Health Issues (AQA GCSE Biology): Revision Note

Health & disease

• Health is the state of physical and mental well-being; it is affected by multiple factors

Communicable and non-communicable diseases

• Diseases, both communicable and non-communicable, are major causes of ill health

• Ill-health affects not only the sufferer but also their family members and the contribution that the individual can make to society

  • Ill health can lead to a poorer quality of life or a reduced lifespan

  • Illness may generate financial costs

    • Individuals who are ill may not be able to work and may require expensive healthcare

Communicable diseases

• Communicable diseases are caused by microorganisms called pathogens which can spread between individuals or individuals and animals

• Examples of communicable diseases are:

  • chickenpox, a common childhood disease, is caused by a viral pathogen called the varicella-zoster virus

  • covid-19 is caused by the SARS-CoV-2 virus

Non-communicable diseases

• Non-communicable diseases are not caused by pathogens and their effects on health tend to be longer-lasting

• Examples of non-communicable diseases include:

  • asthma

  • coronary heart disease (CHD)

  • cancers

Factors affecting health

• Lifestyle factors may have a profound effect on both physical and mental health, e.g.:

  • eating a balanced diet that provides the right amount of energy and nutrients helps maintain good health

  • a poor diet can lead to deficiencies, obesity, diabetes and poor mental health

  • constantly being under stress can lead to cardiovascular issues (such as high blood pressure, increasing the risk of CHD) and poor mental health

  • where a person lives and their income can have a profound impact on their health, affecting the standard of healthcare that is accessible to them and what housing and food they can afford

Interactions & disease

• The effects of different types of disease may interact in ways that negatively affect the health of the individual, e.g.:

  • An individual with non-communicable immune deficiency may be more likely to suffer from communicable diseases

  • HIV, a viral infection, affects the immune system and may make someone more susceptible to bacterial infection

  • Viruses living in cells can be the trigger for cancers

    • E.g. HPV infection can increase the risk of cervical cancer

  • 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

Disease incidence: Representing & calculating

• Scientists and doctors often record the incidence of disease – the number of new cases seen in a population over a set time period (e.g. number of measles cases per month)

• Data on disease can take place in a variety of forms:

  • Graphical and numerical forms

    • Data can be presented as a table, which can be extracted into an appropriate graph; from there, numerical data can be extracted from the chart

    • Graphs must have clearly labelled axes and appropriate scales

  • Frequency tables, bar charts and histograms

    • Frequency tables present how many cases occur in each category

    • Bar charts are used for discrete data (e.g. cases per month)

    • Histograms are used for continuous data (e.g. ages of infected patients)

  • Correlations on scatter diagrams

    • Scatter diagrams plot two variables (e.g. pollution level vs. number of asthma cases)

    • Positive correlation: both variables increase together

    • Negative correlation: one variable increases as the other decreases

    • No correlation: no clear pattern

    • Correlation does not prove causation – the link between variables may be due to another factor

Sampling

• Epidemiology is the study of the spread of disease

• When investigating the spread of disease, it is often impractical to collect data from every individual in a population; scientists therefore take a sample

  • This involves collecting data from a smaller number of individuals and using the results to represent a larger population

Importance of sampling

• Sampling saves time and resources while still allowing meaningful data collection

• Large, well-chosen samples produce more reliable and representative results

• Take several samples, find the mean, then scale up to the whole population or volume (e.g. if each sample is 0.02 cm³, multiply the mean count by 50 to estimate the number per 1 cm³). Scaling up from a single sample is not reliable

Sampling in epidemiology

• Sampling enables scientists to identify patterns of disease spread, risk factors, and vulnerable groups

• Findings are used to guide public health strategies, such as vaccination campaigns or screening programmes