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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 (✗) 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
Step 2
Explain how the concentration gradient is maintained between the blood and muscles.
Answer
The concentration gradient is maintained by the continuous supply of oxygen in the blood, which moves from areas of higher concentration (in the blood) to areas of lower concentration (in the muscle tissues).
As oxygen is used by the muscle cells for aerobic respiration, it keeps the concentration in the muscles lower compared to that in the blood, promoting the diffusion of more oxygen from the blood into the muscles.
Step 3
Step 4
Describe the relationship between cardiac output and running speed.
Answer
As running speed increases, cardiac output also increases. Initially, there is a linear increase in cardiac output up to around 12 to 16 km per hour. Beyond this speed, the increase in cardiac output slows down, indicating that the heart is reaching its maximum efficiency.
Step 5
Explain why this runner gets muscle cramp when he runs at speeds over 24 km per hour.
Answer
At speeds over 24 km per hour, the runner's muscles may not receive sufficient oxygen due to the high demand for energy, leading to anaerobic respiration. This results in the buildup of lactic acid, causing muscle fatigue and cramping.