Health issues — AQA GCSE Combined Science

Health is defined by the World Health Organization as a state of complete physical, mental, and social well-being, rather than merely the absence of disease. In AQA GCSE Combined Science, studying health issues involves understanding how communicable and non-communicable diseases interact, alongside the biological impacts of lifestyle risk factors.

Health and disease is a foundational biology topic within AQA GCSE Combined Science that explores physical, mental, and social well-being. It focuses on distinguishing between communicable diseases caused by pathogens and non-communicable diseases caused by genetic, environmental, and lifestyle factors.

Understanding health issues provides essential context for public health, epidemiological data analysis, and human physiology. It directly connects cellular biology and organ systems to real-world medical challenges such as cardiovascular disease, cancer, and diabetes.

• →Health is a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity.
• →Diseases can interact: immune deficiencies increase susceptibility to infectious diseases, viruses can trigger cancers, and severe physical ill health often triggers depression.
• →Risk factors (lifestyle choices like smoking, poor diet, and alcohol, or environmental substances like radiation) are linked to an increased rate of disease.
• →A causal mechanism explains how a specific risk factor biologically produces a disease, going beyond simple statistical correlation.
• →Benign tumours stay in one place and do not invade other tissues, whereas malignant tumours are cancerous, invading neighbouring tissues and spreading via blood to form secondary tumours.

• Define health as a state of physical and mental well-being, not just the absence of disease.
• Identify factors that affect health, such as diet, stress, life situations and healthcare.
• Describe how a communicable disease can worsen a non-communicable disease, for example a chest infection worsening asthma.
• Explain how a non-communicable disease or its treatment can weaken the immune system and increase the risk of communicable disease.
• Give an example of a virus triggering cancer, such as HPV and cervical cancer.
• Describe how mental health problems can affect physical health and vice versa.
• Health is defined as a state of physical and mental well-being, not merely the absence of disease.
• Physical well-being includes freedom from disease and injury plus the body functioning adequately for everyday activity.
• Mental well-being includes emotional and social functioning, such as coping with stress and maintaining supportive relationships.
• The two aspects interact: a physical illness can worsen mental health and poor mental health can affect physical health.
• Health is judged from evidence about a person's body and mind compared with normal function for that individual.
• Communicable diseases are caused by pathogens and can be spread between organisms, for example influenza and malaria.
• Non-communicable diseases are not transmitted between people and include cancer, type 2 diabetes and coronary heart disease.
• Both communicable and non-communicable diseases are major causes of ill health.
• Diet can cause ill health, for example deficiency diseases from missing nutrients or obesity and type 2 diabetes from excess energy intake.
• Stress and life situations such as poor housing, low income or pollution can profoundly affect physical and mental health.
• Risk factors often interact, so one factor can increase the effect of another on health.
• Communicable diseases are caused by pathogens and can be spread between organisms, whereas non-communicable diseases are not transmitted and include conditions such as type 2 diabetes and coronary heart disease.
• A communicable disease can increase the risk of a non-communicable disease, for example a viral infection may trigger certain cancers or long-term organ damage.
• A non-communicable disease can increase the risk of a communicable disease, for example diabetes can lead to poor wound healing and increased susceptibility to infection.
• A communicable disease can make another communicable disease more severe, for example HIV destroys lymphocytes so the body cannot fight off infections such as tuberculosis.
• Interactions can be described using specific named examples, and the direction of the effect should be stated clearly rather than simply listing two diseases.
• The immune system involves white blood cells such as lymphocytes and phagocytes that recognise and destroy pathogens.
• A defect in the immune system reduces the body's ability to recognise or destroy pathogens, so infectious diseases are more likely.
• Named examples include HIV, which destroys lymphocytes, and inherited conditions such as severe combined immunodeficiency.
• Medical treatments such as chemotherapy and immunosuppressant drugs can weaken the immune system and increase the risk of infection.
• The consequence of a defective immune system is that infections may be more frequent, more severe, or caused by opportunistic pathogens.
• Viruses are obligate intracellular parasites and must live inside host cells to replicate.
• Viral genetic material can be inserted into the host cell DNA, altering normal gene function.
• Changes to genes controlling the cell cycle, such as tumour suppressor genes and proto-oncogenes, can lead to uncontrolled cell division.
• Uncontrolled cell division produces a tumour; a malignant tumour that invades and spreads is a cancer.
• A named example is human papillomavirus (HPV) infecting cervical cells and being linked to cervical cancer.
• Not all viral infections cause cancer; additional mutations or risk factors are usually involved.
• State that an immune reaction initially caused by a pathogen can trigger allergies.
• Identify skin rashes and asthma as examples of allergies triggered by such immune reactions.
• Explain that this is an example of how different types of diseases (communicable and non-communicable) can interact.
• Describe asthma as a condition affecting the airways, which can be triggered by an overactive immune response following an infection.
• States that health includes both physical and mental wellbeing, not merely the absence of disease.
• Explains that severe or long-term physical illness can act as a trigger or risk factor for depression and other mental illnesses.
• Gives a plausible mechanism, such as chronic pain, disability, loss of independence, social isolation or worry about the future.
• Uses a specific example, such as severe arthritis, cancer or a long-term heart condition, linked to depression.
• Recognises that the relationship can be two-way, because mental illness can also worsen physical health.
• Concludes that effective care may need to address physical and mental health together.
• Defines disease incidence as the number of new cases in a population over a given time period.
• Constructs a frequency table with correctly labelled categories or intervals and matching frequencies.
• Chooses a bar chart for discrete categories and a histogram for continuous grouped data, with bars touching in a histogram.
• Reads values accurately from a graph or table and converts between graphical and numerical forms.
• Plots a scatter diagram with the explanatory variable on the x-axis and the response variable on the y-axis.
• Identifies positive, negative or no correlation from the overall pattern of points on a scatter diagram.
• Interprets a correlation as an association, not proof that one variable causes the other.
• Define the population as the whole group being studied and the sample as the subset selected for measurement.
• Explain that a representative sample must reflect the variation within the population, including relevant subgroups.
• Describe random sampling as giving every member of the population an equal chance of selection, reducing bias.
• State that increasing sample size reduces the influence of chance and improves the reliability of conclusions.
• Apply sampling ideas to epidemiological data, such as comparing disease frequency between exposed and unexposed groups.
• Recognise that correlation between a factor and a disease does not establish causation because confounding variables may exist.

• 💡Use a named example for each interaction, such as a chest infection worsening asthma.
• 💡Write cause and effect sentences: 'because the immune system is weakened, the person is more likely to...'.
• 💡If asked to describe, give the link between the diseases rather than listing many diseases.
• 💡Quote the full definition and then unpack both 'physical' and 'mental' in your own words.
• 💡Use a named example, such as a person with asthma whose anxiety worsens breathlessness, to show the interaction.
• 💡If asked to evaluate a case study, comment on both physical and mental evidence before concluding.
• 💡Classify each disease in a question as communicable or non-communicable before explaining its effect.
• 💡Link every risk factor to a specific physical or mental health outcome rather than leaving it as a list.
• 💡Use connectives such as 'which increases the risk of' to show cause and effect clearly.
• 💡Use the command word in the question: if asked to explain, give a mechanism linking the two diseases rather than just naming them.
• 💡Choose one clear example, such as HIV and tuberculosis, and state the effect of HIV on lymphocytes and the consequence for other infections.
• 💡Link your answer to the idea of health as a state of physical and mental well-being, so that interactions are placed in the wider context of disease risk.
• 💡Name the relevant white blood cells and state their role when explaining why a defect increases infection risk.
• 💡Use a specific example such as HIV destroying lymphocytes, and link this to a named infection such as tuberculosis.
• 💡If the question asks about a treatment, explain how the treatment reduces immune function rather than simply naming the treatment.
• 💡Use the phrase 'uncontrolled cell division' when explaining how a tumour forms, and link it to a change in the host cell's genes.
• 💡Give one named example, such as HPV and cervical cancer, to show the link is real rather than theoretical.
• 💡If asked to evaluate, mention that the link is a risk factor, not a certainty, and refer to prevention such as vaccination.
• 💡When asked about disease interactions, use the specific example that an immune reaction to a pathogen can trigger allergies like asthma or skin rashes.
• 💡Clearly distinguish between the initial infection (caused by a pathogen) and the subsequent allergy (caused by the immune system).
• 💡Use the phrase 'can lead to' rather than 'always causes' to show that the link is a risk, not a certainty.
• 💡Include one named physical condition and one named mental illness, then explain the link between them in a single sentence.
• 💡If asked to suggest why a patient is depressed, refer to specific consequences of the physical illness such as pain, reduced mobility or loss of independence.
• 💡Label both axes with the quantity and its unit, and give the graph a title that names the disease and time period.
• 💡When reading a histogram, check the scale on the frequency density axis before estimating a frequency.
• 💡Describe a correlation using both its direction and strength, for example 'a strong negative correlation', and avoid saying 'the points are random' without checking the overall pattern.
• 💡Name the population, the sample and the sampling method explicitly when describing a study.
• 💡Use the phrase 'representative of the population' and justify it with a feature of the sampling method.
• 💡When interpreting epidemiological data, comment on sample size, possible bias and confounding variables before concluding.
• 💡Use precise terms when describing tumours: state that malignant cells 'invade neighbouring tissues' and 'spread via the bloodstream to form secondary tumours'.
• 💡When evaluating health data from scatter graphs, always look for sample size, duration of study, and whether other confounding variables were controlled.
• 💡Clearly separate the effects of nicotine (addiction, increased heart rate) from carbon monoxide (binds irreversibly to haemoglobin) and tar (carcinogenic).

• Defining health as simply 'not being ill'; correct this by including physical and mental well-being.
• Treating communicable and non-communicable diseases as completely separate; correct this by giving an example where one affects the other.
• Assuming a weakened immune system only causes allergies; correct this by linking it to increased risk of communicable disease.
• Saying health is just 'not being ill'. Correction: the definition requires both physical and mental well-being, so a disease-free person with severe anxiety is not fully healthy.
• Treating mental well-being as separate from physical health. Correction: the two influence each other, for example long-term pain can cause low mood and low mood can reduce self-care.
• Assuming a single measurement, such as body mass index, proves health. Correction: health is a state assessed from several pieces of evidence about body and mind.
• Calling all diseases communicable. Correction: non-communicable diseases such as cancer are not spread between people.
• Assuming a risk factor directly causes a disease. Correction: a risk factor increases the chance of ill health but does not guarantee it.
• Listing factors without linking them to physical or mental effects. Correction: state the effect, for example stress raising blood pressure or poor diet causing deficiency disease.
• Thinking that all diseases are infectious: correction — non-communicable diseases such as asthma and type 2 diabetes are not caused by pathogens and cannot be passed from person to person.
• Assuming that if two diseases occur together they must directly cause each other: correction — an interaction must be explained, for example by stating how one condition weakens defences or damages an organ, rather than just naming two conditions.
• Confusing correlation with causation: correction — a statistical link between two diseases does not prove that one causes the other; a biological mechanism should be described.
• Confusing a defect in the immune system with a defect in the nervous system: correction — the immune system involves white blood cells and defences against pathogens, not nerve impulses.
• Thinking that a weakened immune system directly causes infectious disease: correction — infectious diseases are caused by pathogens; a weakened immune system increases the likelihood that pathogens will cause disease.
• Believing that all white blood cells produce antibodies: correction — lymphocytes produce antibodies, whereas phagocytes engulf and digest pathogens.
• Thinking viruses are cells: correct this by stating viruses are much smaller than cells, are not cells, and must reproduce inside a host cell.
• Believing a virus directly 'eats' or destroys tissue to form a cancer: correct this by explaining that cancer arises from altered control of the host cell cycle, not from direct digestion.
• Assuming every infection with a cancer-linked virus causes cancer: correct this by noting that cancer usually requires further genetic changes and other risk factors.
• Believing that allergies are directly caused by the pathogen itself; correction: the allergy is caused by the immune system's overreaction, which was initially triggered by the pathogen.
• Confusing communicable and non-communicable diseases; correction: while the initial pathogen causes a communicable disease, the resulting allergy (like asthma) is non-communicable.
• Thinking asthma is an infection; correction: asthma is an allergic reaction that affects the airways, even though it may be triggered by a prior immune response to an infection.
• Writing that physical illness directly causes mental illness in every patient; correction: it increases the risk or can lead to mental illness, but not all patients become depressed.
• Treating mental illness as less real or less important than physical illness; correction: both are genuine health conditions that affect wellbeing and can interact.
• Describing only the effect of mental illness on physical health and ignoring the stated direction; correction: answer the statement by explaining how severe physical ill health can lead to depression and other mental illness.
• Leaving gaps between bars in a histogram; correction: histogram bars touch because the data are continuous and grouped into intervals.
• Using a bar chart for continuous data such as age ranges; correction: use a histogram when data are grouped into numerical intervals.
• Claiming that a correlation proves causation; correction: a correlation shows an association, and other factors may explain it.
• Confusing the sample with the population: the sample is the measured subset, while the population is the whole group about which conclusions are drawn.
• Assuming a bigger sample automatically removes bias: a large biased sample, such as volunteers from one gym, is still unrepresentative.
• Treating a correlation as proof of cause: an observed link may result from confounding variables, so further evidence is needed.
• Believing all tumours are cancerous; benign tumours are non-invasive and contained within a membrane, whereas only malignant tumours are classified as cancer.
• Assuming correlation automatically proves that one factor causes another; proving causation requires experimental proof of an exact biological mechanism.
• Thinking non-communicable diseases are contagious or caused directly by pathogens like bacteria and viruses.

1. 1Day 1-2: Master core definitions (health, communicable vs non-communicable, correlation vs causation) and disease interactions.
2. 2Day 3-4: Focus on lifestyle risk factors and their biological causal mechanisms (smoking, alcohol, diet, UV light).
3. 3Day 5: Study cancer biology, clearly contrasting benign and malignant tumours using AQA exam phrasing.
4. 4Day 6-7: Practice interpreting epidemiological graphs and answer 4-mark and 6-mark extended response questions under timed conditions.

• 📋Graph interpretation questions: Identifying trends between risk factors and disease rates, noting positive or negative correlations.
• 📋Explain questions: Stating a causal mechanism (e.g. explain how smoking increases the risk of cardiovascular disease).
• 📋Comparison questions: Comparing benign and malignant tumours in a structured table or short answer format.
• 📋6-mark extended evaluation questions: Evaluating the economic, personal, and societal impact of non-communicable diseases.