Fig. 1 shows a student using a colour chart to compare the urine of a runner before and after a 10 km race on a hot day. The runner lost water in sweat. The...
Question 1 Report
Fig. 1 shows a student using a colour chart to compare the urine of a runner before and after a 10 km race on a hot day. The runner lost water in sweat. The body must keep the water concentration of the blood within a narrow range so that body cells work properly.
(a) Identify the organ that filters the runner's blood to make urine. [1]
(b) Explain why the urine sample collected after the race is likely to be darker than the sample collected before the race. [2]
(c) Use ideas about hormones to explain how the body reduces further water loss in urine after sweating. [3]
(d) Give one sensible action the runner could take to restore the water balance of the blood. [1]
Answer Details
(a) Kidney [1] (b) More water has been lost in sweat / less water is available for urine [1]; the urine therefore contains a higher concentration of dissolved waste / is more concentrated [1] (c) Water concentration of blood falls / blood becomes too concentrated [1]; pituitary releases more ADH [1]; kidneys reabsorb more water into the blood / produce a smaller volume of concentrated urine [1] (d) Drink water / drink a suitable rehydration drink [1]
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