Skill Align HSC Biology - Free Online Pack 0
A complete independently authored HSC Biology practice paper with worked answers and question-specific marking guidance.
- Paper
- Question and Answer Book
- Reading
- 5 minutes
- Writing
- 3 hours
- Assessment
- 100 marks
NESA-approved calculators may be used.
Section I: Objective-response questions
Attempt Questions 1-20. Allow about 35 minutes for this section. Select the alternative A, B, C or D that best answers each question.
Question 1
1 mark- More than one codon can specify the same amino acid.
- One codon can specify several different amino acids.
- The ribosome reads a codon in either nucleotide direction.
- A changed codon is removed from the mature mRNA as an intron.
Question 2
1 mark- The microorganism is sufficient by itself to cause the disease.
- Healthy plants are immune because they carry the microorganism.
- Association has been observed, but the microorganism has not yet been shown to cause the disease.
- The microorganism is excluded as a contributing cause.
Question 3
1 mark- 5'-UAC GGU AAA-3'
- 5'-AUG CCA UUU-3'
- 5'-ATG CCA TTT-3'
- 3'-AUG CCA UUU-5'
Question 4
1 mark- Secrete glucagon when blood glucose falls
- Detect glucose concentration in pancreatic capillaries
- Increase the sensitivity of muscle cells to insulin
- Secrete insulin in response to rising blood glucose
Question 5
1 mark- Exposure induces a resistance allele in susceptible adults.
- Resistant insects leave a greater proportion of the offspring under insecticide exposure.
- Repeated spraying increases resistance through use and disuse.
- The resistance frequency changes by random drift with no fitness difference.
Question 6
1 mark- It lacks the independent cellular machinery required for replication and protein synthesis.
- The viral genome cannot be copied because agar contains no DNA bases.
- The virus uses binary fission after absorbing agar nutrients.
- The viral capsid prevents its genome from being expressed outside an animal nucleus.
Question 7
1 mark- Skin-cancer incidence differs between families without measuring UV exposure.
- A cross-sectional survey links recent sunburn with existing lesions.
- Tumours from exposed groups contain mutations but no comparison group is included.
- Incidence is higher in otherwise comparable groups with greater cumulative UV exposure.
Question 8
1 mark- Autosomal dominant inheritance with complete penetrance
- Y-linked inheritance
- Autosomal recessive inheritance
- Mitochondrial inheritance from the father
Question 9
1 mark- Antigen-specific plasma cells dominate the first minutes of the response.
- Local vasoconstriction prevents immune cells entering the tissue.
- Local vasodilation increases blood flow and immune-cell access.
- Complement activation first rebuilds the damaged skin barrier.
Question 10
1 mark- Prevalence
- Incidence
- Case fatality
- Life expectancy
Question 11
1 mark- Any one of many genetically different sperm may fuse with the ovum.
- Crossing over occurs when the sperm enters the ovum.
- Independent assortment begins after the zygote starts mitosis.
- The ovum selects a sperm carrying alleles unlike its own.
Question 12
1 mark- It cuts genomic DNA at specific recognition sequences.
- It separates DNA fragments according to length in an electric field.
- It amplifies inserted DNA without entering a host cell.
- It can carry inserted DNA and replicate inside a bacterial cell.
Question 13
1 mark- Secretion of erythropoietin to stimulate red-cell production
- Release of renin to contribute to blood-pressure regulation
- Adjustment of water reabsorption in functioning nephrons
- Removal of urea and excess ions from the blood
Question 14
1 mark- Each chromosome must be copied during the S phase.
- DNA replication occurs during G2 immediately before mitosis.
- Homologous chromosomes pair before a mitotic division.
- Chromosome number is reduced before mitotic anaphase.
Question 15
1 mark- They currently occupy habitats with the same temperature.
- They have equal numbers of chromosomes.
- Their amino-acid sequences differ at the fewest positions.
- Their adults have similar body mass.
Question 16
1 mark- Plasma cells retained from the first dose account for the complete secondary response.
- Antigen-specific memory lymphocytes formed after the first dose
- Non-specific phagocytes acquire an antigen-specific receptor after the first dose.
- Vaccine antigen remains unchanged in epithelial cells until the booster.
Question 17
1 mark- Non-sister chromatids of homologous chromosomes
- Sister chromatids of the same replicated chromosome
- Two unrelated chromosomes at metaphase II
- Maternal and paternal gametes after fertilisation
Question 18
1 mark- Artificial selection
- Convergent evolution
- Stabilising selection
- Founder-effect genetic drift
Question 19
1 mark- Case numbers are stable because each case replaces itself.
- Each case produces fewer than one new case on average, so transmission is declining.
- Transmission is increasing slowly because some cases infect two people.
- Prevalence must already have reached zero.
Question 20
1 mark- It confirms a diagnosis without any follow-up testing.
- It prevents the biological onset of disease in everyone screened.
- It can identify disease or elevated risk before symptoms prompt clinical diagnosis.
- It ensures that treatment benefits outweigh false-positive harms.
Section II: Written-response questions
Attempt Questions 21-40. Allow about 2 hours and 25 minutes for this section. Show relevant working and support conclusions with biological evidence.
Question 21
2 marksA substitution changes one DNA base in a protein-coding gene.
Question 22
2 marksAt a camp, 36 of 90 people who ate a cold dessert became ill, compared with 6 of 60 people who did not eat it.
Question 23
4 marksA gene's DNA template sequence is 3'-TAC GGA CTT-5'. Use the supplied mRNA codon reference.
Question 24
2 marksBlood glucose rises after a meal in a person without diabetes.
Question 25
3 marksA beetle population initially contains rare resistance alleles. After six spraying seasons, resistant beetles make up 74% of the population.
Question 26
3 marksA cut becomes warm, red and swollen within hours of bacterial entry.
Question 27
3 marksA cohort study reports a higher lung-cancer incidence among smokers than non-smokers, with risk increasing across categories of cumulative cigarette exposure.
Question 28
4 marksAlbinism in a family is caused by an autosomal recessive allele. Two unaffected parents have one affected child.
Question 29
4 marksMean antibody concentration after dose 1 was 8 units at day 14 and 22 units at day 28. After a booster at day 180, it was 58 units at day 194 and 71 units at day 208.
Question 30
4 marksA patient has a persistently low estimated glomerular filtration rate, high blood urea and ankle swelling.
Question 31
7 marksA couple who both carry a cystic-fibrosis allele are considering IVF with preimplantation genetic testing (PGT). The test samples a small number of embryo cells and does not detect every possible genetic or developmental condition.
Question 32
4 marksTwo whale species share a vestigial pelvic structure, similar early embryos and 98.7% identity across several homologous DNA sequences.
Question 33
4 marksA screening test is used in 1000 people. Of 100 people who truly have the disease, 90 test positive. Of 900 without disease, 135 test positive.
Question 34
2 marksAn onion root-tip cell contains 16 chromosomes in G1.
Question 35
7 marksResearchers propose using CRISPR-Cas9 to alter a salt-response regulator in tomatoes. Greenhouse trials show higher fruit yield in salty soil, but only one edited line was tested and three predicted off-target sites were checked.
Question 36
4 marksA school reports 43 respiratory infections after a crowded indoor event. Investigators know who attended but have incomplete vaccination and prior-infection records.
Question 37
3 marksPurple flowers are dominant to white flowers. A heterozygous purple plant is crossed with a white plant, and 82 purple and 78 white offspring are produced.
Question 38
4 marksA DNA profile shows child bands at 120, 180, 260 and 310 base pairs. The mother has 120, 210, 260 and 340; candidate X has 150, 180, 290 and 310; candidate Y has 140, 200, 280 and 330.
Question 39
7 marksA region's two-dose measles vaccination coverage has fallen from 95% to 84%. Cases are concentrated in several communities with limited clinic access and high online misinformation.
Question 40
7 marksA community has rising type 2 diabetes incidence, limited access to fresh food, few safe exercise spaces and long waits for primary care. Adults already diagnosed show varied glucose control.
Worked Solutions And Marking Guide
General marking principles
- Award credit for scientifically accurate equivalent wording and logically equivalent calculations.
- Apply discrete criteria only to independently assessable operations; apply quality bands to integrated analytical and extended responses.
- Use indicative content as examples rather than an exhaustive checklist, and do not infer an unstated causal mechanism from association alone.
Section I: Objective-response questions Question 1
Answer: More than one codon can specify the same amino acid.
The genetic code is degenerate, so some substitutions produce a synonymous codon. The alternatives reverse codon specificity, ignore the fixed 5'-to-3' reading direction, or confuse a translated codon with RNA splicing.
Section I: Objective-response questions Question 2
Answer: Association has been observed, but the microorganism has not yet been shown to cause the disease.
Occurrence in both groups does not establish causation; isolation and controlled infection evidence would be needed. Finding the organism in both groups proves neither sufficiency nor protection and does not exclude a conditional causal role.
Section I: Objective-response questions Question 3
Answer: 5'-AUG CCA UUU-3'
The mRNA matches the DNA coding strand in the 5' to 3' direction, with uracil replacing thymine. UAC GGU AAA is the complementary sequence rather than the coding-strand transcript, ATG CCA TTT retains DNA thymine, and 3'-AUG CCA UUU-5' reverses the required mRNA direction.
Section I: Objective-response questions Question 4
Answer: Secrete insulin in response to rising blood glucose
Beta cells make insulin, which supports cellular glucose uptake and storage after blood glucose rises. Alpha cells secrete glucagon, glucose sensing alone is not the lost output, and target-cell sensitivity is distinct from beta-cell insulin secretion.
Section I: Objective-response questions Question 5
Answer: Resistant insects leave a greater proportion of the offspring under insecticide exposure.
The insecticide is a selection pressure that changes relative survival and reproductive success. The alternatives invoke directed mutation, inheritance of an acquired change, or drift despite the stated survival difference.
Section I: Objective-response questions Question 6
Answer: It lacks the independent cellular machinery required for replication and protein synthesis.
Viruses depend on host-cell enzymes, ribosomes, energy and raw materials to replicate. Agar can supply chemicals but not living translation machinery; viruses do not divide by binary fission, and some replicate outside a nucleus.
Section I: Objective-response questions Question 7
Answer: Incidence is higher in otherwise comparable groups with greater cumulative UV exposure.
A consistent exposure-response association, after controlling major confounders, supports UV as a risk factor. Family differences, unclear timing and an absent comparison group are weaker evidence than a controlled exposure-response association.
Section I: Objective-response questions Question 8
Answer: Autosomal recessive inheritance
Two heterozygous unaffected parents can each transmit a recessive allele to sons or daughters. Complete-penetrance autosomal dominance normally requires an affected parent, a Y-linked trait cannot affect a daughter, and mitochondrial traits are not transmitted by an affected father.
Section I: Objective-response questions Question 9
Answer: Local vasodilation increases blood flow and immune-cell access.
Inflammatory mediators promote vasodilation and recruitment of innate immune cells. The alternatives confuse a later adaptive response, reverse the vascular change, or assign tissue repair as the initiating defence.
Section I: Objective-response questions Question 10
Answer: Incidence
Incidence counts new cases arising in a defined population over a stated period. Prevalence counts existing cases, case fatality measures deaths among diagnosed cases, and life expectancy estimates expected years of life; none is the count of new diagnoses over the year.
Section I: Objective-response questions Question 11
Answer: Any one of many genetically different sperm may fuse with the ovum.
Random union samples independently assorted and recombined gametes, producing different allele combinations. Crossing over and assortment occur during meiosis, while sperm-ovum fusion is random rather than genotype-directed.
Section I: Objective-response questions Question 12
Answer: It can carry inserted DNA and replicate inside a bacterial cell.
A plasmid can be cut, ligated to foreign DNA and copied as bacteria reproduce. Restriction enzymes cut DNA and electrophoresis separates it; plasmid copies depend on replication inside a host cell.
Section I: Objective-response questions Question 13
Answer: Removal of urea and excess ions from the blood
Dialysis uses diffusion across a membrane to remove selected wastes and correct fluid and ion imbalance. Dialysis removes dissolved wastes and excess ions but does not replace renal endocrine secretion or active nephron regulation.
Section I: Objective-response questions Question 14
Answer: Each chromosome must be copied during the S phase.
DNA replication in S phase produces sister chromatids that can be separated during mitosis. The alternatives misplace DNA replication, import homologue pairing from meiosis I, or confuse mitosis with reduction division.
Section I: Objective-response questions Question 15
Answer: Their amino-acid sequences differ at the fewest positions.
Fewer sequence differences are generally consistent with less time for mutations to accumulate since divergence. Similar habitat temperature or body mass can arise without close ancestry, while equal chromosome number is a coarse feature; sequence differences in homologous proteins directly compare inherited molecular change.
Section I: Objective-response questions Question 16
Answer: Antigen-specific memory lymphocytes formed after the first dose
Memory B and T cells respond more rapidly and strongly after renewed exposure to the same antigen. Long-lived memory lymphocytes, rather than persistent antigen or newly specific innate cells, account for the accelerated secondary response.
Section I: Objective-response questions Question 17
Answer: Non-sister chromatids of homologous chromosomes
Homologous chromosomes synapse in prophase I, allowing corresponding non-sister chromatids to exchange segments. Sister chromatids are copies of one chromosome, unrelated chromosomes do not synapse as homologous pairs, and gamete fusion occurs after meiosis; crossing over occurs between non-sister chromatids of homologues in prophase I.
Section I: Objective-response questions Question 18
Answer: Founder-effect genetic drift
A small, non-representative founder sample can establish allele frequencies by chance. Artificial selection requires human choice, convergent evolution concerns independently evolved similarity, and stabilising selection requires differential fitness; the immediate allele-frequency shift arises from chance sampling by the founders.
Section I: Objective-response questions Question 19
Answer: Each case produces fewer than one new case on average, so transmission is declining.
When the effective reproduction number stays below 1, chains of transmission tend to contract. A stable chain corresponds to a value near 1, growth to a value above 1, and declining transmission can precede zero prevalence.
Section I: Objective-response questions Question 20
Answer: It can identify disease or elevated risk before symptoms prompt clinical diagnosis.
Earlier detection can permit monitoring or treatment, although screening accuracy and follow-up still matter. Screening estimates risk or detects possible disease; confirmation, prevention and benefit-harm evaluation still require further evidence.
Section II: Written-response questions Question 21
Indicative answer: - The altered codon may remain synonymous and specify the same amino acid. - Alternatively, it may specify a different amino acid or a stop codon and change the polypeptide.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The altered codon may remain synonymous and specify the same amino acid.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Alternatively, it may specify a different amino acid or a stop codon and change the polypeptide.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 22
Indicative answer: - The attack rate among dessert eaters is 36/90 = 40%. - The attack rate among non-eaters is 6/60 = 10%.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The attack rate among dessert eaters is 36/90 = 40%.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The attack rate among non-eaters is 6/60 = 10%.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 23
Indicative answer: - The mRNA sequence is 5'-AUG CCU GAA-3'. - The first three amino acids are methionine–proline–glutamic acid (Met–Pro–Glu). - RNA polymerase synthesises complementary RNA from the DNA template during transcription. - The ribosome reads the mRNA codons during translation, while transfer RNAs supply the corresponding amino acids.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The mRNA sequence is 5'-AUG CCU GAA-3'.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The first three amino acids are methionine–proline–glutamic acid (Met–Pro–Glu).
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: RNA polymerase synthesises complementary RNA from the DNA template during transcription.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The ribosome reads the mRNA codons during translation, while transfer RNAs supply the corresponding amino acids.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 24
Indicative answer: - Pancreatic beta cells release insulin in response to the elevated blood glucose. - Insulin promotes glucose uptake and glycogen formation in target tissues, lowering blood glucose.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Pancreatic beta cells release insulin in response to the elevated blood glucose.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Insulin promotes glucose uptake and glycogen formation in target tissues, lowering blood glucose.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 25
Indicative answer: - Heritable resistance variation was already present or arose independently of need. - Spraying reduced the reproductive contribution of susceptible beetles relative to resistant beetles. - Surviving resistant beetles passed resistance alleles to offspring, increasing their frequency over generations.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Heritable resistance variation was already present or arose independently of need.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Spraying reduced the reproductive contribution of susceptible beetles relative to resistant beetles.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Surviving resistant beetles passed resistance alleles to offspring, increasing their frequency over generations.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 26
Indicative answer: - Damaged cells and immune cells release inflammatory signals that cause vasodilation and increased capillary permeability. - Greater blood flow and permeability deliver phagocytes and antimicrobial components to the damaged tissue. - Phagocytes recognise, engulf and digest bacteria non-specifically, while clotting helps limit spread.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Damaged cells and immune cells release inflammatory signals that cause vasodilation and increased capillary permeability.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Greater blood flow and permeability deliver phagocytes and antimicrobial components to the damaged tissue.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Phagocytes recognise, engulf and digest bacteria non-specifically, while clotting helps limit spread.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 27
Indicative answer: - The higher incidence and exposure-response gradient are consistent with smoking increasing risk. - Tobacco smoke contains mutagens that provide a plausible mechanism through accumulated DNA damage. - Observational groups may differ in other exposures, so confounding and bias must be assessed before a causal conclusion.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The higher incidence and exposure-response gradient are consistent with smoking increasing risk.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Tobacco smoke contains mutagens that provide a plausible mechanism through accumulated DNA damage.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Observational groups may differ in other exposures, so confounding and bias must be assessed before a causal conclusion.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 28
Indicative answer: - Both unaffected parents must be heterozygous carriers, Aa. - Each parent can contribute either A or a with probability one-half. - The cross Aa x Aa produces AA, Aa, Aa and aa genotype outcomes. - The probability of an affected aa child in each independent pregnancy is one-quarter, or 25%.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Both unaffected parents must be heterozygous carriers, Aa.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Each parent can contribute either A or a with probability one-half.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The cross Aa x Aa produces AA, Aa, Aa and aa genotype outcomes.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The probability of an affected aa child in each independent pregnancy is one-quarter, or 25%.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 29
Indicative answer: - At matched 14-day intervals, the booster response is higher: 58 units compared with 8 units after dose 1. - At matched 28-day intervals, the booster response is also higher: 71 units compared with 22 units. - The first dose activates antigen-specific lymphocytes and generates memory cells. - On re-exposure, memory cells undergo rapid clonal expansion and differentiation, producing a faster and larger antibody response.
Question-specific marking approach
Read the response as a whole. Match its demonstrated quality to the best-fitting band; indicative content is non-exhaustive and no single listed point guarantees a mark.
Overall response quality
Award marks holistically using the quality bands below. The indicative content identifies possible evidence and is not a point tally.
Acceptable alternatives: Accept other scientifically accurate, relevant and well-supported approaches that address the complete task.
Do not credit by itself: Do not award the top band to an unordered list that does not integrate the stimulus, biological reasoning and any required judgement.
Holistic marking bands
| Marks | Descriptor |
|---|---|
| 4 | Provides a clear, scientifically accurate and integrated response that addresses every explicit component of the task concerning vaccine antibody series; makes explicit similarities and differences across every named dimension and supports a decision or judgement where requested; and applies relevant stimulus evidence. |
| 3 | Addresses most task components with relevant biology, stimulus evidence and mostly explicit evidence-based similarities and differences, but integration or precision is uneven. |
| 2 | Provides some relevant biological information, but the response or its application to the stimulus is incomplete or mainly descriptive. |
| 1 | States one relevant biological fact or identifies one relevant feature of the stimulus. |
Section II: Written-response questions Question 30
Indicative answer: - Low filtration rate indicates reduced movement of small solutes and water from blood into nephron filtrate. - Reduced urea excretion accounts for urea accumulating in the blood. - Impaired regulation of salt and water can increase extracellular fluid volume and contribute to swelling. - Repeated measurements and clinical context are required because one abnormal value can be influenced by hydration, medicines or acute illness.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Low filtration rate indicates reduced movement of small solutes and water from blood into nephron filtrate.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Reduced urea excretion accounts for urea accumulating in the blood.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Impaired regulation of salt and water can increase extracellular fluid volume and contribute to swelling.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Repeated measurements and clinical context are required because one abnormal value can be influenced by hydration, medicines or acute illness.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 31
Indicative answer: - Two carrier parents have a one-in-four probability of an affected child for each natural conception. - IVF can produce several embryos from which cells may be sampled before transfer. - PGT can identify embryos unlikely to have the tested cystic-fibrosis genotype and reduce, but not eliminate, the chance of an affected birth. - A test result applies to the targeted variant and is not a guarantee of an embryo's overall health. - Embryo biopsy, laboratory error and possible mosaicism create residual uncertainty that should be communicated. - The couple must consider burdens such as hormone treatment, cost, success rates and decisions about embryos. - A justified decision requires informed consent, genetic counselling and respect for the couple's values rather than assuming one universally correct choice.
Question-specific marking approach
Read the response as a whole. Match its demonstrated quality to the best-fitting band; indicative content is non-exhaustive and no single listed point guarantees a mark.
Overall response quality
Award marks holistically using the quality bands below. The indicative content identifies possible evidence and is not a point tally.
Acceptable alternatives: Accept other scientifically accurate, relevant and well-supported approaches that address the complete task.
Do not credit by itself: Unsupported claims or descriptions that omit an explicit task component.
Holistic marking bands
| Marks | Descriptor |
|---|---|
| 7 | Provides a thorough, scientifically accurate evaluation using the couple's carrier status in the stimulus; links recessive inheritance risk to IVF and targeted embryo testing; weighs the likely risk reduction against test scope, residual error and treatment burdens; and supports an informed choice using relevant decision factors without assuming one universally correct option. |
| 5-6 | Provides a sound evaluation of targeted PGT for the carrier couple using relevant biology and stimulus evidence; weighs its likely benefit and important limitations and develops informed decision factors, although the risk explanation or balance of the evaluation is uneven. |
| 3-4 | Explains relevant IVF or PGT biology and some benefit, limitation or decision factor, but the evaluation is incomplete or insufficiently applied to the carrier couple. |
| 2 | Gives limited relevant information about inheritance, embryo testing or the couple's decision without developing an evaluation of IVF with PGT. |
| 1 | States one relevant fact about recessive inheritance, IVF or PGT. |
Section II: Written-response questions Question 32
Indicative answer: - Vestigial pelvic structures are homologous remnants consistent with inheritance from ancestors that had functional hind limbs. - Shared embryological patterns indicate conserved developmental pathways inherited from common ancestors. - High identity in homologous DNA sequences is consistent with relatively recent divergence. - Convergent features, limited genes or incomplete fossils can mislead, so multiple independent evidence lines and phylogenetic analysis are needed.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Vestigial pelvic structures are homologous remnants consistent with inheritance from ancestors that had functional hind limbs.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Shared embryological patterns indicate conserved developmental pathways inherited from common ancestors.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: High identity in homologous DNA sequences is consistent with relatively recent divergence.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Convergent features, limited genes or incomplete fossils can mislead, so multiple independent evidence lines and phylogenetic analysis are needed.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 33
Indicative answer: - Sensitivity is 90/100 = 90%. - There are 765 true negatives, so specificity is 765/900 = 85%. - The 135 false positives show that a positive screening result is not equivalent to a diagnosis. - A more specific confirmatory test and clinical assessment reduce inappropriate treatment and anxiety.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Sensitivity is 90/100 = 90%.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: There are 765 true negatives, so specificity is 765/900 = 85%.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The 135 false positives show that a positive screening result is not equivalent to a diagnosis.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: A more specific confirmatory test and clinical assessment reduce inappropriate treatment and anxiety.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 34
Indicative answer: - The cell has 16 chromosomes because chromosome number is counted by centromeres. - The cell has 32 chromatids because each chromosome has replicated into two sister chromatids.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The cell has 16 chromosomes because chromosome number is counted by centromeres.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The cell has 32 chromatids because each chromosome has replicated into two sister chromatids.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 35
Indicative answer: - A guide RNA directs Cas9 to a complementary target, where DNA repair after cutting can create the intended edit. - The higher yield supports performance of that edited line under the tested greenhouse conditions only. - Testing one line cannot separate the intended edit from other line-specific or tissue-culture changes. - Whole-genome or broader targeted analysis is needed because checking three predicted sites cannot exclude other off-target changes. - Independent edited lines, unedited controls, replicated trials and several salt levels would strengthen causal and performance claims. - Multi-season field trials should measure yield, plant fitness, gene flow and effects on non-target organisms under realistic conditions. - Release decisions should combine evidence with food-safety assessment, monitoring, transparent regulation and consideration of grower and community concerns.
Question-specific marking approach
Read the response as a whole. Match its demonstrated quality to the best-fitting band; indicative content is non-exhaustive and no single listed point guarantees a mark.
Overall response quality
Award marks holistically using the quality bands below. The indicative content identifies possible evidence and is not a point tally.
Acceptable alternatives: Accept other scientifically accurate, relevant and well-supported approaches that address the complete task.
Do not credit by itself: Do not award the top band to an unordered list that does not integrate the stimulus, biological reasoning and any required judgement.
Holistic marking bands
| Marks | Descriptor |
|---|---|
| 7 | Provides a thorough, scientifically accurate and coherent response that assesses the strength and limits of the single-line greenhouse evidence, off-target uncertainty and causal attribution, then supports a staged testing, regulation and monitoring decision before release; weighs evidence, benefits, limitations and uncertainty and reaches an explicit supported judgement; integrates relevant stimulus evidence; and uses precise scientific terminology. |
| 5-6 | Addresses most required task components with mostly accurate biology, relevant stimulus evidence and a supported but not fully developed evidence-based judgement, although depth, integration or the required judgement is uneven. |
| 3-4 | Addresses some task components with relevant biology and some stimulus evidence, but the explanation or integration is incomplete, and required design, judgement, comparison or decision-support elements may be weak or missing. |
| 2 | Provides limited relevant biological information, with little development or connection between ideas and no adequate completion of the central task. |
| 1 | States one relevant biological fact or identifies one relevant feature of the stimulus. |
Section II: Written-response questions Question 36
Indicative answer: - Define a case using consistent symptoms and laboratory confirmation within a specified post-event period. - Compare attack rates among attendees and non-attendees, using the same follow-up procedure for both groups. - Collect relevant confounders such as vaccination, prior infection, household exposure and time spent at the event. - Incomplete immunity and outside-exposure records can leave confounding, so an association would not by itself prove transmission at the event.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Define a case using consistent symptoms and laboratory confirmation within a specified post-event period.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Compare attack rates among attendees and non-attendees, using the same follow-up procedure for both groups.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Collect relevant confounders such as vaccination, prior infection, household exposure and time spent at the event.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Incomplete immunity and outside-exposure records can leave confounding, so an association would not by itself prove transmission at the event.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 37
Indicative answer: - The heterozygous parent has genotype Pp and produces P and p gametes. - The white parent has genotype pp and produces only p gametes. - The expected Pp:pp ratio is 1:1, which is close to 82:78 after random sampling.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The heterozygous parent has genotype Pp and produces P and p gametes.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The white parent has genotype pp and produces only p gametes.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The expected Pp:pp ratio is 1:1, which is close to 82:78 after random sampling.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 38
Indicative answer: - The child's 120 and 260 base-pair bands can be inherited from the mother. - The unexplained 180 and 310 base-pair bands are both present in candidate X. - Candidate Y lacks both unexplained child bands, so X is consistent with the tested loci whereas Y is excluded. - Consistency at these loci is not proof of parentage; more independent loci and appropriate controls are required.
Detailed marking criteria
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The child's 120 and 260 base-pair bands can be inherited from the mother.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: The unexplained 180 and 310 base-pair bands are both present in candidate X.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Candidate Y lacks both unexplained child bands, so X is consistent with the tested loci whereas Y is excluded.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Integrated response (1 mark)
Awards one mark for accurately establishing this question-specific point: Consistency at these loci is not proof of parentage; more independent loci and appropriate controls are required.
Acceptable alternatives: Accept scientifically accurate equivalent wording that is applied to the supplied context.
Do not credit by itself: States a general fact without applying it to the named evidence, variable or biological mechanism.
Section II: Written-response questions Question 39
Indicative answer: - Measles spreads through respiratory particles and is highly transmissible, so susceptible clusters can sustain rapid outbreaks. - Two-dose vaccination induces antigen-specific adaptive immunity and memory, reducing susceptibility and transmission. - Offer accessible vaccination through schools, mobile clinics and extended hours rather than relying only on central appointments. - Use trusted local health workers to address specific concerns transparently and obtain informed consent. - Rapid case recognition, laboratory confirmation, isolation while infectious and contact follow-up can interrupt current chains. - Coverage and case data should be monitored by location and age to direct resources without stigmatising communities. - The combined plan is stronger than one measure because it reduces susceptibility, shortens transmission chains and addresses practical causes of low uptake.
Question-specific marking approach
Read the response as a whole. Match its demonstrated quality to the best-fitting band; indicative content is non-exhaustive and no single listed point guarantees a mark.
Overall response quality
Award marks holistically using the quality bands below. The indicative content identifies possible evidence and is not a point tally.
Acceptable alternatives: Accept other scientifically accurate, relevant and well-supported approaches that address the complete task.
Do not credit by itself: Do not award the top band to an unordered list that does not integrate the stimulus, biological reasoning and any required judgement.
Holistic marking bands
| Marks | Descriptor |
|---|---|
| 7 | Provides a thorough, scientifically accurate and coherent response that links susceptible clusters and measles transmission to prioritised vaccination, accessible delivery, surveillance, outbreak response and measurable coverage and disease outcomes; aligns controls with biological mechanisms, prioritises feasible implementation, includes surveillance and explicit evaluation criteria, and addresses uncertainty, access, equity and relevant ethics; integrates relevant stimulus evidence; and uses precise scientific terminology. |
| 5-6 | Addresses most required task components with mostly accurate biology, relevant stimulus evidence and a generally workable mechanism-based intervention and monitoring rationale, although depth, integration or the required judgement is uneven. |
| 3-4 | Addresses some task components with relevant biology and some stimulus evidence, but the explanation or integration is incomplete, and required design, judgement, comparison or decision-support elements may be weak or missing. |
| 2 | Provides limited relevant biological information, with little development or connection between ideas and no adequate completion of the central task. |
| 1 | States one relevant biological fact or identifies one relevant feature of the stimulus. |
Section II: Written-response questions Question 40
Indicative answer: - Type 2 diabetes involves impaired insulin action and, over time, inadequate beta-cell compensation, causing chronic high blood glucose. - Affordable healthy-food access and safe opportunities for physical activity address modifiable risks at a population level. - Culturally appropriate screening can identify elevated risk or disease earlier, but results require confirmatory assessment. - Individual management may combine dietary change, physical activity, glucose monitoring and prescribed medicines according to clinical need. - Regular review should monitor glucose control, cardiovascular risk, kidney function, eyes and feet to reduce complications. - Program evaluation should track participation, incidence, clinical outcomes and equity, not merely the number of education sessions delivered. - The strongest approach combines structural prevention with accessible long-term care because education alone cannot overcome cost, environment or service barriers.
Question-specific marking approach
Read the response as a whole. Match its demonstrated quality to the best-fitting band; indicative content is non-exhaustive and no single listed point guarantees a mark.
Overall response quality
Award marks holistically using the quality bands below. The indicative content identifies possible evidence and is not a point tally.
Acceptable alternatives: Accept other scientifically accurate, relevant and well-supported approaches that address the complete task.
Do not credit by itself: Do not award the top band to an unordered list that does not integrate the stimulus, biological reasoning and any required judgement.
Holistic marking bands
| Marks | Descriptor |
|---|---|
| 7 | Provides a thorough, scientifically accurate and coherent response that integrates type 2 diabetes biology with feasible prevention, accessible clinical management, complication monitoring, equity and explicit long-term program evaluation; aligns controls with biological mechanisms, prioritises feasible implementation, includes surveillance and explicit evaluation criteria, and addresses uncertainty, access, equity and relevant ethics; integrates relevant stimulus evidence; and uses precise scientific terminology. |
| 5-6 | Addresses most required task components with mostly accurate biology, relevant stimulus evidence and a generally workable mechanism-based intervention and monitoring rationale, although depth, integration or the required judgement is uneven. |
| 3-4 | Addresses some task components with relevant biology and some stimulus evidence, but the explanation or integration is incomplete, and required design, judgement, comparison or decision-support elements may be weak or missing. |
| 2 | Provides limited relevant biological information, with little development or connection between ideas and no adequate completion of the central task. |
| 1 | States one relevant biological fact or identifies one relevant feature of the stimulus. |
Diagnostic Checklist
| Review focus | Section | Reflection and next action |
|---|---|---|
| Module 5 - Heredity | 3, 8, 11, 14, 17, 23, 28, 31, 34, 37 | Revise reproduction, cell replication, DNA and polypeptide synthesis, inheritance patterns and evidence-based genetic technologies. |
| Module 6 - Genetic Change | 1, 5, 12, 15, 18, 21, 25, 32, 35, 38 | Practise explaining mutation, biotechnology, population change, evolutionary mechanisms and the limits of genetic evidence. |
| Module 7 - Infectious Disease | 2, 6, 9, 16, 19, 22, 26, 29, 36, 39 | Connect pathogen biology, transmission, immune responses, epidemiological evidence and disease-control mechanisms. |
| Module 8 - Non-infectious Disease and Disorders | 4, 7, 10, 13, 20, 24, 27, 30, 33, 40 | Link homeostatic disruption, non-infectious disease causes, epidemiology, diagnosis, treatment and prevention to supplied evidence. |