How are figures on illness and death used to work out what raises a person's risk?

By comparing rates between different populations or groups exposed to different factors, allowing identification of factors associated with increased or decreased risk.

Why is a plausible biological mechanism important when distinguishing correlation from causation?

A plausible biological mechanism provides an explanation for how one factor could directly produce the observed effect, supporting a causal rather than coincidental relationship.

How does consistency across different studies help distinguish causation from correlation?

If the same relationship is found consistently across multiple independent studies with different populations and methods, this strengthens evidence that the relationship is causal rather than due to chance or specific study conditions.

Why is controlling confounding variables necessary when establishing causation?

Controlling confounding variables ensures that any observed relationship is due to the factor being studied rather than other variables that might influence both the factor and the outcome.

Edexcel A-Level Biology A 9BN0

Lifestyle, Health and Risk

Topic overview Water and the carbohydrates Condensation, hydrolysis and glycosidic bonds Lipids, food tests and units The cardiac cycle and the structure of the heart Arteries, veins and capillaries Core practical: caffeine and the heart rate of Daphnia The blood clotting cascade Thrombus, embolus and their consequences Atherosclerosis and the risk factors for CVD Treatments for CVD, and cholesterol transport BMI, waist-to-hip ratio and energy balance Core practical 2: the vitamin C content of food and drink Correlation, causation and the design of health studies Risk perception, and handling quantitative data

Genes and Health

Topic overview Gas exchange surfaces and Fick's Law The fluid mosaic model of the cell membrane Osmosis, diffusion and active transport Surface area and volume calculations The structure of DNA and RNA Transcription Translation and the genetic code Amino acids and the levels of protein structure Globular and fibrous proteins: haemoglobin and collagen Alternative splicing and tissue-specific proteins Enzyme specificity, the active site and activation energy Rates of reaction, Vmax and Core Practical 4 Semi-conservative replication and Meselson-Stahl Types of mutation and the CFTR gene Alleles, genotype and monohybrid inheritance Pedigree diagrams and the inheritance of cystic fibrosis The effects of cystic fibrosis, and the chi-squared test Prenatal genetic testing: PGD, amniocentesis and CVS The ethics of genetic screening

Voice of the Genome

Topic overview Prokaryotic cells Eukaryotic organelles and their functions Identifying organelles in an electron micrograph Protein secretion, and levels of organisation Microscopy: the graticule, magnification and standard form The cell cycle and the stages of mitosis Core practical: the root tip squash Meiosis, linkage and sex linkage The structure of sperm and egg cells Fertilisation: the acrosome and cortical reactions Totipotency, pluripotency and sources of stem cells The ethics and risks of stem cell therapy Differential gene expression and specialisation The lac operon Epigenetics: DNA methylation and histone modification Polygenic inheritance, continuous variation and statistics

Biodiversity and Natural Resources

Topic overview Biodiversity, species richness and the index of diversity Niches and the three kinds of adaptation Natural selection and evolution The Hardy-Weinberg equation and its assumptions Reproductive isolation and speciation Classification The plant cell wall, chloroplast and amyloplast The vacuole, plasmodesmata, pits and middle lamella Plant cells in the electron microscope Starch and cellulose Lignin, xylem vessels and sclerenchyma fibres Identifying plant tissues under the microscope The structure of xylem, phloem and sclerenchyma Water and the mineral nutrition of plants Core practical: investigating mineral deficiency Core practical: the tensile strength of plant fibres Drug development from Withering to modern trials Growing bacteria and aseptic technique Core practical: the antimicrobial properties of plants Sustainability and Conservation

On the Wild Side

Immunity, Infection and Forensics

Topic overview Decomposition, succession and forensic entomology Body cooling and rigor mortis DNA profiling and the polymerase chain reaction Gel electrophoresis The structure of bacteria and viruses Decomposition, and how pathogens enter the body The body's barriers, and modelling bacterial growth Tuberculosis and HIV The non-specific immune response Antigens, antibodies and B cells T cells and cell-mediated immunity Active and passive immunity, natural and artificial The evolutionary race and pathogen evasion Antibiotics and testing their effectiveness Hospital acquired infections and their control

Run for Your Life

Topic overview Muscles and Movement The myofibril and the sarcomere The sliding filament theory, calcium and ATP Slow-twitch and fast-twitch muscle fibres Glycolysis and the link reaction The Krebs cycle, oxidative phosphorylation and oxygen debt The conduction system: SAN, AVN and Purkyne fibres The sequence of cardiac excitation The electrocardiogram, cardiac output and stroke volume The cardiovascular and ventilation control centres Spirometry and ventilation during exercise Homeostasis, feedback and gene control by hormones Thermoregulation and the hypothalamus The effects of too much and too little exercise Medical technology and performance-enhancing substances

Grey Matter

Topic overview The structure of neurones and myelination The action potential and saltatory conduction The structure of a synapse and calcium entry Neurotransmitter release and acetylcholine Rod cells and the detection of light Effectors, the neuromuscular junction and the pupil reflex Phytochrome and the response to light IAA, phototropism and gravitropism Nervous against hormonal coordination The regions of the brain and their functions Brain imaging: MRI, fMRI, PET and CT Critical periods and the Hubel and Wiesel experiments Nature, nurture, habituation and research ethics Dopamine, serotonin and their imbalance L-Dopa and MDMA Genome sequencing, personalised medicine and its ethics Genetically modified organisms: benefits and risks

Lifestyle, Health and Risk

Correlation, causation and the design of health studies

3 things to know
Papers 1, 2 and 3

Overview

Recall questions on using illness and death figures to identify risk, correlation against causation, confounding variables and conflicting evidence, sample selection and size, validity and reliability, accuracy and precision, random and systematic error, and percentage error.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Evaluation

Define correlation in the context of health studies.

Evaluation

Why does sample selection affect the validity of health risk studies?

Key term

What does causation mean in health research?

Questions from this subtopic

Each one with the model answer underneath.

1
How are figures on illness and death used to work out what raises a person's risk?
Model answer
By comparing rates between different populations or groups exposed to different factors, allowing identification of factors associated with increased or decreased risk.
2
Define correlation in the context of health studies.
Model answer
Correlation means two variables show a statistical relationship where they change together, but this does not prove that one causes the other.
3
What does causation mean in health research?
Model answer
Causation means one factor directly produces an effect on another, requiring evidence beyond correlation such as a biological mechanism and controlled experiments.
4
Why is a plausible biological mechanism important when distinguishing correlation from causation?
Model answer
A plausible biological mechanism provides an explanation for how one factor could directly produce the observed effect, supporting a causal rather than coincidental relationship.
5
How does consistency across different studies help distinguish causation from correlation?
Model answer
If the same relationship is found consistently across multiple independent studies with different populations and methods, this strengthens evidence that the relationship is causal rather than due to chance or specific study conditions.
6
Why is controlling confounding variables necessary when establishing causation?
Model answer
Controlling confounding variables ensures that any observed relationship is due to the factor being studied rather than other variables that might influence both the factor and the outcome.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Lifestyle, Health and Risk

Genes and Health

Voice of the Genome

Biodiversity and Natural Resources

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

A base.

nitrogenousphosphatesugar

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

ABMI = mass ÷ height².

BMass is body mass in kilograms.

CHeight is height in metres.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Systole means phase when cardiac muscle contracts.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Lifestyle, Health and Risk, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.