Excretion and the kidneyIB MYP Biology: Mind map

Exam questions on Excretion and the kidney

1. A runner completes a marathon in Nairobi on a hot day. Afterwards she is breathing deeply, her skin is wet with sweat, and she passes only a small volume of dark yellow urine.
   Explain why the runner passes only a small volume of dark yellow urine.2 marks
2. A patient in Lagos has a kidney infection. A urine test finds protein in her urine, which is not normally present in healthy urine. Her doctor says that her kidneys are not working as well as they should.
   Explain why protein is not normally found in urine, and why it appears in urine when the kidneys are damaged.2 marks
3. A sports scientist investigates whether exercising in hot conditions changes how much urine a person produces. Four volunteers each do two hours of gentle exercise in a room at 20 °C, and on another day in a room at 35 °C. Each volunteer drinks 500 mL of water at the start. The mean volume of urine collected over the two hours is 310 mL at 20 °C and 140 mL at 35 °C.
   State the trend in the results and calculate the percentage decrease in mean urine volume at 35 °C compared with 20 °C. Give your answer to the nearest whole number.3 marks