AQA GCSE Biology 8461: Health issues, lifestyle and cancer – Study Guide

Health is the state of physical and mental well-being, and the AQA GCSE Biology (8461) specification asks you to explain how disease, lifestyle and other factors affect it, how risk factors are linked to non-communicable diseases, and what cancer is. In the exam you must also handle data: work out disease rates, read charts and scatter diagrams, and judge whether a study’s sample and evidence support its conclusion.

This guide teaches three linked sections of Topic 4.2 Organisation: 4.2.2.5 Health issues, 4.2.2.6 The effect of lifestyle on some non-communicable diseases and 4.2.2.7 Cancer (specification Version 1.0, for teaching from September 2016 and exams from 2018). All three are assessed on Paper 1 at Foundation and Higher Tier, and none of the content is marked (HT only) or (biology only), so everything here applies to every student.

For quick recall use the health and lifestyle revision notes and the cancer revision notes; then test yourself with the health, lifestyle and cancer practice questions. Coronary heart disease, the other non-communicable disease in this topic, is covered in the heart and blood vessels study guide and the coronary heart disease revision notes. The course hub is AQA GCSE Biology.

Syllabus coverage

Spec	What you must be able to do
4.2.2.5	Describe the relationship between health and disease, and the interactions between different types of disease
4.2.2.5	Translate disease incidence information between graphs and numbers; construct and interpret frequency tables and diagrams, bar charts and histograms; use a scatter diagram to identify a correlation (MS 2c, 2g, 4a)
4.2.2.5	Understand the principles of sampling as applied to scientific data, including epidemiological data (MS 2d)
4.2.2.6	Discuss the human and financial cost of non-communicable diseases to an individual, a local community, a nation or globally
4.2.2.6	Explain the effect of lifestyle factors, including diet, alcohol and smoking, on the incidence of non-communicable diseases at local, national and global levels
4.2.2.6	Interpret data about risk factors for the specified diseases (WS 1.5), including correlation from scatter diagrams
4.2.2.7	Describe cancer as the result of changes in cells that lead to uncontrolled growth and division; distinguish benign and malignant tumours; know that there are lifestyle and genetic risk factors

What is the difference between health and disease?

The specification defines health as the state of physical and mental well-being. Two things follow from that wording. First, health includes mental well-being, so an answer that only talks about the body is incomplete. Second, health is not simply “not being ill”: a person can have no diagnosed disease and still be in poor health because of stress or poor diet.

Diseases are major causes of ill health. They come in two kinds:

Type	Caused by a pathogen?	Can spread between people?	Example
Communicable	Yes (virus, bacterium, fungus or protist)	Yes	Measles, salmonella food poisoning
Non-communicable	No	No	Coronary heart disease, Type 2 diabetes, most cancers

The specification also names other factors that can have a profound effect on both physical and mental health: diet, stress and life situations. Life situations cover things such as where you live, your income and your access to healthcare. Learn these three by name; a 2-mark “give two factors” question expects them.

How can different types of disease interact?

Diseases do not happen in isolation. The specification lists four interactions, and you should be able to give each with an example.

1. Defects in the immune system make a person more likely to suffer from infectious diseases. HIV, for example, damages white blood cells, so infections that a healthy immune system would control can take hold.
2. Viruses living in cells can trigger cancers. Infection with human papillomavirus (HPV) can lead to cervical cancer, which is why the HPV vaccine is offered to young people in the UK.
3. Immune reactions first caused by a pathogen can trigger allergies, such as skin rashes and asthma.
4. Severe physical ill health can lead to depression and other mental illness.

In an “explain” question, link cause and effect: “HIV destroys white blood cells, so the body is less able to destroy pathogens, so the person is more likely to get other infections.”

How do you handle disease incidence data?

Incidence means the number of new cases of a disease in a population over a stated time. Because populations differ in size, you compare rates, not raw numbers.

rate per 100 000 people = (number of new cases / population) x 100 000

Worked example 1. Town A (population 600 000) records 1 020 new cases of a disease in a year. Town B (population 150 000) records 330.

• Town A: 1 020 / 600 000 x 100 000 = 170 per 100 000
• Town B: 330 / 150 000 x 100 000 = 220 per 100 000

Town A has more cases, but Town B has the higher rate, so a person in Town B is more likely to develop the disease.

Which chart should you draw?

Data	Chart
Separate categories, such as cases in different countries	Bar chart with gaps between bars
Continuous data grouped into classes, such as cases by age group	Histogram with no gaps
Two variables measured for each person or place	Scatter diagram
Raw counts sorted into groups	Frequency table first, then a bar chart or histogram

Worked example 2 (histogram with unequal classes). In a survey, 180 people aged 20 to under 40 had a condition. The class width is 20 years, so the bar height is frequency density = 180 / 20 = 9 people per year of age. With unequal class widths, the area of each bar, not its height, shows the frequency.

What does a scatter diagram show?

If the points rise from left to right there is a positive correlation; if they fall, a negative correlation; if they show no pattern, no correlation. A correlation shows that two variables are linked. It does not prove that one causes the other. That distinction is behind most of the marks in this section.

What are the principles of sampling for epidemiological data?

Epidemiology is the study of patterns of disease in populations. Scientists can rarely study every person, so they study a sample. A sample gives trustworthy results when it is:

• large, so that a few unusual individuals do not distort the pattern;
• representative of the population (similar ages, sexes and backgrounds);
• chosen at random, so the researchers do not bias it.

Confidence grows when other independent studies find the same pattern. When you evaluate a study, comment on each of these points using the information given in the question.

What is a risk factor?

A risk factor is something linked to an increased rate of a disease. The specification gives two kinds:

• aspects of a person’s lifestyle, such as smoking, diet, exercise and alcohol;
• substances in the person’s body or environment, such as high blood cholesterol or ionising radiation.

For some risk factors a causal mechanism has been proven, meaning scientists can explain how the factor causes the disease. For others there is a correlation but no proven mechanism yet. Many diseases are caused by the interaction of a number of factors, which is why one heavy smoker may never get lung cancer and a non-smoker may.

Which lifestyle links does AQA specify?

Risk factor	Disease or effect	How it works (at GCSE depth)
Diet, smoking and lack of exercise	Cardiovascular disease	A diet high in saturated fat raises blood cholesterol; smoking damages artery walls; both lead to fatty deposits that narrow arteries. Regular exercise lowers the risk
Obesity	Type 2 diabetes	Body cells no longer respond properly to insulin
Alcohol	Liver and brain function	Alcohol is broken down in the liver; long-term heavy drinking damages liver cells (for example cirrhosis). Alcohol also slows reactions and can damage brain tissue over time
Smoking	Lung disease and lung cancer	Tar damages the airways and alveoli and contains carcinogens
Smoking and alcohol in pregnancy	Harm to the unborn baby	Carbon monoxide in smoke reduces the oxygen the blood carries, linked to low birth weight and premature birth; alcohol crossing the placenta can damage the baby’s development, including the brain
Carcinogens, including ionising radiation	Cancer	Carcinogens damage DNA, so cells may begin to divide uncontrollably

How does lifestyle change incidence at different levels?

The incidence of non-communicable diseases follows lifestyle in a population. Locally, an area where more people smoke tends to have more lung cancer. Nationally, rising obesity has been accompanied by rising Type 2 diabetes. Globally, as diets and habits change in many lower- and middle-income countries, non-communicable diseases are becoming more common there too. When asked to “explain”, name the factor, the disease and the direction of the change.

What are the human and financial costs?

Level	Human cost	Financial cost
Individual	Pain, reduced quality of life, shorter life expectancy	Lost income; care costs
Local community	Families become carers; people leave work	Pressure on local health and care services
Nation	Fewer healthy people in work	Cost of treatment (in the UK mostly through the NHS); lost productivity
Global	Many early deaths	Large health spending; slower economic development

A “discuss” question wants both human and financial costs, at more than one level.

Worked example 3 (interpreting risk data). In a study, 45 in every 1 000 smokers and 9 in every 1 000 non-smokers developed a lung disease. 45 / 9 = 5, so smokers in this sample were 5 times as likely to develop the disease. To conclude that smoking causes it, you would also need a known mechanism (such as tar damaging the alveoli), a large representative sample, and other studies that agree.

What is cancer?

Cancer is the result of changes in cells that lead to uncontrolled growth and division. Normally, cell division by mitosis is controlled. When those controls are lost, cells keep dividing and form a mass called a tumour.

	Benign tumour	Malignant tumour
What it is	A growth of abnormal cells	Cancer cells
Where it stays	Contained in one area, usually within a membrane	Invades neighbouring tissues
Does it spread?	No, it does not invade other parts of the body	Yes: cells break off and travel in the blood to other parts of the body
What forms elsewhere	Nothing	Secondary tumours

A benign tumour can still be harmful if it presses on an organ, but it is not cancer. The word to remember for malignant tumours is spread: they invade, travel in the blood and form secondary tumours.

What causes cancer?

Scientists have identified lifestyle risk factors for various types of cancer: for example, smoking and lung cancer, and exposure to carcinogens and ionising radiation (such as X-rays and gamma rays) more generally. There are also genetic risk factors for some cancers: some people inherit gene variants that raise their risk (for example, inherited faulty BRCA1 or BRCA2 genes raise the risk of breast cancer). The link to 4.2.2.5 is also examinable: viruses living in cells, such as HPV, can trigger cancer.

Frequently asked questions

Is a risk factor the same as a cause? No. A risk factor is linked to an increased rate of a disease. It becomes a cause only when a causal mechanism has been shown, and even then it does not guarantee that a particular person will get the disease.

Why do studies compare rates rather than numbers of cases? Because populations are different sizes. A rate per 100 000 people puts every population on the same scale, so you can see where a person is genuinely more likely to become ill.

Can a benign tumour turn into cancer? The specification only asks you to distinguish benign tumours (contained, not invading) from malignant tumours (invading and spreading in the blood to form secondary tumours). Answer exam questions with those definitions.

Is Type 2 diabetes a communicable disease? No. It is non-communicable: it is not caused by a pathogen and cannot be passed from person to person. Obesity is the risk factor the specification names.

Does a scatter diagram showing a correlation prove the link? No. It shows the two variables change together. Other factors could explain the pattern, so you need a mechanism and repeated, well-sampled studies before claiming cause.

Common mistakes

• Writing that smoking “causes” a disease when the data only shows a correlation; say it increases the risk or rate unless the question gives a mechanism.
• Leaving mental well-being out of the definition of health.
• Comparing raw numbers of cases between populations of different sizes.
• Saying malignant tumours spread “through the body” without saying in the blood and naming secondary tumours.
• Describing a benign tumour as “harmless” or “not made of abnormal cells”.
• Describing a trend on a graph without quoting any figures.

Official syllabus

AQA GCSE Biology (8461) specification, Version 1.0 (21 April 2016), for teaching from September 2016 and exams from 2018 onwards, Topic 4.2 Organisation: 4.2.2.5 Health issues, 4.2.2.6 The effect of lifestyle on some non-communicable diseases, and 4.2.2.7 Cancer, with the mathematical skills MS 2c, 2d, 2g and 4a.