Health issues — AQA GCSE Biology
Test yourself on Health issues with AQA GCSE practice questions.
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Health issues explained
Health is a state of physical and mental well-being.
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Disease can disrupt this state, and different diseases often interact. A communicable disease may weaken the body, making a non-communicable disease more likely or more severe. For example, defects in the immune system mean an individual is more likely to suffer from infectious diseases. Viruses living in cells can be the trigger for cancers. Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma. Furthermore, severe physical ill health can lead to depression and other mental illness. Understanding these interactions helps explain why treating one disease can improve overall health and why prevention is important.
Health is the state of physical and mental well-being.
Health is a complete state of physical and mental well-being, not simply the absence of disease or infirmity. Physical well-being includes having a healthy body that functions properly, free from illness and injury. Mental well-being includes feeling positive about oneself, being able to cope with normal stresses, and having good emotional and social functioning. For example, a person with a broken leg has physical ill health, while someone experiencing depression has mental ill health. Both aspects are equally important and can influence each other. A person may have no diagnosed disease but still feel unwell mentally, or may have a physical condition but maintain good mental well-being. This holistic definition is used by the World Health Organization and is central to understanding health issues.
Diseases, both communicable and non-communicable, are major causes of ill health.
Ill health can be caused by many factors, but diseases are major contributors. Communicable diseases are caused by pathogens such as bacteria, viruses, fungi and protists, and can be transmitted from person to person or from other organisms. Examples include influenza, malaria and tuberculosis. Non-communicable diseases are not caused by pathogens and cannot be transmitted between people. They include conditions such as cancer, diabetes, heart disease and asthma. Both types of disease can cause physical and mental ill health, reduce quality of life, and may lead to death. They also place a burden on healthcare systems. Understanding the difference between communicable and non-communicable diseases is essential for studying health issues and planning prevention strategies.
Other factors including diet, stress and life situations may have a profound effect on both physical and mental health.
Health is influenced by many factors beyond diseases. Diet, stress and life situations can have profound effects on both physical and mental well-being. A balanced diet provides essential nutrients and energy, supporting physical health; a poor diet can lead to malnutrition, obesity, type 2 diabetes and heart disease, and can also affect mental health. Stress, especially when prolonged, can cause physical symptoms such as high blood pressure and increase the risk of mental health issues like anxiety and depression. Life situations include housing, income, education, employment and social support. Poor housing or financial hardship can increase stress and limit access to healthy food and healthcare, worsening both physical and mental health. These factors often interact; for example, stress may lead to unhealthy eating, which further affects health.
Different types of disease may interact.
Diseases rarely occur in isolation. A communicable disease can weaken the body so a non-communicable disease develops, or a non-communicable disease can make a communicable infection more likely or more severe. For example, infection with HIV destroys lymphocytes, so the immune system cannot control other pathogens and the person may develop AIDS-related infections. Conversely, a poor diet causing anaemia reduces oxygen transport, so tissues heal slowly and infection risk rises. Another interaction is that a pathogen can trigger an immune reaction that damages healthy tissue, as in rheumatic fever affecting the heart. Students should describe a specific interaction, name the diseases involved and explain the causal chain linking them, rather than simply listing two conditions.
Defects in the immune system mean that an individual is more likely to suffer from infectious diseases.
The immune system defends the body against pathogens such as bacteria, viruses, fungi and protists. White blood cells engulf pathogens and produce antibodies or antitoxins. If any part of this defence is defective, pathogens are not destroyed efficiently, so they multiply and cause infectious disease more often and often more severely. Defects may be inherited, such as severe combined immunodeficiency, or acquired, for example through infection with HIV, which destroys helper T cells, or through drugs that suppress immunity after a transplant. A student can reason from cause to effect: fewer functional white blood cells means weaker phagocytosis and antibody production, so a common pathogen such as Mycobacterium tuberculosis is more likely to establish infection. This links immune function to health, disease transmission and vaccination.
Viruses living in cells can be the trigger for cancers. • Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
Two indirect health effects are described. First, some viruses insert genetic material into host cells and disrupt normal control of cell division, so cells divide uncontrollably and a tumour forms; examples include human papillomavirus linked to cervical cancer and hepatitis B linked to liver cancer. Second, an immune reaction that begins as a defence against a pathogen can become misdirected or exaggerated, producing allergy symptoms. For example, an infection may prime immune cells so that later exposure to a harmless allergen triggers histamine release, causing a skin rash, or narrowing of the airways in asthma. Students should distinguish the pathogen as the initial trigger from the allergen or cancer that follows, and explain the sequence rather than simply naming a disease.
Severe physical ill health can lead to depression and other mental illness.
Health is not merely the absence of disease; it is a state of physical and mental well-being. Severe physical ill health, such as cancer, chronic heart disease or long-term disability, can disrupt daily life, cause persistent pain, limit independence and create uncertainty about the future. These stresses can trigger depression, anxiety and other mental illnesses. The relationship can also work in reverse: mental illness may reduce self-care, exercise and healthy eating, worsening physical health. A useful model is a two-way feedback loop: a long-term physical condition increases stress and reduces activity, which lowers mood, which further reduces activity and recovery. Understanding this interdependence explains why treatment often addresses both physical and mental health together.
Students should be able to translate disease incidence information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.
This skill statement requires students to move between numerical data and graphical displays of disease incidence. Incidence means the number of new cases in a population over a period. Students should read values from a graph and write them as numbers, and plot numerical data accurately. A frequency table records how often each category or value occurs; a bar chart shows frequencies for discrete categories with gaps between bars; a histogram shows frequencies for continuous data with bars touching. A scatter diagram plots paired values for two variables, and students identify correlation by the overall pattern: positive, negative or no correlation. For example, plotting incidence of a disease against year can show a trend, while plotting incidence against a risk factor can suggest a correlation, though correlation does not prove causation.
Students should understand the principles of sampling as applied to scientific data, including epidemiological data.
Sampling means studying a subset of a population to draw conclusions about the whole population. Because it is usually impossible to measure every person, researchers select a sample. A representative sample reflects the population's key features, such as age, sex and location, so results can be generalised. Random sampling gives every member an equal chance of selection and reduces bias. Sample size matters: larger samples usually give more reliable estimates, though they take more time and resources. In epidemiology, scientists sample populations to estimate disease incidence, identify risk factors and monitor outbreaks. For example, testing a random sample of 1,000 people for a disease can estimate its prevalence in a city, but the estimate is uncertain and may not represent groups left out of the sample.
Your focus
- Define health as a state of physical and mental well-being.
- Describe how defects in the immune system increase susceptibility to infectious diseases.
- Explain how physical ill health can lead to mental illness and how immune reactions can trigger allergies.
Show all 30 objectives
- State the definition of health.
- Describe what is meant by physical and mental well-being.
- Explain why health is not just the absence of disease.
- Define communicable and non-communicable diseases.
- Give examples of communicable and non-communicable diseases.
- Explain why both types of disease are major causes of ill health.
- Describe how diet can affect physical and mental health.
- Explain how stress can affect physical and mental health.
- Discuss how life situations can influence health.
- Describe at least one way in which two different diseases can interact.
- Explain the causal mechanism linking a named disease to a second disease.
- Apply the idea of disease interaction to an unfamiliar example.
- Describe how white blood cells defend the body against pathogens.
- Explain how a defect in the immune system increases the likelihood of infectious disease.
- Apply knowledge of immune defects to unfamiliar contexts such as HIV infection or immunosuppressive treatment.
- Describe how viruses can trigger cancer by disrupting normal cell division.
- Explain how an immune reaction initially caused by a pathogen can lead to allergies such as skin rashes and asthma.
- Distinguish between the initial trigger and the resulting health condition in each example.
- State that health includes both physical and mental well-being.
- Describe how severe physical ill health can increase the risk of depression and other mental illnesses.
- Explain at least one way in which mental illness can affect physical health.
- Convert disease incidence data between numerical and graphical forms.
- Construct frequency tables, bar charts and histograms correctly.
- Use a scatter diagram to identify and describe a correlation between two variables.
- Describe the principles of sampling a population.
- Explain why a representative sample is needed for valid conclusions.
- Apply sampling ideas to interpret epidemiological data and identify possible bias.
Health issues exam tips
Marking Points
- Health is a state of physical and mental well-being, not just the absence of disease.
- Defects in the immune system mean an individual is more likely to suffer from infectious diseases.
- Viruses living in cells can be the trigger for cancers.
- Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
- Severe physical ill health can lead to depression and other mental illness.
- Health is defined as a state of physical and mental well-being.
- Physical well-being relates to the body's functioning and absence of disease or injury.
- Mental well-being relates to emotional and psychological state, including ability to cope with stress.
- Health is not just the absence of disease; a person can have a disease but still have good mental well-being, or vice versa.
- Both physical and mental aspects are equally important and can affect each other.
- Communicable diseases are caused by pathogens and can be transmitted between individuals.
- Non-communicable diseases are not caused by pathogens and are not transmissible.
- Both communicable and non-communicable diseases are major causes of ill health.
- Examples of communicable diseases include influenza, malaria and tuberculosis.
- Examples of non-communicable diseases include cancer, diabetes and heart disease.
- Diseases can cause physical and mental ill health and can be fatal.
- Diet affects physical health; a balanced diet is needed for good health, while poor diet can cause malnutrition or obesity.
- Diet can also affect mental health; for example, deficiencies in certain nutrients may affect mood and brain function.
- Stress can have physical effects, such as increased blood pressure and risk of heart disease.
- Stress can have mental effects, such as anxiety and depression.
- Life situations include housing, income, education, employment and social support.
- Poor life situations can increase stress and limit access to healthy food and healthcare, affecting both physical and mental health.
- These factors often interact; for example, stress may lead to poor diet, which worsens health.
- States that one disease can increase the risk of another disease developing.
- Explains a causal mechanism, such as a weakened immune system allowing a secondary infection.
- Uses a named example, such as HIV destroying lymphocytes so opportunistic infections occur.
- Distinguishes between communicable and non-communicable diseases and explains how one can influence the other.
- Describes how a pathogen can trigger an immune response that damages body tissues, leading to further disease.
- The immune system uses white blood cells to engulf pathogens and to produce antibodies and antitoxins that destroy pathogens or neutralise their toxins.
- A defect means one or more of these defences work less effectively, for example too few functional white blood cells or reduced antibody production.
- Because pathogens are not destroyed efficiently, they reproduce inside the body and the individual develops an infectious disease more readily.
- Defects can be inherited, caused by a pathogen such as HIV, or caused by medical treatment that suppresses the immune system.
- The consequence is increased frequency and often increased severity of infections, not a direct cause of non-infectious diseases such as scurvy.
- A valid explanation links the defective defence mechanism to pathogen survival and multiplication, then to the symptoms of infectious disease.
- Some viruses enter host cells and alter the control of the cell cycle, causing uncontrolled cell division and tumour formation.
- A named example strengthens the answer, such as human papillomavirus and cervical cancer or hepatitis B and liver cancer.
- An immune reaction first caused by a pathogen can later be triggered by a harmless substance, producing an allergic response.
- Allergy symptoms arise from immune chemicals such as histamine, which cause effects such as skin rashes, swelling or airway narrowing in asthma.
- The pathogen is the initial trigger; the cancer or allergy is a consequence, so the causal sequence must be stated clearly.
- The two clauses are separate mechanisms and should be explained independently rather than merged into one process.
- Health is a state of physical and mental well-being, not just the absence of disease.
- Severe or long-term physical illness can cause pain, disability, loss of independence and financial or social stress.
- These stresses can lead to depression, anxiety and other mental illnesses.
- The link is often two-way: mental illness can also worsen physical health by reducing self-care, exercise or healthy eating.
- Recognising the link supports holistic care, such as treating pain, offering psychological support and encouraging social contact.
- Translate data between numerical tables and graphical displays accurately.
- Construct a frequency table by tallying how often each category or value occurs.
- Draw and interpret bar charts for discrete categories, leaving gaps between bars.
- Draw and interpret histograms for continuous data, with bars touching.
- Plot paired data on a scatter diagram and describe the correlation as positive, negative or none.
- Distinguish correlation from causation when interpreting a scatter diagram.
- Define sampling as studying a subset of a population to make inferences about the whole.
- Explain that a representative sample reflects the characteristics of the population.
- Describe random sampling as giving every member of the population an equal chance of selection.
- Explain that larger samples generally give more reliable estimates than smaller samples.
- Apply sampling principles to epidemiological data, such as estimating disease incidence or prevalence.
- Recognise that biased or unrepresentative samples can lead to invalid conclusions.
Examiner Tips
- 💡Use the definition of health to start your answer, then give a specific example of an interaction between two diseases.
- 💡When describing interactions, state clearly how one affects the other, such as physical ill health leading to mental illness.
- 💡Learn the exact definition: 'Health is the state of physical and mental well-being.'
- 💡Give examples to show you understand both physical and mental aspects.
- 💡Avoid saying health is just about being free from disease; always mention mental well-being.
- 💡Learn the definitions of communicable and non-communicable diseases and be able to give examples of each.
- 💡When asked about causes of ill health, mention both types of disease and give specific examples.
- 💡Use the terms 'communicable' and 'non-communicable' correctly in your answers.
- 💡When discussing factors affecting health, always consider both physical and mental aspects.
- 💡Use specific examples to illustrate how diet, stress or life situations can affect health.
- 💡Link factors together to show interactions, such as how stress might lead to poor diet.
- 💡Use the command word to decide whether you need a simple link or a full causal chain.
- 💡Name specific diseases and the cells or organs affected to make the interaction concrete.
- 💡Link back to the question by stating clearly how the first disease makes the second more likely.
- 💡Use the chain 'defect → reduced phagocytosis or antibody production → pathogens survive and multiply → infectious disease' to structure an explanation.
- 💡Name a specific defect or cause, such as HIV destroying helper T cells, to show understanding beyond a general statement.
- 💡When asked to explain rather than state, include the mechanism of white blood cell action before linking it to increased infection risk.
- 💡Check that every clause of the question is addressed, including both the defect and the increased likelihood of infectious disease.
- 💡Use the wording 'trigger' to show that the virus or pathogen starts a process rather than being the disease itself.
- 💡Give one named virus–cancer link and one named allergic condition to demonstrate breadth.
- 💡For allergy questions, sequence the answer: pathogen exposure → immune sensitisation → allergen exposure → histamine release → symptoms.
- 💡Keep the two bullet points separate in your answer so each mechanism is clearly credited.
- 💡Use the definition of health to frame your answer, then explain the link with a named example such as chronic pain or cancer.
- 💡Include the reverse direction, showing that mental illness can also affect physical health, to reach the highest level.
- 💡Link your explanation to real consequences such as difficulty working, reduced social contact or poorer recovery.
- 💡Label both axes with the variable and unit, and give the graph a clear title.
- 💡Use a sharp pencil and plot points accurately; a point plotted one square out can change the apparent correlation.
- 💡When describing a scatter diagram, state the type and strength of correlation and refer to the overall pattern, not a single point.
- 💡Use the phrase 'representative of the population' when explaining why a sample is useful.
- 💡Link sample size to reliability: larger samples generally give more reliable estimates.
- 💡When evaluating epidemiological data, comment on who was sampled, how they were selected and whether the sample was large enough.
Common Mistakes
- Thinking that health is only about physical fitness; correction: health includes both physical and mental well-being.
- Reversing the causal link between physical and mental health; correction: severe physical ill health can lead to mental illness, not just the other way around.
- Assuming allergies cause immune reactions; correction: immune reactions initially caused by a pathogen can trigger allergies.
- Defining health as only physical fitness; correction: health includes mental well-being as well.
- Thinking that if you are not ill, you are healthy; correction: health also requires mental well-being, so you could be physically well but mentally unwell.
- Confusing mental well-being with mental illness; correction: mental well-being is a positive state, while mental illness is a diagnosed condition.
- Thinking that all diseases are communicable; correction: many diseases, such as cancer and diabetes, are non-communicable.
- Believing that non-communicable diseases cannot be serious; correction: non-communicable diseases are major causes of ill health and death worldwide.
- Confusing the cause of communicable diseases with that of non-communicable diseases; correction: communicable diseases are caused by pathogens, while non-communicable diseases have other causes such as genetics, lifestyle or environment.
- Thinking that only diseases affect health; correction: diet, stress and life situations also have profound effects.
- Believing that stress only affects mental health; correction: stress can also cause physical problems such as high blood pressure.
- Assuming that diet only affects physical health; correction: diet can also influence mental well-being.
- Treating diseases as independent events and listing two conditions without linking them; correct by explaining the causal pathway from the first disease to the second.
- Confusing correlation with causation, for example saying that people with a disease always catch another; correct by using words such as increases the risk or makes more likely.
- Describing HIV as directly killing the person rather than destroying lymphocytes so the immune system fails; correct by explaining the role of lymphocytes in defence.
- Saying a defective immune system directly causes infectious diseases; correct this by stating that pathogens cause the disease and the defect only increases susceptibility.
- Confusing a weak immune system with an autoimmune reaction; correct this by distinguishing reduced defence against pathogens from the immune system attacking the body's own cells.
- Claiming that all infections in an immunocompromised person are caused by a new mutation; correct this by explaining that ordinary environmental pathogens are simply not controlled.
- Describing antibodies as cells; correct this by stating that antibodies are proteins produced by white blood cells.
- Stating that a virus is a cancer cell; correct this by saying the virus triggers changes in host cells that lead to uncontrolled division.
- Saying allergies are caused directly by the pathogen rather than by an immune reaction that the pathogen initially triggered.
- Confusing the roles of histamine and antibodies; correct this by describing histamine as a chemical released during an allergic response.
- Treating all viruses as carcinogenic; correct this by specifying that only some viruses are linked to particular cancers.
- Treating physical and mental health as completely separate; correct by explaining that they interact and influence each other.
- Assuming that physical illness always causes mental illness; correct by stating that it increases the risk rather than making it inevitable.
- Describing mental illness as less serious than physical illness; correct by recognising that both affect health and daily functioning.
- Leaving gaps between bars in a histogram; correct this by making bars touch because the data are continuous.
- Putting gaps between bars in a bar chart incorrectly removed; correct this by keeping gaps because the categories are discrete.
- Claiming that a correlation proves one variable causes the other; correct this by stating that correlation shows a relationship but does not prove causation.
- Assuming a sample always represents the population; correct this by checking whether the sample is representative and large enough.
- Confusing random sampling with haphazard or convenience sampling; correct this by explaining that random sampling gives every member an equal chance of selection.
- Thinking a larger sample guarantees a perfect result; correct this by stating that larger samples usually improve reliability but do not remove all error or bias.