Two female athletes, Chloe and Denise, investigate how the resistance level of a stationary exercise bike affects their heart rate. They each record their heart rate at rest. Chloe exercises for 5 minutes at a low resistance level. Denise exercises for 5 minutes at a high resistance level. Both athletes measure their heart rate each minute during the 5 minutes of exercise. Their results are shown in the table: | Time (min) | Chloe's Heart rate (bpm) | Denise's Heart rate (bpm) | | :---: | :---: | :---: | | 0 (rest) | 64 | 66 | | 1 | 80 | 95 | | 2 | 94 | 118 | | 3 | 105 | 131 | | 4 | 112 | 140 | | 5 | 116 | 145 |
What is the dependent variable in this investigation?
Identify two variables that the athletes controlled in this experiment.
Why is it important to record the athletes' heart rate at rest before they begin exercising?
Use the results in the table to calculate the percentage difference in heart rate increase between Chloe and Denise. Use the formula:
Percentage difference=increase in Denise−increase in Chloeincrease in Chloe×100 \text{Percentage difference} = \frac{\text{increase in Denise} - \text{increase in Chloe}}{\text{increase in Chloe}} \times 100 Percentage difference=increase in Chloeincrease in Denise−increase in Chloe×100Give your answer to 1 decimal place.
44 exam-style questions on OCR GCSE Biology Practical skills. Each one has a worked solution and a mark scheme showing where the marks go.