AQA GCSE Biology 8461: Health issues; lifestyle and non-communicable diseases – Revision Notes

These are condensed recall notes for 4.2.2.5 Health issues and 4.2.2.6 The effect of lifestyle on some non-communicable diseases of the AQA GCSE Biology (8461) specification, Version 1.0, for teaching from September 2016 and exams from 2018 onwards. Both are assessed on Paper 1, set at Foundation and Higher Tier. Nothing in these two subtopics is marked (HT only) or (biology only), so every line applies to both tiers. There is no required practical, but both subtopics expect you to handle data: incidence figures, charts, scatter diagrams and the principles of sampling.

Related notes: Coronary heart disease, Cancer, and communicable diseases in the Infection and response revision notes. Type 2 diabetes is explained further in the Homeostasis and response revision notes. The course hub is AQA GCSE Biology, and the printable checklist lists every point. To find your weak spots fast, try the free 10-minute diagnostics.

4.2.2.5 Health and disease

• Health is the state of physical and mental well-being. It is more than just not having a disease.
• Diseases are major causes of ill health. They are:
  • communicable: caused by a pathogen and can spread between people (for example measles);
  • non-communicable: not caused by a pathogen and cannot spread (for example coronary heart disease).
• Other factors can strongly affect physical and mental health: diet, stress and life situations (such as income, housing, work and access to healthcare).

How different types of disease interact

Interaction	Example
Defects in the immune system make infectious diseases more likely	HIV damages the immune system, so other infections take hold more easily
Viruses living in cells can trigger cancers	Infection with HPV can lead to cervical cancer
An immune reaction first caused by a pathogen can trigger allergies	Skin rashes and asthma
Severe physical ill health can lead to mental illness	Depression after a long or serious illness

A person can have several conditions at once, and one can make another more likely.

Handling disease data

Incidence

Incidence is the number of new cases of a disease in a population over a given time. Rates let you compare populations of different sizes.

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

Worked reminder. A town of 250 000 people has 340 new cases in a year. Rate = 340 / 250 000 x 100 000 = 136 per 100 000 per year.

Which chart?

Data	Chart
Categories (for example cases in different countries)	Bar chart, with gaps between bars
Continuous data in classes (for example cases by age group)	Histogram, with no gaps between bars
Two variables measured on the same people or places	Scatter diagram
Counts in groups	Frequency table, then a bar chart or histogram

In a histogram with unequal class widths, the bar height is frequency density = frequency / class width, so the area of each bar shows the frequency.

Correlation from a scatter diagram

Pattern	Meaning
Points rise from left to right	Positive correlation
Points fall from left to right	Negative correlation
No pattern	No correlation

A correlation shows the variables are linked. It does not on its own prove that one causes the other.

Principles of sampling (epidemiological data)

• Studying a whole population is rarely possible, so scientists study a sample.
• The sample should be large, so that chance results matter less.
• It should be representative (similar ages, sexes, backgrounds to the population) and chosen at random, so the results are not biased.
• Results are more trustworthy when other studies repeat them and find the same pattern.

4.2.2.6 Risk factors

A risk factor is linked to an increased rate of a disease. Risk factors can be:

• aspects of a person’s lifestyle (for example smoking, diet, exercise, alcohol);
• substances in the person’s body or environment (for example cholesterol in the blood, or radon gas).

For some risk factors a causal mechanism has been proven (scientists know how the factor causes the disease): for example, chemicals in tobacco smoke damage the DNA in lung cells, leading to lung cancer. For others there is only a correlation so far.

Many diseases are caused by the interaction of several factors, so one person with a risk factor may never get the disease, while another without it might.

The specified links

Risk factor	Disease or effect	Brief mechanism
Diet high in saturated fat, smoking, lack of exercise	Cardiovascular disease	Raised blood cholesterol and damage to artery walls lead to fatty deposits; regular exercise lowers the risk
Obesity	Type 2 diabetes	Body cells stop responding properly to insulin
Alcohol	Liver damage and reduced brain function	Alcohol is toxic: it damages liver cells (cirrhosis) and slows the brain; long-term use can damage brain tissue
Smoking	Lung disease and lung cancer	Tar damages the airways and alveoli (for example bronchitis and emphysema) and contains carcinogens
Smoking and alcohol in pregnancy	Harm to the unborn baby	Smoking: carbon monoxide cuts the oxygen the blood carries, linked to low birth weight and premature birth. Alcohol: can damage the baby’s development, including the brain
Carcinogens, including ionising radiation	Cancer	Damage DNA, so cells may divide uncontrollably. Ionising radiation includes X-rays and gamma rays

Lifestyle at local, national and global levels

The incidence of non-communicable diseases changes with lifestyle in a place. For example, an area where more people smoke has more lung cancer, and rising obesity in a country brings more Type 2 diabetes. As diets and habits change around the world, these diseases are becoming more common in many lower-income countries too.

Human and financial costs

Level	Human cost	Financial cost
Individual	Pain, worse quality of life, shorter life	Lost earnings; possibly care costs
Local community	Families care for relatives; people leave work	Pressure on local health and care services
Nation	Fewer healthy workers	Cost of treatment (in the UK, mainly to the NHS); lost productivity
Global	Millions of early deaths	Huge treatment costs; slower economic development

Method in steps: interpreting risk-factor data

1. Read the axes, units and the size of the sample.
2. Describe the trend, quoting numbers from the graph or table.
3. Compare groups with a calculation (difference, or "how many times more likely").
4. Say whether it is a correlation; do not claim cause unless a mechanism is given.
5. Comment on the data: sample size, representative sampling, other factors that were not controlled.

Worked reminder. In a study, 24 in every 1000 smokers and 3 in every 1000 non-smokers developed a disease. 24 / 3 = 8, so smokers in this sample were 8 times as likely to develop it. That is a strong correlation; a causal link needs a known mechanism and repeated studies.

Must-know distinctions

• Health vs disease: health is physical and mental well-being; disease is one major cause of ill health.
• Communicable vs non-communicable: caused by a pathogen and can spread vs cannot spread.
• Correlation vs causation: linked vs one proven to cause the other through a mechanism.
• Risk factor vs cause: a risk factor raises the rate of a disease; it does not guarantee it.
• Bar chart vs histogram: categories with gaps vs continuous classes with no gaps.

Quick self-test

1. Define health.
2. Give the three “other factors” the specification lists that affect physical and mental health.
3. Give two examples of how different types of disease interact.
4. What is a risk factor? Give the two kinds.
5. Name the risk factor linked to Type 2 diabetes.
6. Give two effects of alcohol named in the specification.
7. How does smoking in pregnancy harm the unborn baby?
8. A scatter diagram shows that countries with higher sugar intake have more Type 2 diabetes. Does this prove sugar causes diabetes? Explain.
9. Give two features of a good sample for a study of a risk factor.
10. A city of 400 000 people has 1200 new cases of a disease in a year. Calculate the rate per 100 000.
11. Give one human cost and one financial cost of a non-communicable disease to a nation.

Answers

1. The state of physical and mental well-being.
2. Diet, stress and life situations.
3. Any two: immune defects make infectious disease more likely; viruses can trigger cancers; immune reactions to a pathogen can trigger allergies such as rashes and asthma; severe physical ill health can lead to depression.
4. Something linked to an increased rate of a disease. Aspects of lifestyle; substances in the body or environment.
5. Obesity.
6. Damage to the liver; reduced brain function.
7. Carbon monoxide reduces the oxygen carried by the mother’s blood, linked to low birth weight and premature birth.
8. No. It shows a correlation. Other factors (such as obesity or exercise) may explain it, and a causal mechanism is needed.
9. Any two: large; representative of the population; chosen at random.
10. 1200 / 400 000 x 100 000 = 300 per 100 000.
11. Human: early deaths or fewer healthy people able to work. Financial: cost of treatment to the health service, or lost productivity.

Where marks are usually lost

• Writing that a risk factor “causes” a disease. It increases the rate (or risk).
• Concluding causation from a scatter diagram alone.
• Describing a trend without quoting any figures from the data.
• Comparing raw case numbers from populations of different sizes instead of rates.
• Forgetting that health includes mental well-being.
• Mixing up communicable and non-communicable examples.
• Drawing gaps between the bars of a histogram.

Frequently asked questions

What is health in AQA GCSE Biology? Health is the state of physical and mental well-being, not just the absence of disease.

What is a risk factor? A risk factor is linked to an increased rate of a disease. Risk factors can be aspects of lifestyle or substances in the body or environment. A risk factor does not on its own prove cause.

How do you calculate incidence per 100 000 people? Divide the number of new cases by the population and multiply by 100 000. For example, 340 cases in 250 000 people is 136 per 100 000.

What makes a sample good for epidemiological data? The sample should be large and representative of the population, and the results should be repeated by other studies.

Does a correlation prove that a risk factor causes disease? No. A correlation shows the variables are linked. A causal mechanism must be shown before a factor can be said to cause a disease.

Official syllabus

AQA GCSE Biology (8461) specification, Version 1.0, for teaching from September 2016 and exams from 2018 onwards (AQA), section 4.2 Organisation: 4.2.2.5 Health issues and 4.2.2.6 The effect of lifestyle on some non-communicable diseases.