Heart Rate and Adrenaline

IGCSE Edexcel Biology
2.66 Heart Rate Changes
Key Concept: Heart rate increases during exercise and under the influence of adrenaline to supply more oxygen.

Section A: Exercise

1. Describe how heart rate changes during exercise. [3]

Section B: Hormones

2. State the effect of adrenaline on heart rate. [2]

Section C: Application

3. Explain why a faster heart rate helps active muscles. [2]
4. A student has a resting heart rate of 70 bpm and an exercise heart rate of 140 bpm. Calculate the percentage increase. [2]
Total marks: 9

Mark Scheme

1. Heart rate increases to supply more oxygen and remove $CO_2$; returns to normal after exercise (any three points) [3]
2. Adrenaline increases heart rate and force of contraction [2]
3. Delivers more oxygen and glucose for respiration and removes wastes faster [2]
4. Increase = 70; percentage increase $= 70/70 \times 100 = 100\%$ [2]