Causes of Non-infectious Disease
- Junessa Masaya
- 5 days ago
- 4 min read
HSC Biology | Study Notes
Causes of non-infectious disease are a key part of NSW Biology Stage 6, Module 8, Non-infectious Disease and Disorders. This topic matters because Module 8 specifically requires students to investigate the causes and effects of non-infectious diseases in humans, including genetic diseases, diseases caused by environmental exposure, nutritional diseases, and cancer. HSC marking guidance also makes clear that non-infectious diseases are not caused by pathogens and do not spread from person to person.
In this lesson
what non-infectious disease means
how genetic causes can lead to disease
how nutritional causes affect health
how environmental exposure can cause disease
how lifestyle factors can increase disease risk
What is a non-infectious disease?
A non-infectious disease is a disease that is not caused by a pathogen and cannot be passed directly from one person to another.
Why this matters
This means non-infectious diseases are caused by other factors, such as:
inherited genes
nutrition
environmental exposure
behaviour and lifestyle
HSC marking guidance states this directly, noting that non-infectious diseases are caused by factors such as environmental factors or inherited genes.
Genetic causes
Some non-infectious diseases are caused by genetic factors.
What this means
A person may inherit:
a faulty allele
a harmful gene combination
a chromosomal abnormality
These can affect how cells, tissues or organs function.
Why genetic causes matter
If a disease has a genetic cause:
it may run in families
risk may be higher in some individuals
prevention may be harder if the cause is inherited
Example idea
The 2019 HSC marking guidelines discuss Alzheimer’s disease risk in relation to different APOE alleles, showing that inherited genes can influence the chance of developing a non-infectious disease.
Nutritional causes
Some non-infectious diseases are caused or strongly influenced by nutrition.
What this means
Nutritional causes involve:
too little of an essential nutrient
too much of a harmful substance
an unbalanced diet over time
Why nutrition matters
The body needs the right balance of nutrients for:
growth
repair
energy supply
normal body function
If this balance is disrupted, disease can develop.
Syllabus link
Module 8 specifically lists nutritional diseases as an area students must investigate.
Environmental causes
Some non-infectious diseases are caused by environmental exposure.
What this means
Environmental causes include exposure to harmful factors in the surroundings, such as:
radiation
pollution
toxic chemicals
harmful particles
excessive UV radiation
Why environmental causes matter
Environmental exposure can damage:
DNA
cells
tissues
organs
This can increase the risk of disease developing over time.
Syllabus link
Module 8 specifically requires students to investigate diseases caused by environmental exposure.
Lifestyle factors
Lifestyle factors are behaviours that can increase or decrease the risk of non-infectious disease.
What this means
Lifestyle factors may include:
smoking
diet
physical activity
alcohol use
sun exposure
Why lifestyle factors matter
Lifestyle factors are important because long-term behaviour can affect:
body systems
organ health
disease risk over many years
HSC-style example
A Module 8 sample resource uses long-term smoking prevalence in Australia and links smoking to lung cancer risk, showing how lifestyle can be connected to non-infectious disease patterns.
Causes often work together
One of the most important ideas in this topic is that non-infectious disease is often multifactorial, meaning more than one cause may be involved.
Example
A person may have:
a genetic predisposition
environmental exposure
lifestyle risks
all contributing to the same disease.
Why this matters
This is why non-infectious disease can be complex to explain and prevent. It is often not caused by one single factor alone.
Cancer as a non-infectious disease
The Module 8 syllabus also specifically includes cancer as part of the causes and effects section.
Why cancer fits this topic
Cancer is non-infectious because it is not usually caused by a transmissible pathogen. Instead, it is linked to:
genetic changes
environmental exposures
sometimes lifestyle factors
Important point
Cancer is a good example of how genetic, environmental and lifestyle causes can interact.
Comparing the main causes
Cause type | Main idea | Example idea |
Genetic | Inherited or spontaneous genetic change affects function | Disease linked to inherited alleles |
Nutritional | Poor or unbalanced nutrient intake affects health | Nutritional deficiency or excess |
Environmental | Exposure to harmful external agents damages the body | UV radiation or pollutants |
Lifestyle | Behaviour over time changes disease risk | Smoking, poor diet, low activity |
Why this topic matters in Module 8
This topic is important because it builds the foundation for the rest of Module 8:
analysing incidence and prevalence
interpreting epidemiological data
evaluating prevention methods
understanding treatment and management
Students need to understand the causes first before they can explain patterns of non-infectious disease in populations.
Worked example
Exam-style question
Explain how one lifestyle factor can contribute to a non-infectious disease.
Worked answer
Smoking is a lifestyle factor that can increase the risk of lung cancer. Repeated exposure to harmful chemicals in cigarette smoke can damage body tissues and increase the chance of disease developing over time. A Module 8 resource links smoking prevalence with lung cancer patterns in Australia.
Why this works
This answer:
identifies one lifestyle factor
links it to a named non-infectious disease
explains the connection clearly
Common mistakes
Saying non-infectious diseases are caused by pathogens.
Treating genetic, environmental and lifestyle causes as completely separate when they often interact.
Forgetting that nutritional disease is specifically part of the Module 8 syllabus.
Giving an example of infection instead of non-infectious disease.
Describing a cause without explaining how it affects health.
Quick quiz
What is a non-infectious disease?
How can genes contribute to non-infectious disease?
What is meant by a nutritional cause of disease?
Give one example of an environmental cause of disease.
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