May/June 2026 Paper 53

2026 · 2 questions · 12 parts · 30 marks

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1(a)(i)1(a)(ii)1(a)(iii)1(b)(i)1(b)(ii)1(b)(iii)

–/19 mks

2(a)2(b)2(c)(i)2(c)(ii)2(c)(iii)2(d)

–/11 mks

Context for question 2

Approximately 50% of cases of coronary heart disease are thought to be a result of high blood pressure. Approximately 25% of adults worldwide have high blood pressure. Blood pressure changes during the cardiac cycle, so the measurement of blood pressure uses two values: systolic blood pressure and diastolic blood pressure. A person who is described as having high blood pressure will have a resting systolic blood pressure of

140 mmHg

or higher and a resting diastolic blood pressure of

90 mmHg

or higher. There is some evidence that eating garlic can have positive effects on human health, including benefits to the cardiovascular system. The storage organ (bulb) of the garlic plant, Allium sativum, is eaten worldwide. Figure 2.1 shows a garlic bulb.

Figure 2.1, a photograph of a garlic bulb (Allium sativum) showing its papery outer skin and cluster of cloves

Garlic extract can be obtained from garlic bulbs and placed into capsules that can be swallowed. Scientists investigated the effect of eating garlic capsules on the blood pressure of people that had been diagnosed with high blood pressure. The investigation studied 84 men and women of various ages. Each person was randomly placed in one of four groups and asked to follow a specific treatment for 12 weeks.

21 people ate one garlic capsule each day.
21 people ate two garlic capsules each day.
21 people ate four garlic capsules each day.
21 people were placed in a control group.

All the people continued taking any medication for high blood pressure that they had previously been prescribed. The resting systolic blood pressure of each person was measured at the start of the investigation and at intervals during the 12 weeks.

2(a)Experimental DesignEasy2 marks

Identify the independent variable and the dependent variable in this investigation.

Independent variable

Dependent variable

2(b)Experimental DesignEasy1 mark

Suggest a suitable treatment for the people in the control group.

Answer

0 words

Context for 2(c)

The results for the blood pressure measurements are shown in Table 2.1. The standard errors (SE) for each value are shown in brackets.

Table 2.1: mean resting systolic blood pressure / mmHg (

\pm

SE)

number of weeks after the start of the investigation	control group	1 garlic capsule each day	2 garlic capsules each day	4 garlic capsules each day
0	$148.8 \pm 2.8$	$148.7 \pm 2.8$	$149.3 \pm 2.6$	$149.4 \pm 2.7$
4	$142.8 \pm 2.9$	$137.7 \pm 2.8$	$144.5 \pm 2.7$	$138.3 \pm 2.7$
8	$140.0 \pm 2.9$	$135.2 \pm 2.8$	$131.4 \pm 2.6$	$132.6 \pm 2.9$
12	$138.1 \pm 3.1$	$138.8 \pm 3.1$	$126.8 \pm 2.8$	$132.4 \pm 3.0$

2(c)(i)Tables GraphsEasy1 mark

Resting systolic blood pressure is a quantitative variable. State the type of data represented by the resting systolic blood pressure.

2(c)(ii)Interpreting Data Drawing ConclusionsMedium3 marks

Outline the conclusions that can be made from the data in Table 2.1.

Answer

0 words

2(c)(iii)Statistical Tests BiologyHard2 marks

The scientists decided that the t-test was not an appropriate choice of statistical test for the investigation. Suggest two reasons why the t-test is not an appropriate choice of statistical test for the investigation.

Answer

0 words

2(d)Evaluation UncertaintyMedium2 marks

Suggest two changes that could be made to the investigation method that may increase confidence in the conclusions.

Answer

0 words