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Figure 5 shows the estimated blood flow through some parts of the body when a person is at rest and during exercise - Edexcel - GCSE Biology Combined Science - Question 3 - 2018 - Paper 1
Question 3
Figure 5 shows the estimated blood flow through some parts of the body when a person is at rest and during exercise. | part of the body | estimated r... show full transcript
Worked Solution & Example Answer:Figure 5 shows the estimated blood flow through some parts of the body when a person is at rest and during exercise - Edexcel - GCSE Biology Combined Science - Question 3 - 2018 - Paper 1
Step 1
Compare the rate of blood flow through the body when this person is at rest and during exercise.
Answer
The blood flow through the brain and other organs remains largely unchanged during exercise, indicating that these areas maintain their blood supply to preserve function. However, blood flow to the heart muscle increases significantly during exercise, rising from 350 cm³/min to 1,150 cm³/min, ensuring that the heart receives adequate oxygen and nutrients for heightened activity. Conversely, the digestive system experiences a reduction in blood flow, decreasing from 2500 cm³/min at rest to 1200 cm³/min during exercise, reflecting the prioritization of blood supply to more active muscles.
Step 2
Step 3
Calculate the heart rate.
Answer
To calculate the heart rate (in beats per minute), we use the formula:
ext{Heart Rate} = rac{ ext{Cardiac Output}}{ ext{Stroke Volume}}Substituting the values:
ext{Heart Rate} = rac{4.9 ext{ L/min}}{70 ext{ mL/beat}} = rac{4900 ext{ mL/min}}{70 ext{ mL/beat}} = 70 ext{ beats/min}Thus, the heart rate is 70 beats per minute.