter allows red cells to pass slowly in single file [1]; gaps between cells let fluid and solutes pass out [1]. Allow large total surface area. [5] Examiner insight: Write the unit conversion before dividing; a bare answer in the wrong unit loses credit even when the digits are right.

3. (a) Arteriole end: 3.9 - 3.0 = 0.9 kPa out [1]. Venule end: 1.4 - 3.0 = -1.6 kPa, so into the capillary [1]. (b) High hydrostatic pressure forces fluid out [1] through gaps in the wall, leaving red cells and large proteins behind [1]. (c) The proteins lower the water potential of the blood, so water returns by osmosis [1]; the excess drains into lymph vessels and is returned to the blood [1]. [6] Examiner insight: Name the two forces separately (hydrostatic pressure and the protein effect on water potential), not just “pressure”.

4. (a) Pulmonary artery [1]; semilunar valve [1]. (b) The left ventricle pumps blood around the whole body [1], so it must generate higher pressure through greater muscle contraction [1]. (c) They supply the cardiac muscle with oxygenated blood [1]. [5] Examiner insight: Say semilunar, not just “valve”, and say the pulmonary artery carries blood to the lungs.

5. (a) Atrioventricular valve closed [1]; semilunar valve open [1] (ventricle 17.2 above aorta 16.6). (b) Ventricular pressure (3.0) is below the aorta (11.9), so the semilunar valve is closed [1]; but it is above atrial pressure (2.3), so the atrioventricular valve is closed [1]. (c) Stroke volume = 138 - 66 = 72 cm³ [1]. Heart rate = 60 / 0.60 = 100 beats per minute [1]. Cardiac output = 72 x 100 = 7200 cm³ per minute [1] = 7.2 dm³ per minute [1]. [8] Examiner insight: Quote the pressure pair from the table when justifying a valve state; the claim alone is weaker than the comparison.

6. (a) Athlete: 52 x 95 = 4940 cm³, 4.94 dm³ per minute [1]. Untrained: 70 x 68 = 4760 cm³, 4.76 dm³ per minute [1]. (b) (95 - 68) / 68 x 100 = 40 % [1]. (c) The athlete’s heart pumps more blood per beat [1], so fewer beats are needed per minute for the same output [1]. [5] Examiner insight: “Stronger heart” earns less than a statement that stroke volume is larger so heart rate can be lower.

7. Atheroma weakens the artery wall [1]; at high pressure the wall bulges as an aneurysm [1] which may burst [1]. Atheroma damages the lining of the artery, which starts clotting [1] so a thrombus forms. Allow any four of these points. [4] Examiner insight: Link each condition to a stated change in the wall; “atheroma causes both” alone is a bare assertion.

8. Diameter: (3.6 - 2.7) / 3.6 x 100 = 25 % [1]. Area before = pi x 1.8² = 10.18 mm² [1]; area after = pi x 1.35² = 5.73 mm² [1]. Reduction = (10.18 - 5.73) / 10.18 x 100 = 44 % [1]. [4] Examiner insight: Use radius, not diameter, in pi x r²; a diameter slip gives wrong areas for both before and after.

9. Atheroma damages the lining, and a thrombus forms [1]. It blocks the coronary artery [1] so blood flow to part of the cardiac muscle is interrupted [1]. The muscle is deprived of oxygen and glucose and dies [1]. [4] Examiner insight: “Heart attack” is not an explanation; the interruption of blood flow to cardiac muscle must be stated.

10. (a) 8.8 / 3.4 [1] = 2.6 times [1]. (b) The rate of CHD rises as the number of cigarettes per day rises [1], from 3.4 in non-smokers to 11.2 at 25 or more, with figures quoted [1]. (c) The data show a positive correlation, not proof of cause [1]; other variables such as age, diet or activity may differ between groups [1]; a plausible mechanism (damage to artery lining, carbon monoxide) and larger controlled studies would strengthen the claim [1]. [7] Examiner insight: An evaluation needs a point about the data and a point about missing information; “it is only a correlation” alone is too thin.

11. (a) Mean at rest = 350 / 5 = 70.0 [1]; mean after = 595 / 5 = 119.0 [1]; increase = 49 / 70 x 100 = 70 % [1]. (b) Any two: same exercise duration and step height; same volunteers; time of day; caffeine; counting time [2]. (c) Volunteers must be free to stop, or not take part if unwell or with a heart condition [1]. [6] Examiner insight: Name the variable and say how it is kept constant; “fair test” is not a control.

12. Smoking: carbon monoxide reduces oxygen carried by haemoglobin [1], and nicotine raises heart rate and narrows vessels, or damages the lining [1]. Diet: saturated fat raises blood cholesterol [1] so lipid deposits build up in artery walls as atheroma [1]. High blood pressure: damages the artery lining [1], promoting atheroma and stressing weakened walls [1]. [6] Examiner insight: Each factor needs a mechanism linking to atheroma, reduced oxygen supply or artery damage.

Where marks are usually lost

• Not converting micrometres and millimetres before dividing by magnification.
• Writing “pressure” without saying hydrostatic pressure or water potential.
• Using vein rather than artery for the vessels leaving the ventricles.
• Failing to compare pressure values when deciding valve state.
• Using diameter rather than radius in the area calculation.
• Giving cardiac output in cm³ per beat or without a unit.
• Treating a correlation as proof of cause.
• Describing the heart attack without the interrupted blood flow.

Next steps

• Revision notes
• Study guide
• OxfordAQA A-level Biology hub
• Printable checklist
• All free 10-minute diagnostics
• Book a free trial class

Official syllabus

OxfordAQA International AS and A-level Biology (9610), Version 5.1, for International AS exams May/June 2017 onwards and International A-level exams May/June 2018 onwards. Published by OxfordAQA.