Identify variables and control
An enzyme investigation in a conservation evidence lesson changes pH and measures reaction rate, but temperature varies between trials. Identify the validity issue. Use the labelled diagram, data, or experimental evidence before writing the answer. Enter the answer and choose the interpretation that best matches the HL Biology evidence.
Worked practice: biological evidence and answer
Use the labelled biological evidence first, then connect it to the final answer.
Write a full answer
Now write the response in full, in your own words — this is what the exam asks for. The AI marks it on the same moves you built above (focus, evidence, technique, judgement) and gives feedback on reasoning, evidence, and expression.