2026 WACE Human Biology exam: What to learn from last year's mistakes

Exam: Thursday 5 November 2026, 9.20 am. Western Australia local time.

2025 exam average: 64.82%. Multiple choice averaged 78.32%, short answer 62.80%, Unit 3 extended answer 56.73% and Unit 4 extended answer 42.53%.

I've gone through last year's report and marking key. Unit 4 extended responses were the weakest section. The report specifically flags Q35 on biotechnology and Q36 on protein evidence: knowing the technique's name wasn't enough.

1. Q35(a): Gene flow isn't genetic drift

2 marks.

Where an answer loses marks

Naming a random change in allele frequency when the question asks how a mutation moves between populations.

What you needed

Identify gene flow and explain transfer through migration. Link movement of individuals to movement of genetic material into another population.

As a revision check, make two separate examples: one involving migration and breeding, another involving chance changes in a small population. If your explanation fits both without changing anything, it needs more precision.

2. Q35(c): Explain what the bands tell you

6 marks.

Where students went wrong

The report identifies difficulty applying PCR and gel electrophoresis to the question.

What they should have done

Connect the methods to evidence for different lactose-tolerance mutations. The key includes collecting DNA from different populations, using the same restriction enzyme, PCR amplification, size separation, comparing bands and linking different patterns to different mutations.

Don't spend the whole answer describing temperatures in a PCR cycle. Finish with the comparison and what it would support. The question is asking you to use the technique to investigate a claim.

3. Q36(d): Protein similarities need an evolutionary explanation

4 marks.

Where students went wrong

The examiner report flags weak explanations of protein analysis as evidence.

What they should have done

Compare amino-acid sequences, link differences to changes in the DNA coding for them, and explain why greater similarity supports a more recent common ancestor.

Build the answer as a chain: what is compared → why it can differ → what the comparison suggests. “Their proteins are similar” gives a result but leaves the inference unexplained.

4. Q40(a): A founder effect isn't automatically speciation

8 marks.

Where an answer loses marks

Jumping from an isolated island population to a claim that a new species has formed.

What you needed

The question asks why migrant-founded populations could differ genetically from the original population. Explain how a small founding group may carry an unrepresentative sample of the original alleles. Then follow the consequences for allele frequencies.

This is a mechanism question. Plan the steps before writing and apply each one to the island context. The report explicitly warns against confusing founder effect with speciation.

Marks above are allocations, not question averages. Work through the 2025 official paper, marking key and examiner report. Check the official timetable.

Sorry guys, shameless plug, I gotta do this. I'm the founder of ATARMAXXING, so take a look at the WACE Human Biology practice exams with worked solutions if you want more practice. You can preview the Human Biology pack before buying. Try an unfamiliar scenario and mark your explanation, not just your recall.

Discuss this WACE Human Biology exam breakdown on the subject board.