What you need to know
- 1.12–1.20Cardiovascular risk, evidence, dietary factors, vitamin C and treatments.
By the end, you should be able to…
- Retrieve key mechanisms before checking the answers.
- Apply ideas to unfamiliar numerical and experimental examples.
- Identify and correct missing steps in an explanation.
Build your understanding
Describe before explaining
Quote a relevant comparison with units, calculate what is requested, and distinguish an observed association from a causal explanation. A large sample alone does not remove bias.
Evaluate treatments by mechanism and trade-off
Identify what a treatment changes and why that may lower risk, then consider an appropriate adverse effect or limitation. These questions test biological reasoning, not personal treatment choices.
Make your reasoning visible
Answer the command word
Describe the pattern, explain the mechanism or evaluate the evidence as requested. A correct fact may still miss the question.
Show workings and units
Write a calculation before its result, and distinguish fractions, percentages and percentage-point changes.
Use answers diagnostically
Attempt the question first, then identify the missing step rather than only checking whether your final number matches.
Avoid this misconception
The claim: A longer answer automatically earns more credit.
The correction: Relevance, accuracy and the requested reasoning matter.
Check your understanding
Try each question before opening the suggested answer.
Check your understanding (continued)
Practice question
Retrieval and explanation · suggested answer
In fictional equal-sized groups, 12 of 200 exposed people and 4 of 200 unexposed people develop a condition. Calculate risk in each group, relative risk and absolute risk difference.
Show suggested answer
Risks are 6% and 2%. Relative risk = 6/2 = 3. Absolute difference = 4 percentage points. These figures alone do not establish causation.
Practice question
Retrieval and explanation · suggested answer
A dietary survey links a food with lower CVD risk. Give two design issues to check.
Show suggested answer
Check sample selection and size, how diet was measured, and confounders such as exercise or smoking. Also check follow-up and whether groups were comparable; any two explained issues are relevant.
Practice question
Retrieval and explanation · suggested answer
Why does an association with antioxidant-rich foods not prove that high-dose antioxidant supplements prevent CVD?
Show suggested answer
Foods contain many substances and correlate with other behaviours. Supplements differ in dose and context. Confounding and experimental supplement evidence must be considered separately.
Practice question
Retrieval and explanation · suggested answer
Contrast a statin and an anticoagulant, including one treatment trade-off.
Show suggested answer
A statin reduces cholesterol synthesis and can lower LDL. An anticoagulant reduces clot formation through the coagulation pathway. Anticoagulation can reduce thrombosis risk but increase bleeding risk; treatments require benefit–risk evaluation.
Practice question
Retrieval and explanation · suggested answer
A fictional vitamin C standard at 0.50 mg cm⁻³ requires 2.0 cm³ to decolourise a fixed DCPIP aliquot; a juice requires 5.0 cm³. Estimate juice concentration.
Show suggested answer
0.50 × 2.0/5.0 = 0.20 mg cm⁻³, assuming comparable endpoints and no interfering reducers. More juice required means lower concentration in this fixed-DCPIP method.
Take the idea further
Apply the same specification knowledge to an unfamiliar problem. Any extra assumptions are supplied in the question.
Stretch question
A headline reports a 50% risk reduction. In one setting risk falls from 20% to 10%; in another from 0.2% to 0.1%. Compare the absolute changes.
Show a hint
Subtract the risks in each setting.
Explore the reasoning
The absolute reductions are 10 percentage points and 0.1 percentage points. The same relative reduction can represent very different absolute benefits, so baseline risk matters.
Recall this lesson
Lesson recall questions
Question 1 of 5: A fair test keeps the ________ of DCPIP the same; the ________ is the volume of sample at the ________.
Vitamin C in food and drink
Practice question
Retrieval and explanation · suggested answer
A fair test keeps the ________ of DCPIP the same; the ________ is the volume of sample at the ________.
Lesson: CP2: Vitamin C Content of Food and Drink
Try this from memory first.
Put your biology to work
Explore where these ideas appear in the world. Enrichment, not extra required recall.
Why “best medicine” needs a context
1C · The Benefits and Risks of TreatmentNHLBI describes several medicine groups used in coronary heart disease, acting on different parts of the disease process. This illustrates why matching a treatment to a clinical situation…Specification 1.20Read & use the scienceClose article
Why this matters
NHLBI describes several medicine groups used in coronary heart disease, acting on different parts of the disease process. This illustrates why matching a treatment to a clinical situation requires more than knowing one mechanism. A medicine reducing platelet aggregation targets a different step from one lowering blood pressure or cholesterol. The expected benefit also depends on the person’s starting risk and the outcome being prevented. For a clinical researcher, the question is not just whether a mechanism works, but how often important benefits and harms occur in an appropriate comparison group. This makes the specification’s evaluation of benefits and risks practical: a plausible action alone cannot identify the best treatment for everyone.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 1, pp. 15–18. The application extends beyond required recall.
- 1.20 know the benefits and risks of treatments for cardiovascular disease (CVD) (antihypertensives, statins, anticoagulants and platelet inhibitors)
Use the science
Why is “this medicine prevents clots, so everyone should take it” an unjustified claim?
Explore a possible response
Baseline clot risk varies, while medicines can cause harms such as bleeding. Evidence from one patient group may not apply to everyone, and individual decisions need clinical assessment.
Explore the source
Testing a side effect without dismissing it
1C · The Benefits and Risks of TreatmentThe SAMSON trial studied people who had stopped statins because of symptoms. Participants experienced periods with statin tablets, placebo tablets and no tablets, allowing researchers to compare symptom…Specification 1.16 · 1.20Read & use the scienceClose article
Why this matters
The SAMSON trial studied people who had stopped statins because of symptoms. Participants experienced periods with statin tablets, placebo tablets and no tablets, allowing researchers to compare symptom patterns within individuals. Symptoms during placebo and statin periods were similar on average. This illustrates the nocebo effect: expectations and the experience of treatment can contribute to symptoms. The symptoms are real; the result does not mean every adverse reaction is imagined or that statins cannot cause harm. The study shows why evaluating a treatment requires a suitable comparison and attention to the population actually recruited.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 1, pp. 15–18. The application extends beyond required recall.
- 1.16 be able to evaluate the design of studies used to determine health risk factors, including sample selection and sample size used to collect data that is both valid and reliable
- 1.20 know the benefits and risks of treatments for cardiovascular disease (CVD) (antihypertensives, statins, anticoagulants and platelet inhibitors)
Use the science
What does the no-tablet period help distinguish that a statin-versus-placebo comparison alone cannot?
Explore a possible response
It helps separate background symptoms from symptoms associated with taking a tablet and treatment expectations. A placebo arm alone cannot quantify the no-tablet baseline.
Explore the source
- Side Effect Patterns in a Crossover Trial of Statin, Placebo, and No TreatmentHoward et al., Journal of the American College of Cardiology (2021)