6.3.8Global Challenges

Non-Communicable Human Diseases — OCR Gateway GCSE Combined Science A J250 - Biology Revision Notes & Topical Questions

5 min read 9 parts Lesson 16 of 18

📚 OCR Gateway GCSE Combined Science A J250 - Biology Hub / Topical Revision

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Part 1 of 7Multiple risk factors

Non-communicable diseases are often caused by several factors acting together: genetic make-up, diet, lifestyle, age and the environment. They are the main cause of death in developed countries. This lesson covers common examples and the ways their risk can be reduced.

Part 2 of 7Cardiovascular disease

Cardiovascular diseases affect the heart and blood vessels.

Plaque

In coronary heart disease, the coronary arteries that supply the heart muscle become narrowed by layers of fatty material, called plaque, containing cholesterol.

Narrowed vessels allow less blood and so less oxygen to reach the heart muscle; if a clot blocks a coronary artery, part of the muscle dies,

causing a heart attack.

Risk factors include a diet high in saturated fat and salt, smoking, lack of exercise, high blood pressure, obesity and genetics. Treatments:

Statins

Statins reduce blood cholesterol.

Stents

Stents are small mesh tubes placed in an artery to hold it open.

Bypass surgery

Bypass surgery uses a vein from the leg to carry blood around a blocked artery.

Artificial valves

Artificial valves or hearts, and transplants, for failing hearts.

Drugs and surgery have limits (statins must be taken long-term and can have side effects; operations carry risks), so preventing the disease through a healthy lifestyle is more cost-effective.

Part 3 of 7Smoking and alcohol

Tobacco smoke contains nicotine (addictive), tar (contains carcinogens and damages the lungs), carbon monoxide (binds irreversibly to haemoglobin, reducing oxygen transport) and many other toxic chemicals. Smoking increases the risk of lung cancer, chronic obstructive pulmonary disease, heart disease and strokes. Smoking in pregnancy leads to lower birth weight and increases the risk of premature birth.

Alcohol is broken down in the liver. Excess alcohol can cause liver disease (cirrhosis), damages the brain, affects judgement and reaction time, and increases the risk of some cancers. Drinking during pregnancy can harm the baby's development (foetal alcohol syndrome).

Part 4 of 7Obesity and type 2 diabetes

People are obese when their body mass index is over 30. BMI = mass (kg) / height (m) squared. For example, a person of 90 kg and 1.70 m has BMI = 90 / (1.70 x 1.70) = 90 / 2.89 = 31.1, so is obese.

Obesity and type 2 diabetes

BMI is a guide, and does not distinguish muscle from fat, so waist-to-hip ratio is sometimes used as well.

Obesity is caused by an energy intake higher than expenditure, and sometimes genetic factors.

It raises the risk of type 2 diabetes, high blood pressure, heart disease, joint problems and some cancers.

In type 2 diabetes body cells no longer respond properly to insulin, or too little is made, so blood glucose stays high.

Obesity and type 2 diabetes

Control is by a diet low in sugar and refined carbohydrates, regular exercise, weight loss, and in some cases drugs or insulin.

Type 1 diabetes, by contrast, is caused by the immune system destroying insulin-producing cells and is treated with insulin injections.

Part 5 of 7Interpreting data on risk

Data may show that a risk factor and a disease are correlated.

State the trend with numbers: 'smokers are 15 times more likely to die of lung cancer than non-smokers'.

Comment on the sample (large, representative, over many years) and note that studies have used laboratory evidence to show a mechanism,

which strengthens the case.

Be careful of confusing percentages with actual numbers, and of conclusions that go beyond the data.

Also remember that lifestyle choices are affected by income, education, advertising and availability,

so public health measures include taxes on tobacco and sugary drinks, labelling, and education campaigns.

Part 6 of 7Prevention and screening

Preventing disease is often more effective than treating it.

A balanced diet low in saturated fat and salt, at least 150 minutes a week of moderate exercise, not smoking and drinking within the recommended limits all lower the risk of cardiovascular disease, type 2 diabetes and several cancers.

Screening programmes, such as mammography for breast cancer and cervical screening, find disease early.

Screening has costs and limits: false positives cause worry and unnecessary tests, and false negatives give false reassurance.

The government may also fund campaigns and regulations because the cost of treating disease falls on the whole society.

Alcohol units provide a way of tracking intake, and the guidance is to spread drinking over several days and to have alcohol-free days,

because the liver needs time to recover and repair itself.

Part 7 of 7Exam-style questions

A man has mass 105 kg and height 1.80 m. Calculate his BMI and state whether he is obese. [3]3 marks
Explain how a high-fat diet can lead to a heart attack. [4]4 marks
Describe how carbon monoxide in cigarette smoke affects the body. [2]2 marks

Key terms

Term	Meaning
Cardiovascular disease	A disease of the heart or blood vessels.
Plaque	A fatty deposit in an artery wall.
Statin	A drug that lowers blood cholesterol.
Stent	A mesh tube placed in an artery to keep it open.
Carcinogen	A substance that can cause cancer.
Body mass index (BMI)	Mass in kg divided by height in metres squared.
Type 2 diabetes	A condition in which cells respond poorly to insulin.
Risk factor	A factor that increases the chance of developing a disease.

Avoid these mistakes

Giving nicotine as the cause of lung cancer; carcinogens in tar cause cancer, while nicotine is addictive.

Mixing up the formula for BMI by not squaring the height.

Saying that diabetes is caused by eating sugar alone.

Writing that statins remove blockages immediately; they lower cholesterol over time.

Claiming that correlation of a risk factor and disease means every smoker will get the disease.

Last updated: 20 October 2026