Most of us feel ill sometimes. Some illnesses spread, like a cold. Others do not spread at all, like asthma. Knowing the difference helps scientists, doctors and you to make good choices.
This matters because many diseases are linked to how we live. Smoking, diet and exercise all change the chance of getting ill. You also need to judge health news carefully.
By the end you will be able to sort diseases into two types and explain what a risk factor is. You will tell a correlation from a cause. You will describe how heart disease is treated.
Health and two types of disease
Health is a state of physical and mental wellbeing. Many things affect it, including diet, stress and the situation a person lives in.
A communicable disease is caused by a pathogen and can spread from one person to another. A pathogen is a microorganism that causes disease, such as a virus or a bacterium.
A non-communicable disease cannot be passed on. Examples are heart disease, cancer, diabetes and asthma. You cannot catch them from someone else.
How diseases interact
One disease can make another more likely. A weak immune system means the body fights infections less well. So there are more infectious diseases.
A virus that infects cells can trigger cancer. The human papillomavirus does this in cervical cancer. Immune reactions to a pathogen can also cause allergies, such as skin rashes and asthma.
Serious physical ill health can lead to depression and other mental illness. So doctors look at the whole person, not just one illness.
Risk factors
A risk factor is something linked to a higher chance of getting a disease. Some risk factors are lifestyle choices, such as smoking, alcohol, diet and lack of exercise.
Others are not choices. They include the genes you inherit and exposure to radiation or pollution.
A risk factor does not guarantee a disease. Think of not wearing a seatbelt. It raises your chance of injury, but you may never be hurt. Someone without a risk factor can still become ill.
Linking risk factors to diseases
Smoking causes lung disease, lung cancer and cardiovascular disease. Cardiovascular means to do with the heart and blood vessels. Obesity is a risk factor for type 2 diabetes.
Alcohol can damage the liver and brain. Drinking in pregnancy can harm the unborn baby, and smoking in pregnancy can cause a low birth mass.
A carcinogen is something that can cause cancer, such as ionising radiation or ultraviolet light. A diet short of a nutrient causes a deficiency disease, such as scurvy from too little vitamin C.
Correlation and cause
A correlation is a link between two things. A cause means one thing makes the other happen. A correlation does not prove a cause.
Think of ice cream sales and sunburn. Both rise in summer, but ice cream does not cause sunburn. The sun causes both.
For smoking and lung cancer, scientists first found a correlation. Then they found chemicals in smoke that cause cancer. That is how a cause was shown. When judging data, ask if the sample is large, representative and well controlled.
Treating cardiovascular disease
In coronary heart disease, fatty deposits block the coronary arteries, which feed the heart muscle. Think of a drain blocked with fat. Statins are drugs that lower blood cholesterol. A stent is a small tube that keeps an artery open.
Damaged heart valves can be replaced with biological or mechanical valves. In heart failure, a donor heart can be transplanted, or an artificial heart can be used for a while.
Each treatment has costs and risks. Statins must be taken for life. Surgery can cause infection, and a transplanted heart can be rejected.
Recap
Communicable diseases are caused by pathogens and spread. Non-communicable diseases do not.
A risk factor raises the chance of a disease. It does not guarantee it.
A correlation is a link. It does not prove a cause.
Heart disease can be treated with statins, stents, valve replacement and transplants.
Key points
Communicable diseases are caused by pathogens. Non-communicable diseases are not.
A risk factor raises the chance of disease but does not always cause it.
A correlation does not prove a cause.
Treatments for heart disease: statins, stents, valve replacement and transplant.
Worked examples
Example 1
State what is meant by a communicable disease.
Communicable diseases are caused by pathogens.
They can pass from one person to another.
So a communicable disease is one that can spread.
Answer: a disease caused by a pathogen that can spread between people
Common slips
Slip: a disease passed on in genes This describes an inherited disease. Communicable diseases are caused by pathogens.
Slip: a disease caused by diet Diet-related diseases are not communicable.
Slip: a disease that cannot spread This is a non-communicable disease.
Example 2
A study finds that people who eat a lot of fried food are more likely to have heart disease. A newspaper says fried food causes heart disease. Explain why this may not be true.
The study shows a correlation.
A correlation does not prove a cause.
Other factors, such as exercise or smoking, may also differ between the groups.
Answer: It is a correlation, which does not prove a cause, as other factors may be involved
Common slips
Slip: The study must be wrong. The correlation may be real. It does not show that one thing causes the other.
Slip: Fried food is healthy. The point is that correlation is not proof.
Slip: Only a large sample matters. Other factors also need to be controlled.
Example 3
Give one advantage and one disadvantage of taking statins to reduce the risk of coronary heart disease.
Statins reduce cholesterol, which reduces the build-up of fatty deposits in arteries.
This lowers the risk of a heart attack.
A disadvantage is that statins must be taken for a long time and can have side effects.
Answer: Advantage: they lower cholesterol and reduce the risk of heart attack. Disadvantage: they must be taken for years and can cause side effects
Common slips
Slip: They cure heart disease completely. Statins reduce risk, but they do not cure the disease.
Slip: They are made of cholesterol. They lower cholesterol.
Slip: They stop the heart beating. This is not a side effect we consider here.
Questions and answers
Health, disease and risk factors practice questions for GCSE Combined Science Biology. Try each one, then open the answer. Easy questions come first.
Question 1 Easy
Name a non-communicable disease that is linked to smoking.
Show answer
Answer: lung cancer
Smoke contains harmful chemicals.
It causes lung cancer.
Question 2 Easy
What do we call something that increases the chance of getting a disease?
Show answer
Answer: risk factor
It raises the chance.
It is a risk factor.
Question 3 Easy
What type of drug lowers blood cholesterol?
Show answer
Answer: statins
Cholesterol builds up in arteries.
Statins lower it.
Question 4 Easy
What is put into an artery to keep it open?
Show answer
Answer: stent
A small tube props the artery open.
It is a stent.
Question 5 Easy
What name is given to a microorganism that causes disease?
Show answer
Answer: pathogen
It is a germ that makes you ill.
It is called a pathogen.
Question 6 Easy
Is asthma a communicable or a non-communicable disease?
Show answer
Answer: non-communicable
Asthma is not caused by a pathogen.
So it is non-communicable.
Question 7 Medium
Name the type of diabetes linked to obesity.
Show answer
Answer: type 2
Obesity raises the risk.
It is type 2.
Question 8 Medium
Name the disease caused by a lack of vitamin C.
Show answer
Answer: scurvy
A lack of a nutrient is a deficiency disease.
Vitamin C deficiency is scurvy.
Exam-style questions
Longer questions in the style of a written paper, with the marking points. These are Yumio practice questions.
Exam-style question 14 marks
(a) State one lifestyle risk factor for cardiovascular disease. [1 mark] (b) A study finds that smokers get more heart disease. Explain why this does not prove smoking is the cause. [2 marks] (c) Name one treatment for coronary heart disease. [1 mark]
Show answer and marking points
Answer: (a) smoking, poor diet or lack of exercise (b) it is a correlation, and other factors might differ between the groups (c) statins, a stent or a valve replacement
(a) smoking, poor diet, or lack of exercise (1)
(b) a correlation does not prove a cause (1)
(b) other factors may explain the difference (1)
(c) statins, stent, valve replacement or transplant (1)
Exam-style question 26 marks
A man has a high level of cholesterol and a narrowed coronary artery. Discuss the treatments and lifestyle changes that could reduce his risk of a heart attack. [6 marks]
Show answer and marking points
Answer: Statins reduce blood cholesterol and slow fatty deposits, but must be taken for life and can have side effects. A stent keeps the artery open and restores blood flow, but surgery carries a risk of infection and the stent can become blocked again. Lifestyle changes such as stopping smoking, eating less saturated fat, losing weight and exercising lower the risk with no side effects, but they need long-term commitment. A combination gives the best result.
Level 1 (1 to 2 marks): names one or two treatments or lifestyle changes with little or no explanation (2)
Level 2 (3 to 4 marks): explains how at least two of statins, a stent and lifestyle changes reduce the risk, with an advantage or disadvantage of at least one (2)
Level 3 (5 to 6 marks): explains all three approaches with advantages and disadvantages for each and makes a reasoned overall judgement (2)
Common mistakes
Saying a correlation proves one thing causes another
A correlation is a link. A cause needs a mechanism or a controlled experiment.
Saying every smoker will get cancer
A risk factor raises the chance. It does not guarantee the disease.
Saying cancer is communicable
Cancer is not caused by a pathogen and cannot be passed from person to person.
Saying statins widen the arteries
Statins lower cholesterol. A stent holds an artery open.
Questions students ask
Is Health, disease and risk factors on the Foundation or Higher tier?
Health, disease and risk factors is on both Foundation and Higher papers for GCSE Combined Science Biology, aimed at around grade 5.
What is a common mistake on Health, disease and risk factors?
Saying a correlation proves one thing causes another. A correlation is a link. A cause needs a mechanism or a controlled experiment.
Where are the answers to the Health, disease and risk factors questions?
Open Show answer under each question on this page. The questions are Yumio practice questions, not past exam questions.