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

WACE Biology is on Monday 9 November at 2 pm, WA time.

Last year's mean was 61.97%. The extended-answer means were below 50% for both units, despite much stronger multiple-choice results. Knowing the term and explaining the process are different skills.

I've checked the 2025 examiner report and marking key. Here are four revision targets.

1. Question 22: Validity is not just repeating the experiment

Where students went wrong: Many candidates did not identify how experimental validity could be improved.

What they should have done: Identify what prevents the method from testing the intended relationship.

My revision check: ask which other variable could explain the result. Control that variable or redesign the comparison. Repeating a flawed method can produce consistent results without removing the flaw. Practise distinguishing a validity improvement from a reliability improvement and explain why your change helps.

2. Question 27: Populations evolve

Where students went wrong: Candidates confused genetic change in populations with change in an individual.

What they should have done: Explain natural selection through differential survival and reproduction, leading to changes in allele frequencies across generations.

My practice check: look for phrases suggesting an individual developed a useful inherited trait because it needed one. Replace that shortcut with the sequence: heritable variation, selection pressure, reproductive differences and population change. Keep the timescale and level of explanation clear.

3. Question 35(a)(ii): Answer the structural comparison

Where an answer loses marks: The marking key required a structural similarity and difference between mRNA and tRNA. A description of their jobs did not answer that requirement.

What you needed: For example, both contain RNA nucleotides; mRNA carries codons while tRNA has an anticodon. Make the comparison explicit.

My revision drill: put “structure” and “function” in separate columns. Sort your facts before writing, then select only those that answer the command. This prevents a correct fact from becoming an irrelevant answer.

4. Question 36: Break the extended answer into its required parts

Where an answer loses marks: Part (a) required replication steps plus explanations of complementary pairing and hydrogen bonds. Part (b) required the roles of geographic isolation, selection and mutation in allopatric speciation.

What you needed: Cover every requested component and link the mechanism to its consequence. Isolation blocks gene flow; mutation supplies new alleles; differing selection pressures can drive divergence.

My planning routine: convert the question's clauses into headings before writing. Under each, write a short chain of causes and effects. Then check whether you have explained the links instead of simply listing terminology.

Sources: 2025 examiner report and 2025 marking key. The revision drills are my suggestions.

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