AQA GCSE Biology Foundation • Unit 11 key Ideas • Key Idea 4

Can you secure both marks on this AQA GCSE Biology enzyme question? with AI Marker.

Use this AQA GCSE Biology revision page to see exactly what this Foundation question is testing in Unit 11 key Ideas, Key Idea 4. It focuses on GCSE Biology exam practice around variables in an enzyme experiment and how the mark scheme rewards a clear explanation. AI Marker gives you structured GCSE revision questions with instant AI marking, plus Mentor — an AI Tutor built for GCSE revision — across 75,000+ GCSE questions.

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AQA • Biology • Unit 11 key Ideas

Explain why it is important to keep enzyme concentration constant during the experiment.

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GCSE revision question
Question context

A student is planning an experiment to investigate the effect of temperature on enzyme activity. They plan to measure the rate of reaction at different temperatures, keeping the enzyme concentration constant. They consider variables, controls, risks, and accuracy in their experimental design.

Explain why it is important to keep enzyme concentration constant during the experiment.

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Answer and mark-scheme guidance

MP1: Changing enzyme concentration would affect the reaction rate independently of temperature
MP2: This would make it difficult to determine the effect of temperature alone

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Can you spot the two separate mark-scheme points in this enzyme experiment question?

To earn both marks, your answer needs two linked ideas. First, changing the enzyme concentration would change the reaction rate as well. Second, that would mean you could not tell the effect of temperature by itself. The key is to show that enzyme concentration must stay constant so temperature is the only factor affecting the result.

Quick takeaway: Two marks come from stating that enzyme concentration affects reaction rate and that changing it would stop you isolating the effect of temperature alone.

GCSE Biology revision: what this mark scheme is really checking

This is a focused piece of GCSE Biology revision on experimental control in an enzyme activity investigation. In this AQA GCSE Biology question, the mark scheme is checking whether you understand why a control variable matters: if enzyme concentration changes, the reaction rate changes independently of temperature, so the effect of temperature alone cannot be determined. That is the whole target of the answer. For GCSE Biology questions and answers, GCSE exam practice and GCSE mark scheme guidance, AI Marker helps你

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