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Figure 13 shows the heart rate of person A and person B - Edexcel - GCSE Biology - Question 8 - 2020 - Paper 1
Question 8
Figure 13 shows the heart rate of person A and person B. Person A does not do any regular exercise. Person B has been running regularly for one year. Both people ... show full transcript
Worked Solution & Example Answer:Figure 13 shows the heart rate of person A and person B - Edexcel - GCSE Biology - Question 8 - 2020 - Paper 1
Step 1
Compare the heart rates of person A with the heart rates of person B.
Answer
The heart rate of person A is generally higher than that of person B. During exercise, person A's heart rate increases more significantly compared to person B's relatively stable heart rate. This indicates that person A's cardiovascular system is reacting more dramatically to the exertion because he is not accustomed to regular exercise, while person B maintains a more controlled elevation in heart rate due to regular training.
Step 2
Calculate the cardiac output for person B before exercising.
Answer
Cardiac output (CO) can be calculated using the formula:
Given that the stroke volume for person B is 61 ml per beat, we need the heart rate before exercising. Assuming a resting heart rate of approximately 70 bpm, we calculate:
Step 3
Explain why the heart rate for person A needed to be higher than the heart rate for person B during exercise.
Answer
Person A's higher heart rate is necessary because his untrained body requires a more significant increase in blood flow to meet the oxygen and nutrient demands during exercise. In contrast, person B's body is more efficient due to regular training, allowing for sufficient oxygen delivery with a lower heart rate. This reflects the adaptation of person B's cardiovascular system to regular exercise, requiring less effort to achieve the same levels of output.