Mark it yourself: VCE Biology Section B short and extended answers

How to use this pack

Section B of the VCE Biology exam is where most marks are won and lost. VCAA does not publish a mark-by-mark scheme, but each year's examination report shows the average mark for every question, what answers could have included, high-scoring student responses, and the errors that cost marks. This pack uses the 2025 VCE Biology external assessment report to show how four common question types are marked. For each type you get an original practice question with our own high-scoring sample answer (written by ExamExplained, not an official VCAA response), the errors to avoid and a self-marking prompt.

How VCE Biology answers are assessed

• Marks match points. The number of marks tells you how many distinct, accurate points are needed. The 2025 report advised students to "use the number of marks as an indication of the level of detail required".
• Command terms matter. The VCAA glossary defines contrast as "Show how things are different or opposite", explain as "Give a detailed account of why and/or how with reference to causes, effects, continuity, change, reasons or mechanisms", and justify as "Show, prove or defend, with reasoning and evidence".
• Context is rewarded, generic answers are not. The report noted "pre-planned, generic responses" about booster vaccines that did not refer to the mother or baby in the question, and encouraged students "to relate their answers to the context of the question".
• Dot points are fine. The report states that "Answering in dot points is acceptable and can help students to ensure they are addressing all parts of a question."

The mark breakdowns below are our interpretation of the report's answer lists and the marks available, not an official VCAA scheme.

Type 1: the "contrast" question (3 to 4 marks)

What the report says. In 2025, Question 5b (4 marks) asked students to contrast the adaptive immune response to an extracellular and an intracellular pathogen. The report listed four contrasts (type of immunity, cells involved, mechanisms, memory cells) and commented that some students "included similarities between the two responses" and that "'contrast' requires a student to outline differences, not similarities."

Practice question (ours). Contrast the light-dependent and light-independent stages of photosynthesis in a C3 plant. (4 marks)

Our sample answer (full marks).

• Location: the light-dependent stage occurs on the thylakoid membranes of the chloroplast, whereas the light-independent stage (Calvin cycle) occurs in the stroma.
• Inputs: the light-dependent stage uses light energy, water, NADP and ADP + Pi, whereas the light-independent stage uses carbon dioxide, NADPH and ATP.
• Outputs: the light-dependent stage produces oxygen, NADPH and ATP, whereas the light-independent stage produces glucose and returns NADP and ADP + Pi.
• Enzyme: the light-independent stage depends on Rubisco to fix carbon dioxide, whereas the light-dependent stage does not use Rubisco.

Why it earns 4: each point names the SAME feature for both stages, and the word "whereas" forces a contrast.

Type 2: explaining a trend in data (4 to 5 marks)

What the report says. In 2025, Question 2b (5 marks) asked students to explain the pattern in a graph about the trp operon. The report said students "were required to make reference to both timeframes referred to in the question", that "accurate knowledge of these regulation mechanisms is required for the responses to be awarded full marks", and reminded students "to read the axis labels carefully", because many "confused the y-axis as representing trp concentration as opposed to enzyme activity".

Practice question (ours). The rate of oxygen production by an aquatic plant was measured at different temperatures, with light intensity and CO₂ concentration kept constant.

Explain the trend in the data between 10 °C and 50 °C. (4 marks)

Our sample answer (full marks).

• From 10 °C to 30 °C the rate of oxygen production increased from 8 to 25 mL per hour. As temperature rises, enzymes of photosynthesis (such as Rubisco) and their substrates have more kinetic energy, so they collide more often and with more energy, increasing the rate of reaction.
• The rate was highest at about 30 °C, close to the optimum temperature for these enzymes.
• Above 30 °C the rate fell sharply, to 12 mL per hour at 40 °C. High temperatures disrupt the hydrogen bonds that maintain the enzymes' tertiary structure, changing the shape of the active site so substrates can no longer bind: the enzymes denature.
• At 50 °C no oxygen was produced, suggesting the enzymes needed for photosynthesis were fully denatured.

Other common errors: explaining the rise without the fall (or the reverse); describing the trend with no mechanism; reading a rate axis as a concentration axis.

Type 3: applying an idea to a new context (3 marks)

What the report says. In 2025, Question 7b (3 marks) asked students to identify the process responsible for DNA differences in introduced honey bees and explain how it helped the colonies expand. The report noted that many responses did not "identify the process" at all, and that "natural selection or genetic drift were common incorrect answers", because these "change the frequency of alleles rather than actually producing the DNA differences". For Question 7c the report warned against "Lamarckian statements, such as suggesting the native bees adapted in order to survive" and encouraged students to "relate their answers to the context of the question, rather than simply regurgitating pre-planned responses".

Practice question (ours). An island population of mosquitoes was sprayed with an insecticide every year for 10 years. At the start, 1% of mosquitoes were resistant to the insecticide; after 10 years, 80% were resistant. Explain how this change occurred. (3 marks)

Our sample answer (full marks).

• Before spraying began, a small number of mosquitoes (about 1%) already carried an allele for insecticide resistance, which had arisen by random mutation.
• The insecticide acted as a selection pressure: resistant mosquitoes were more likely to survive the spraying and reproduce, while susceptible mosquitoes were killed.
• The resistant mosquitoes passed the resistance allele to their offspring, so over many generations of spraying its frequency in the island's gene pool increased, until 80% of the population was resistant.

Type 4: bioethics (2 to 3 marks)

What the report says. In 2025, Question 8f (2 marks) asked students to agree with one of two students' ethical positions on an experiment. The report explained that high-scoring answers defined the ethical concept and applied it to details from the article, noted that "Some responses included justifications that did not match the student (X or Y) they were agreeing with", and said students "need to be able to demonstrate and apply ethical understanding using the ethical concepts outlined" in the study design.

The study design lists these ethical concepts: integrity, justice, beneficence ("the commitment to maximising benefits and minimising the risks and harms"), non-maleficence (avoiding harm, and ensuring any harm is "not disproportionate to the benefits") and respect.

Practice question (ours). Scientists propose releasing genetically modified mosquitoes carrying a gene drive that would greatly reduce the population of a malaria-carrying mosquito species in one region. Using one ethical concept, justify whether the release should go ahead. (2 marks)

Our sample answer (full marks, one of several acceptable positions).

The release should go ahead, based on beneficence, which means maximising benefits while minimising risks and harms. Reducing the mosquito population could prevent many malaria infections and deaths in the region, a very large benefit, and the risk can be reduced by trialling the release in a contained area and monitoring the ecosystem before a wider release.

An equally valid answer could argue against the release using non-maleficence, pointing out that the ecological harm of removing a species from food webs is uncertain and may be irreversible, so it may be disproportionate. What matters is that the concept, its definition and the scenario details all support the same position.

Your self-marking prompt

Paste this into ChatGPT or another AI tool, with the question and your answer. Add the relevant "what the report says" notes from above, or, for a past exam, the matching section of that year's examination report.

You are an experienced VCE Biology assessor. Mark my answer to this
Section B question using the VCAA examination report notes below. VCAA
does not publish a mark scheme, so award one mark only for each distinct,
accurate, relevant point, up to the marks available.

Question ([number] marks): [paste the question and any data]

Examination report notes / acceptable points:
[paste what the report says answers could include, or the notes above]

My answer:
[paste your answer]

1. List each point in my answer and say whether it earns a mark, and why.
2. Flag any inaccurate biology, any similarities in a "contrast" answer,
   any Lamarckian wording, and anywhere I ignored the question's context
   or data.
3. Give my mark out of [number].
4. Tell me exactly what one extra point would have earned the next mark.
   Do not rewrite my answer.

Next steps

• Practise Section A with the harder exam-style VCE Biology quiz.
• Revise the content behind these question types in the Unit 3 deep dive and the Unit 4 deep dive.
• Then complete a full VCAA past examination and mark it against that year's examination report.