Explain why a study of a risk factor should include a very large number of people.

Small samples are easily distorted by chance, so a large sample gives a more reliable estimate of the real effect.

Why should a study of a risk factor also include people who are not exposed to it?

Those people show what the rate of disease would be without the factor, so the two groups can be compared.

Suggest why a survey carried out in one workplace may give misleading data about a risk factor nationally.

The sample is not representative, because the people share an age range, income and way of life unlike the wider population.

AQA GCSE Combined Science Biology 8464

Bioenergetics

Topic overview The photosynthesis reaction and the uses of glucose Rate of photosynthesis Why organisms respire, and aerobic versus anaerobic The equations for respiration, and fermentation Response to exercise Metabolism

Cell Biology

Topic overview Eukaryotes and prokaryotes Animal and plant cells Cell specialisation and differentiation Microscopy Chromosomes, mitosis and the cell cycle Stem cells in embryos, adults and meristems Therapeutic cloning, its risks, and cloning plants Diffusion and the factors affecting its rate Surface area to volume ratio and exchange surfaces Osmosis Active transport

Ecology

Topic overview Levels of organisation in an ecosystem, and what organisms need Competition, interdependence and stable communities Abiotic factors Biotic factors Adaptations Producers, food chains and sampling with quadrats and transects Predators, prey and measuring population size How materials are cycled Waste management and biodiversity Land use, deforestation and global warming Maintaining biodiversity

Homeostasis and Response

Topic overview Homeostasis The nervous system and the reflex arc Human endocrine system Insulin, glucagon and diabetes Hormones in human reproduction Contraception The use of hormones to treat infertility Negative feedback

Infection and Response

Topic overview Communicable (infectious) diseases Viral diseases Bacterial diseases Fungal and protist diseases Human defence systems Vaccination Antibiotics and painkillers Discovery and development of drugs

Inheritance, Variation and Evolution

Topic overview Sexual and asexual reproduction Meiosis DNA and the genome Genetic terms, dominant and recessive alleles Punnett squares, probability and genetic crosses Inherited disorders and sex determination Variation Evolution Selective breeding What genetic engineering is, and what it is used for GM crops, their risks, and the steps of the process Evidence for evolution, and extinction Fossils Resistant bacteria Classification of living organisms

Organisation

Topic overview Levels of organisation, and how enzymes work Amylase, proteases and lipases Bile, food tests and the effect of pH on amylase The heart, the lungs and double circulation The pacemaker, the blood vessels and the blood Coronary heart disease: a non-communicable disease Health issues Risk factors and causal mechanisms in disease Sampling, correlation and interpreting risk data Cancer Plant tissues, and transpiration and its rate Root hair cells, xylem, phloem and stomata

Organisation

Sampling, correlation and interpreting risk data

3 things to know
Biology Paper 1

Overview

Why several factors interact to cause disease, large and representative samples with a comparison group, incidence and trend calculations, and correlation on a scatter diagram against a causal mechanism.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain why two people exposed to the same risk factor may not both develop the disease.

Key term

Give an example of several factors interacting to cause one disease.

Key term

Explain why it is difficult to prove that one particular factor causes a disease.

Questions from this subtopic

Each one with the model answer underneath.

1
Explain why two people exposed to the same risk factor may not both develop the disease.
Model answer
Most diseases result from several factors interacting, including inherited ones, so a single risk factor does not decide the outcome.
2
Give an example of several factors interacting to cause one disease.
Model answer
Cardiovascular disease can result from diet, lack of exercise, smoking and inherited factors acting together.
3
Explain why it is difficult to prove that one particular factor causes a disease.
Model answer
Several factors act at the same time, so the effect of the one being studied has to be separated from the rest.
4
Explain why a study of a risk factor should include a very large number of people.
Model answer
Small samples are easily distorted by chance, so a large sample gives a more reliable estimate of the real effect.
5
Why should a study of a risk factor also include people who are not exposed to it?
Model answer
Those people show what the rate of disease would be without the factor, so the two groups can be compared.
6
Suggest why a survey carried out in one workplace may give misleading data about a risk factor nationally.
Model answer
The sample is not representative, because the people share an age range, income and way of life unlike the wider population.

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AA rise is corrected by insulin.

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Habitat means the place in which an organism lives.

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