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30 HSC Biology practice questions for 2026 (Modules 5-8)

HSCBiologyStudy guide14 min read

30 HSC Biology practice questions modelled on past NESA exam patterns. Grouped by module (Heredity, Genetic Change, Infectious Disease, Non-infectious Disease and Disorders). Use these under timed conditions.

Jump to a section
  1. How to use this question bank
  2. Module 5: Heredity (1-7)
  3. Module 6: Genetic Change (8-13)
  4. Module 7: Infectious Disease (14-21)
  5. Module 8: Non-infectious Disease and Disorders (22-30)
  6. Marking your own work
  7. Past papers
  8. Related guides
  9. Check your knowledge

How to use this question bank

HSC Biology is a 3-hour exam covering four Year 12 modules. These 30 practice questions span the modules and are modelled on past NESA paper patterns.

Three rules for HSC Biology practice:

  1. Use named examples. Every extended response should reference at least one specific named pathogen, disease, technology, or organism. Generic answers score in the middle band.
  2. Show your structure. Extended responses are marked for structure as much as content. Use paragraph breaks and clear topic sentences.
  3. Draw diagrams. Many marks are reserved for labelled diagrams (the immune response, replication, a feedback loop). Draw them confidently.

Module 5: Heredity (1-7)

  1. Explain how the process of meiosis generates genetic variation in offspring.

  2. Describe the process of DNA replication, including the role of DNA polymerase. (4 marks)

  3. Distinguish between transcription and translation. Include the location and key enzymes for each. (5 marks)

  4. Using a Punnett square, predict the genotype and phenotype ratios for a cross between two parents heterozygous for cystic fibrosis (Cc x Cc). (3 marks)

  5. Haemophilia is a sex-linked recessive disorder. A carrier mother and an unaffected father have children. Use a Punnett square to determine the probability that a male offspring is affected. (4 marks)

Sex-linked Punnett square reference (haemophilia carrier mother by unaffected father) A 2-by-2 Punnett square for the cross of a carrier mother X big-N X little-n with an unaffected father X big-N Y. The four offspring genotypes are X big-N X big-N (unaffected daughter), X big-N X little-n (carrier daughter), X big-N Y (unaffected son), and X little-n Y (affected son). The affected-son cell is highlighted in the accent colour. One quarter of all offspring (one half of sons) are affected. XN Xn XN Y XNXN XNXn XNY XnY unaffected ♀ carrier ♀ unaffected ♂ affected ♂ ¼ of all offspring affected; ½ of sons affected. Carrier mother × unaffected father.
Sex-linked Punnett reference for Q5: carrier mother (XNXn) crossed with unaffected father (XNY) yields half of sons affected (accent cell).

  1. Compare and contrast Mendelian inheritance and polygenic inheritance, using a named example for each. (6 marks)

  2. Describe one application of DNA profiling. Evaluate the ethical implications of its use. (7 marks)

Module 6: Genetic Change (8-13)

  1. Distinguish between a point mutation and a chromosomal mutation. Use a named example for each. (4 marks)

  2. Explain how environmental mutagens can cause genetic change, with a named example. (4 marks)

  3. Describe the process of producing recombinant DNA, using insulin production as a named example. (6 marks)

  4. CRISPR-Cas9 is a genetic engineering technology. Describe how it works AND evaluate its potential medical applications. (8 marks)

  5. Explain how genetic change drives evolution. Use a named example to illustrate. (5 marks)

  6. Compare two biotechnologies used in agriculture (e.g. transgenic crops and selective breeding) in terms of effectiveness, ethical considerations, and ecological impact. (8 marks)

Module 7: Infectious Disease (14-21)

  1. Describe one named bacterial disease and one named viral disease, including their transmission, symptoms, and treatment. (6 marks)

  2. Explain the role of phagocytosis in the innate immune response. (4 marks)

  3. Describe the role of B lymphocytes and T lymphocytes in the adaptive immune response. (6 marks)

  4. With reference to a named vaccine, explain how vaccination produces long-term immunity. (6 marks)

  5. Define R0 (basic reproductive number). Using a named infectious disease as an example, explain how public health measures can reduce R0. (6 marks)

  6. Antibiotic resistance is increasing globally. Explain how resistance develops and discuss strategies to slow its spread. (7 marks)

  7. Compare the innate (non-specific) and adaptive (specific) immune responses. Include at least two points of difference. (5 marks)

  8. Plasmodium causes malaria. Describe the role of the Anopheles mosquito in malaria transmission AND outline two public health strategies for malaria control. (7 marks)

Module 8: Non-infectious Disease and Disorders (22-30)

  1. Define homeostasis. Using thermoregulation as an example, describe the components of a homeostatic feedback loop. (6 marks)
Negative feedback loop reference (thermoregulation) A closed loop showing the four components of a homeostatic feedback. A set point of 37 degrees Celsius sits at the top. A stimulus (rising body temperature) feeds into temperature receptors in the skin and hypothalamus. The hypothalamus acts as the control centre. Effectors (sweat glands and skin blood vessels) produce a response (evaporative cooling and vasodilation). The negative feedback arrow returns to the set point with a minus sign indicating that the response opposes the stimulus. Set point core T ≈ 37 °C 2. Receptor thermoreceptors 4. Effector sweat, vasodilation 3. Control centre hypothalamus 1. stimulus (rising T) signal response − Receptor detects deviation; the effector response opposes it, returning the system to set point.
Negative-feedback reference for Q22: set point, receptor, control centre, effector, and the return arrow (accent colour, (−) badge) showing that the effector response opposes the original stimulus.

  1. Explain how blood glucose levels are regulated after a meal. Include the roles of insulin and the pancreas. (5 marks)

  2. Type 1 and Type 2 diabetes are both disorders of blood glucose regulation but have different causes. Distinguish between them and outline management strategies for each. (7 marks)

  3. Describe the role of the kidney in osmoregulation, including the role of ADH. (5 marks)

  4. Explain how a named environmental factor causes a specific non-infectious disease. Evaluate prevention strategies. (7 marks)

  5. Compare a genetic disease and a nutritional disease in terms of causes, symptoms, prevention, and treatment. Use specific named examples. (8 marks)

  6. Cataracts are a disorder of vision. Describe the cause of cataracts AND outline the technology used to treat them. (5 marks)

  7. Cardiovascular disease is a leading cause of death in Australia. Describe two major risk factors AND evaluate public health interventions to address them. (8 marks)

  8. Evaluate the use of two different technologies in diagnosing a specific non-infectious disease (your choice of disease). (8 marks)

Marking your own work

For each question:

  • 2-3 marks: short answer. One paragraph. One named example.
  • 4-6 marks: medium response. Two paragraphs. Named examples plus a clear concept explanation.
  • 7-9 marks: extended response. Three-four paragraphs with structure, named examples, evaluation, and (for relevant questions) a labelled diagram.

A useful self-mark question: did I name a specific pathogen / technology / disease / scientist? If yes, you usually scored in the higher band.

Past papers

These practice questions complement past NESA exam papers; they do not replace them. NESA publishes papers and marking guides at educationstandards.nsw.edu.au. Aim for 6-8 full past papers under timed 3-hour conditions in Term 4.

These questions are written by ExamExplained for practice purposes only. They are not endorsed by NESA.

Check your knowledge

A mix of definitional, calculation/explanation, and exam-style multi-part questions covering this topic. Aim to answer all under exam conditions, then check against the solutions block.

  1. Define gene expression and outline the two main stages by which genetic information in DNA is translated into a functional protein. (3 marks)
  2. A pedigree (described in words) shows: Generation I has affected father and unaffected mother; Generation II shows two children, one affected and one unaffected; the affected child of Generation II marries an unaffected partner and has two children in Generation III, one affected and one unaffected. (a) Identify the most likely mode of inheritance. (b) State the genotype of all individuals using AA for the dominant allele and aa for the recessive. (c) Calculate the probability that a future child of the Generation II affected individual will be affected. (5 marks)
  3. The table records the prevalence of cystic fibrosis carriers in five Australian populations (CF allele frequency qq): Anglo-Celtic 0.025; Greek 0.018; Lebanese 0.012; Aboriginal and Torres Strait Islander 0.005; Chinese 0.005. Using the Hardy-Weinberg principle (carrier frequency ≈2q\approx 2q): (a) Calculate the carrier frequency in the Anglo-Celtic population. (b) Calculate the affected (q2q^2) frequency. (c) Comment on why prenatal screening targets the Anglo-Celtic population most strongly. (4 marks)
  4. (a, 3) Describe the structure of an antibody (IgG) with reference to its heavy and light chains, the variable and constant regions, and the antigen-binding site. (b, 3) Explain how clonal selection ensures that the immune system produces antibodies specific to a single antigen. (c, 2) Discuss one named monoclonal antibody therapy used in Australia, with reference to its target. (8 marks)
  5. A NSW cohort study tracks Type 2 diabetes incidence in two populations over 10 years: (i) Group A is a sedentary urban Sydney population with average BMI = 31, daily steps = 3,200, weekly exercise = 0 hours: incidence = 1,800 per 100,000 per year; (ii) Group B is a rural NSW population with average BMI = 25, daily steps = 9,500, weekly exercise = 4 hours: incidence = 350 per 100,000 per year. (a) Calculate the relative risk in Group A vs Group B. (b) State three modifiable lifestyle factors that the data suggest contribute to the difference. (c) Discuss one limitation of cohort studies in establishing causation. (6 marks)
  6. (a) Explain the principle of the polymerase chain reaction (PCR) including the role of denaturation, annealing, and extension. (b) Calculate the number of copies of a target DNA sequence produced from a single template molecule after 25 cycles, assuming 100 percent efficiency. (c) State two practical uses of PCR in Australian clinical or forensic laboratories. (5 marks)
  7. Compare a transgenic organism and a gene-edited (e.g. CRISPR) organism. Address (a) the source of the inserted/modified DNA, (b) the precision and predictability of the change, (c) the regulatory framework in Australia, and (d) one named example of each. (6 marks)
  8. The Murray-Darling cod (Maccullochella peelii) has experienced significant population decline due to habitat loss, river regulation, and overfishing. Researchers at the NSW Department of Primary Industries propose a captive breeding and re-stocking program combined with genetic monitoring to maintain biodiversity. (a, 3) Explain how meiosis and sexual reproduction maintain genetic variation in wild populations, and why this matters for long-term species survival. (b, 3) Describe how DNA profiling could be used to monitor the genetic diversity of captive-bred fish and ensure that re-stocking does not reduce overall heterozygosity. (c, 4) Evaluate the use of biotechnology (selective breeding, cryopreservation of sperm, or CRISPR-based disease resistance) in conserving an Australian threatened species, addressing benefits, risks, and one ethical consideration. (10 marks)
Solutions
Q1
Gene expression is the process by which the information encoded in a gene's DNA sequence is converted into a functional product, usually a protein. The two main stages are: (i) transcription - RNA polymerase reads the DNA template strand in the nucleus and synthesises a complementary mRNA molecule, which undergoes processing (5' cap, 3' poly-A tail, splicing); (ii) translation - the mRNA exits the nucleus and is read at the ribosome in triplets (codons), where tRNAs deliver corresponding amino acids that are joined into a polypeptide. The polypeptide then folds into a functional protein.
Q2
(a) The pattern (affected father with affected children in two generations, no skipping of generations, both sexes affected) is consistent with autosomal dominant inheritance. (b) Generation I: father AaAa, mother aaaa. Generation II: affected child AaAa, unaffected child aaaa. Spouse of affected child: aaaa. Generation III: affected child AaAa, unaffected child aaaa. (c) The affected Generation II individual is heterozygous AaAa crossed with aaaa spouse; Punnett square gives 50 percent AaAa (affected) and 50 percent aaaa (unaffected). Probability a future child is affected = 0.50.
Q3
(a) Carrier frequency ≈2q=2×0.025=0.05=5\approx 2q = 2 \times 0.025 = 0.05 = 5 percent. (b) Affected frequency q2=(0.025)2=6.25×10−4q^2 = (0.025)^2 = 6.25 \times 10^{-4}, that is approximately 1 in 1,600 births. (c) The Anglo-Celtic population has the highest allele frequency (about 5 times that of Aboriginal or Chinese populations), so the highest detection rate for prenatal screening relative to cost. Screening programs are targeted at populations where the disease frequency justifies the expense and emotional burden of testing.
Q4
(a) IgG is a Y-shaped molecule of approximately 150 kDa. Two heavy chains (about 50 kDa each) and two light chains (about 25 kDa each) are linked by disulfide bonds. Each chain has a variable region (V) at the N-terminus and a constant region (C) at the C-terminus. The two antigen-binding sites (one at each arm of the Y) are formed by the variable regions of one heavy chain and one light chain combined, with hypervariable complementarity-determining regions (CDRs) that contact the antigen. The constant region (Fc) at the stem of the Y mediates effector functions (complement activation, binding to phagocytes). (b) Clonal selection: the body contains millions of B cells, each carrying a distinct B-cell receptor on its surface. When an antigen enters the body, only the few B cells whose receptors match the antigen are stimulated to proliferate and differentiate into plasma cells (producing antibodies of identical specificity) and memory B cells. This ensures the antibody response is specific to the encountered antigen. (c) Trastuzumab (Herceptin) is used in Australia (PBS-listed) for HER2-positive breast cancer. It is a humanised monoclonal antibody targeting the HER2 receptor on cancer cells, blocking growth signalling and marking the cells for immune destruction. The 5-year survival rate for HER2-positive breast cancer has improved significantly with this therapy.
Q5
(a) Relative risk = 1800 / 350 = 5.14. People in Group A are approximately 5 times more likely to develop Type 2 diabetes per year than those in Group B. (b) Three modifiable factors: (i) physical inactivity (low daily steps and zero exercise) - exercise increases insulin sensitivity; (ii) elevated BMI (31 vs 25) - excess adipose tissue, particularly visceral fat, produces inflammatory cytokines that promote insulin resistance; (iii) likely dietary patterns associated with sedentary urban lifestyle (e.g. higher refined carbohydrate and saturated-fat intake) - though not directly measured. (c) Cohort studies establish correlation, not causation: confounding variables (socio-economic status, genetic predisposition, dietary habits, access to healthcare) may differ between the urban and rural populations independent of the exercise and BMI variables measured. Randomised controlled trials are needed to establish a causal link between specific interventions (e.g. an exercise program) and reduced diabetes incidence.
Q6
(a) PCR amplifies a specific DNA sequence through repeated cycles of three temperature-controlled steps. Denaturation (95 degrees C) separates the double-stranded DNA into single strands. Annealing (50 to 65 degrees C) allows short DNA primers (specific to the flanking sequences) to bind to each single strand. Extension (72 degrees C) allows a thermostable DNA polymerase (Taq polymerase from Thermus aquaticus) to extend the primers, synthesising a complementary strand. Each cycle doubles the target. (b) After nn cycles, the number of copies =2n= 2^n. After 25 cycles: 225=3.36×1072^{25} = 3.36 \times 10^7, that is approximately 33.6 million copies from a single template. (c) Practical uses: (i) clinical diagnostics - detection of pathogen DNA/RNA in patient samples (SARS-CoV-2 RT-PCR testing at NSW Health Pathology, hepatitis B viral load monitoring); (ii) forensic identification - amplification of STR loci from crime scene samples for matching against the NSW DNA Database.
Q7
(a) A transgenic organism contains DNA from a different species, inserted at a random or semi-random location in the genome (e.g. Bt corn contains a bacterial Bacillus thuringiensis gene). A gene-edited organism has its own DNA modified at a precise location using a programmable nuclease (e.g. CRISPR-Cas9); no foreign DNA is added in many edits. (b) Transgenesis is less precise: insertion may disrupt host genes (positional effects). CRISPR is highly precise (guide-RNA-directed), though off-target cleavage remains a small risk. (c) Australia: transgenic crops are regulated by the OGTR (Office of the Gene Technology Regulator) under the Gene Technology Act 2000; food products go through FSANZ. Since 2019 OGTR amendments, CRISPR edits that produce SDN-1 changes (no template, simple cuts repaired by NHEJ) are exempt from GMO regulation, reducing regulatory burden. (d) Transgenic example: GM cotton (Bollgard 3) carrying Bt genes for insect resistance, grown widely in NSW and Queensland. CRISPR example: gene-edited wheat varieties (Australian research) for fungal-disease resistance; not yet in commercial release.
Q8
(a) Meiosis generates genetic variation through (i) crossing over during prophase I, which exchanges segments between non-sister chromatids of homologous chromosomes; (ii) independent assortment during metaphase I, randomising which member of each homologous pair faces which pole; and (iii) random fusion of gametes at fertilisation. The resulting genetic variation in offspring is the raw material on which natural selection acts. For Murray-Darling cod, high heterozygosity buffers populations against environmental change, disease, and inbreeding depression - low-diversity populations have reduced fitness and elevated extinction risk. (b) DNA profiling using microsatellite (STR) markers can quantify allele frequencies and heterozygosity in captive and re-stocked populations. Periodic profiling of breeding adults and a sample of released juveniles allows the program to (i) avoid pairing closely related individuals (minimising inbreeding); (ii) detect loss of rare alleles over generations; (iii) measure the genetic similarity between captive and remaining wild populations to ensure re-stocked fish reflect natural diversity rather than a captive-selected subset. (c) Biotechnology evaluation. Selective breeding of cod for desirable traits (e.g. faster growth) risks reducing genetic diversity if performed without managing effective population size, but is well-established in Australian aquaculture. Cryopreservation of sperm (and increasingly eggs and embryos) provides a "genetic insurance policy": frozen samples from genetically diverse wild fish can be used to refresh captive populations and is non-invasive once collected. CRISPR-based disease resistance (e.g. resistance to chytrid fungus in frogs, a parallel Australian example) could mitigate a major threat but raises concerns about unintended ecological effects of gene-edited individuals released into wild populations and the risk of accelerating evolutionary change. Ethical consideration: traditional ecological knowledge of Aboriginal nations along the Murray-Darling (including the Barkindji, Ngarrindjeri and others) must inform conservation programs, particularly for culturally significant species. The AIATSIS Code of Ethics requires free, prior and informed consent from Traditional Owners for research conducted on or affecting their Country. Overall, biotechnology can support but not replace habitat restoration; an integrated approach combining cryopreservation, careful selective breeding, DNA monitoring, environmental flows, and Indigenous co-management offers the most robust path to species recovery.

Sources & how we know this

Based on the official NESA syllabus and published NESA past papers and marking guidelines. Not yet individually reviewed by a person; always check NESA and your school's materials for current rules.

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