17 (a) Fig. 17.1 shows a section through a human heart.
(i) On Fig. 17.1 draw an arrow to identify one valve. Label the arrow V.
(ii) On Fig. 17.1 draw a second ar... show full transcript
Worked Solution & Example Answer:17 (a) Fig - OCR Gateway - GCSE Biology - Question 17 - 2022 - Paper 1
Step 1
Draw an arrow to identify one valve. Label the arrow V.
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Answer
The valve can be identified as the tricuspid valve. Drawing an arrow pointing towards it and labeling it V is required.
Step 2
Draw a second arrow to identify one atrium. Label this arrow A.
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Answer
The right atrium should be identified. An arrow should be drawn towards the right atrium and labeled as A.
Step 3
Explain why the left ventricle has more muscle than the right ventricle.
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Answer
The left ventricle has more muscle because it needs to pump blood to the entire body, requiring greater force and pressure compared to the right ventricle, which only pumps blood to the lungs.
Step 4
Calculate how many times blood will circulate around the body in one hour.
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Answer
If the heart circulates blood three times every minute, then in one hour (60 minutes), it will circulate blood a total of:
3 times/minute×60 minutes=180 times
Step 5
Write down one conclusion the scientist can make from the data.
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Answer
One conclusion could be that as the time spent exercising increases, the resting heart rate tends to decrease.
Step 6
Identify the mistake the student has made.
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Answer
The mistake is that veins carry blood towards the heart, but they actually have valves that prevent backflow. The description needs to specify that they carry deoxygenated blood (except the pulmonary veins).
Step 7
Explain why the human circulatory system is described as a double circulatory system.
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Answer
The human circulatory system is described as a double circulatory system because it consists of two separate circuits: the pulmonary circuit, which carries deoxygenated blood from the heart to the lungs, and the systemic circuit, which carries oxygenated blood from the heart to the rest of the body.
