Figure 1 shows a human heart - AQA - GCSE Biology Combined Science - Question 1 - 2019 - Paper 1
Question 1
Figure 1 shows a human heart.
1. Which blood vessel carries deoxygenated blood away from the heart to the lungs?
Tick (✓) one box.
A
B
C
D
2. The natural resting h... show full transcript
Worked Solution & Example Answer:Figure 1 shows a human heart - AQA - GCSE Biology Combined Science - Question 1 - 2019 - Paper 1
Step 1
Which blood vessel carries deoxygenated blood away from the heart to the lungs?
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Answer
B
Step 2
Where in the heart are 'pacemaker cells' found?
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Answer
Right atrium
Step 3
Where does the drug digitalis originate from?
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Answer
Foxgloves
Step 4
Calculate stroke volume X in Table 1.
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Answer
To find stroke volume X, we will use the equation for cardiac output:
extcardiacoutput=extstrokevolumeimesextheartrate
From Table 1, while taking beta blockers during exercise:
Cardiac output = 2800 cm³/min
Heart rate = 52 beats/min
Thus, we can rearrange the equation to solve for stroke volume:
Explain why beta blockers can have this effect during exercise.
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Answer
Beta blockers work by reducing the heart rate and decreasing the force of contraction of the heart muscle. This leads to an overall reduction in cardiac output. During exercise, the body usually requires increased blood flow to supply more oxygen to the muscles. However, with beta blockers inhibiting this increase, oxygen delivery becomes limited, causing individuals to feel out of breath. Moreover, beta blockers can decrease stroke volume, which further diminishes the adequacy of oxygen supply during physical activity. This can result in exertional dyspnea (difficulty breathing) as the body's demands are not met.
