The diagram shows capillaries carrying blood through muscle - Edexcel - GCSE Biology - Question 2 - 2017 - Paper 1
Question 2
The diagram shows capillaries carrying blood through muscle.
(a) Complete the sentence by putting a cross (X) in the box next to your answer.
The blood vessel that... show full transcript
Worked Solution & Example Answer:The diagram shows capillaries carrying blood through muscle - Edexcel - GCSE Biology - Question 2 - 2017 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The correct answer is C: pulmonary vein. This vessel carries oxygenated blood back to the heart after it has circulated through the body.
Step 2
Explain how the concentration gradient is maintained between the blood and muscles.
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Answer
The concentration gradient is maintained by the continuous supply of oxygen and removal of carbon dioxide. Oxygen from the bloodstream diffuses into the muscle cells where it is utilized for cellular respiration. Simultaneously, carbon dioxide produced as a waste product diffuses from the muscle cells back into the blood, thereby lowering its concentration in the muscles compared to the blood, which sustains the gradient.
Step 3
Complete the word equation for aerobic respiration.
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Answer
GLUCOSE + (oxygen) → carbon dioxide + WATER
Step 4
Describe the relationship between cardiac output and running speed.
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Answer
As running speed increases, cardiac output increases. This relationship is linear up to speeds of approximately 12 to 16 km per hour, after which the increase in cardiac output becomes less pronounced.
Step 5
Explain why this runner gets muscle cramp when he runs at speeds over 24 km per hour.
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Answer
At higher speeds, the demand for oxygen in the muscles often exceeds supply, leading to anaerobic respiration. This can cause a buildup of lactic acid, resulting in muscle fatigue and cramps.
