- Non-infectious diseases are not caused by transmissible pathogens.
- Required cause groups are genetic, environmental, nutritional and cancer.
- A risk factor changes probability; it does not guarantee an outcome.
- Causes must be connected to biological effects.
Year 12 Biology
Module 8 · IQ2
⏱ ~45 min
Practice bank · 3 Short Answer
Lesson 6 of 21
What Causes Non-infectious Disease?
Non-infectious diseases are not spread by pathogens. Their causes can be genetic, environmental, nutritional or a combination of factors. Learn how to classify a cause and explain its effect.
Today's hook: A century ago, most Australians died of infectious diseases; today the overwhelming majority die of non-infectious ones like heart disease, cancer, and dementia. What drove this complete reversal in what Australians die from?
0/5TASKS
Warm up first
Three quick questions from earlier lessons. Pulling old material back to mind before you learn something new makes the new material stick better, so this is not busywork.
Worksheets
Practise this lesson
Four printable worksheets that build from the foundations up to exam-style questions, start at whatever level suits you.
Lesson map
From cause to effect
First separate infectious from non-infectious disease. Then classify causes and build a clear biological explanation.
- 1Identify the disease type.Ask whether a pathogen causes and can transmit the disease.
- 2Classify the contributing factor.Use genetic, environmental, nutritional or multifactorial.
- 3Link cause to effect.Explain the biological change and its consequence.
Know what matters
- Many diseases are multifactorial.
- Incidence counts new cases; mortality concerns deaths.
- Population data can reveal disease patterns.
- How ageing and control of infection changed population disease patterns.
- Why association alone does not prove causation.
- How protective factors can reduce risk.
0
Predict first: disease or risk?
connectA person smokes for many years but never develops lung cancer. Which conclusion is most accurate?
1
Key vocabulary, translated
vocabNon-infectiousnot spread between hosts by a pathogen
Risk factorfactor linked to a higher chance of disease
Multifactorialinfluenced by several interacting factors
Incidencenew cases in a population over a time period
Mortalitydeaths in a population
True or false: non-infectious means the disease cannot have any genetic cause.
2
Classify the main contributing factor
applyGenetic
A DNA variant changes a protein or biological process. Example: a CFTR variant contributing to cystic fibrosis.
Environmental
An external exposure damages cells or organs. Example: ultraviolet radiation damaging skin-cell DNA.
Nutritional
Deficiency, excess or imbalance affects function. Example: inadequate iron reducing haemoglobin production.
Cancer is uncontrolled cell division caused by accumulated changes in cell-cycle control. Genetic susceptibility and environmental exposure can both contribute.
Build an explanation+7 XP
Put the reasoning steps in a useful exam order.
- Describe the effect on cells, tissues or organs.
- Identify the disease as non-infectious.
- Link the effect to signs, symptoms or disease risk.
- State the biological change caused by that factor.
- Classify the main contributing factor.
3
Worked example: more than one factor
explainType 2 diabetes is multifactorial. Genetic susceptibility can affect how the body controls glucose, while diet, physical activity, sleep, medicines and social conditions can change risk. No single factor explains every case.
HSC exam move
Use cautious causal language: “increases risk by…” or “contributes to…” unless the evidence supports a direct cause. Then name the biological effect.
4
Choose your route
differentiateUse the frame to explain one example.
Explain why one disease may be described as multifactorial.
A graph shows disease incidence rising with exposure. Explain what it supports and what it cannot prove alone.
5
Exit check
retrieveMemorise
Genetic, environmental, nutritional, cancer, risk factor.
Understand
Risk changes probability; multifactorial diseases have interacting influences.
Apply
Classify a factor and link it to a biological effect.
Avoid
Do not claim that one risk factor guarantees disease.
01
Multiple Choice
+5 XP
A fresh set drawn from this lesson's question bank, feedback shown immediately. +5 XP per correct · +25 XP all correct
Pick your answer, then rate your confidence, that tells the system what to drill next.
02
Short Answer, 14 marks
+5 XP
ApplyBand 3–4(4 marks) 1. Identify and classify two non-infectious diseases from different categories, providing the primary cause and one specific example of how that cause leads to disease at the cellular or molecular level.
AnalyseBand 4–5(5 marks) 2. Explain why non-infectious diseases now cause more deaths in Australia than infectious diseases. Refer to specific AIHW data, the epidemiological transition, and at least two factors that contributed to the shift.
EvaluateBand 5–6(5 marks) 3. Type 2 diabetes is often described as a 'lifestyle disease.' Evaluate the accuracy of this description by analysing the genetic, environmental, nutritional, and socioeconomic factors that contribute. Conclude by explaining whether the label is useful, misleading, or both.
Show all answers
Multiple choice
MC answers and full explanations are shown inline as you complete each question. Use the retry button to attempt a fresh set from the lesson bank.
Short Answer Model Answers
SA1 (4 marks): Disease 1, Cystic fibrosis (genetic): autosomal recessive CFTR mutation (commonly F508del) causes the CFTR chloride channel to misfold and be degraded before reaching the membrane; without functional Cl⁻ channels, chloride and water cannot be secreted into airways → thick mucus → chronic infection and malabsorption [2]. Disease 2, Melanoma (cancer with environmental cause): UV radiation causes thymine dimers in skin-cell DNA, disrupting tumour suppressors (e.g. CDKN2A/p16) and proto-oncogenes (e.g. BRAF); accumulated mutations disrupt cell-cycle checkpoints → uncontrolled melanocyte division → malignant melanoma [2].
SA2 (5 marks): AIHW: CHD is the leading cause of death (~10% of deaths), followed by dementia, cerebrovascular disease, lung cancer, COPD, all non-infectious; infectious disease is not in the top five [1]. Epidemiological transition: the 20th-century shift from infectious to non-infectious disease as the dominant cause of mortality as infectious-disease deaths fell [1]. Factor 1, infectious-disease control: antibiotics, vaccination, sanitation and better nutrition reduced deaths from TB, pneumonia and childhood infections, so people survive to develop NID [1.5]. Factor 2, ageing populations: life expectancy rose from ~55 (1900) to ~83, so far more Australians reach the ages at which CHD, dementia and cancer manifest [1.5].
SA3 (5 marks): Genetic: strong heritable component, first-degree relatives have 2–3× risk; some ethnic groups (Indigenous Australians, South Asian, Pacific Islander) have higher genetic susceptibility, a baseline that cannot be changed by lifestyle [1]. Environmental: physical inactivity and sedentary work, strongly shaped by socioeconomic conditions (access to safe exercise spaces) [1]. Nutritional: chronic excess refined carbohydrate/saturated fat → hyperinsulinaemia, beta-cell exhaustion, insulin resistance; central obesity → inflammation impairing insulin signalling [1]. Socioeconomic: T2D is more prevalent in lower-income, regional and Indigenous populations with less access to fresh produce and preventive healthcare, and higher financial stress [1]. Evaluation: the 'lifestyle disease' label is partially accurate (lifestyle factors are important modifiable risks and the basis of treatment) but misleading because it implies the disease is purely personal choice, ignoring genetic predisposition and socioeconomic determinants, and it can drive stigma. Most accurate: a multifactorial non-infectious disease in which lifestyle factors are important but not solely determinative [1].
Check what actually stuck
Take the full module quiz
quiz
A full module quiz covering every lesson in this module, not just this one. Set aside a decent block of time and treat it like a real assessment.
Start the module quiz →FINAL BOSS
Boss Battle, Causes of Non-Infectious Disease
Take on the boss-battle arena for this lesson, rapid-fire questions on disease classification and risk factors.
How did your thinking change?
Return to your Think First responses and connect them to the ABS 2023 Causes of Death report. In 1900, Australia's top 3 killers were all infectious (pneumonia, TB, diarrhoeal disease); by 2022, 89% of deaths were non-infectious (cardiovascular disease 27%, cancer 25%, dementia 10%), and life expectancy rose from 55 to 83 years. This epidemiological transition, which took approximately 50 years (1940–1990), is the statistical backdrop to everything in Module 8.
- Q1, your disease list: Can you now classify every disease you listed into one of the four categories (genetic, environmental, nutritional, cancer)? Are any multifactorial? Were any actually infectious that you initially listed as non-infectious?
- Q2, risk factors: State precisely, using the terminology: risk factor, multifactorial disease, genetic predisposition, environmental exposure. Explain why the ABS data shows risk factors associated with a disease category but does not prove individual causation.
- Write one sentence explaining the epidemiological transition, why the ABS 2023 shift to 89% non-infectious deaths reflects social and medical progress rather than a worsening of those diseases.