AQAGCSEBiologyFoundation2 marks
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.
Calculate the percentage increase in reaction rate if the rate at 20 °C is 30 units min⁻¹ and at 30 °C is 45 units min⁻¹.
Show answer, mark scheme and Mentor explanation
Answer and mark-scheme guidance
MP1: Increase = 45 − 30 = 15 units min⁻¹
MP2: Percentage increase = (15 ÷ 30) × 100 = 50%
Mentor — AI Tutor
Can you spot the two calculation steps the mark scheme needs?
This question is testing whether you can calculate a percentage increase in reaction rate from two values. The mark scheme gives 1 mark for finding the increase first: 45 − 30 = 15 units min⁻¹. It then gives 1 mark for using that increase with the original 20 °C rate: (15 ÷ 30) × 100 = 50%. To secure both marks, your working needs those two stages.
Quick takeaway: First find the increase, then divide by the original value and multiply by 100.