Health & Disease (AQA GCSE Biology): Revision Notes
Lifestyle and disease
Exercise and disease
Obesity means being very overweight. This is a major lifestyle risk factor for type 2 diabetes.
When people exercise regularly, they find it easier to control their body weight. This makes them less likely to develop cardiovascular disease (problems with the heart and blood vessels).
Regular exercise is one of the most effective ways to prevent lifestyle-related diseases. It helps maintain a healthy weight, which is crucial for preventing type 2 diabetes and heart problems.
Benefits of exercise:
- Better weight control
- Better overall health
- Lower risk of serious diseases
Inherited factors
Some factors that affect our health come from our genes, not our lifestyle choices. These are called inherited factors.
For example, some people inherit genes that make their blood cholesterol levels higher. Even if they eat the same healthy diet as someone else, they might still have higher cholesterol.
Why this matters for scientists: When studying lifestyle and disease, scientists must compare people with similar inherited factors. This makes sure their results are valid and reliable.
Risk factors and disease
Many diseases happen because different factors work together. Scientists need to prove that a risk factor actually causes a disease.
How scientists prove causation:
- They show the risk factor leads to the disease
- They work out exactly how this happens (the mechanism)
Examples of proven risk factors for cancer:
- Carcinogens - toxic substances that damage cells
- Exposure to ionising radiation
Scientists have found both lifestyle and genetic risk factors for different cancers.
Cancer
Cancer happens when cells change and grow in an uncontrolled way.
Types of tumours
1. Benign tumours:
- Made of abnormal cells
- Stay in one place inside a membrane
- Do not spread to other parts of the body
- Not cancerous
2. Malignant tumours:
- These are cancers
- Invade nearby tissues
- Spread through the blood to other body parts
- Form secondary tumours in new locations
Understanding scientific studies
Scientists often use control groups to test their ideas properly.
Study Example: Preventing Diabetes Through Lifestyle Changes
- 522 overweight people at risk of diabetes were split into two groups
- Group A got healthy lifestyle advice
- Group B got no advice
- After four years: 11% of Group A developed diabetes, 23% of Group B developed diabetes
- Conclusion: Healthy lifestyle advice reduces diabetes risk
What makes studies reliable:
- Using many people in the study
- Having proper control groups
- Starting with people who have similar characteristics
Key Points to Remember:
- Exercise helps prevent disease - it controls weight and improves health
- Inherited factors affect disease risk but we cannot control them
- Benign tumours stay in one place, malignant tumours (cancers) spread around the body
- Scientists need control groups to prove that lifestyle factors cause disease
- Multiple factors usually work together to cause disease, not just one thing