Control of blood water potentialAQA A-Level Biology: Mind map

Exam questions on Control of blood water potential

1. A marathon runner sweats heavily during a race in hot weather and drinks nothing for two hours. Her blood water potential falls, and her body responds by changing the volume and concentration of her urine.
   Explain how the release of ADH changes the volume and concentration of the runner's urine.2 marks
2. A physiologist is studying filtration in the kidney of a mammal. In each nephron, blood flows from an afferent arteriole into a knot of capillaries called the glomerulus, and leaves in an efferent arteriole. Fluid is forced out of the capillaries into the lumen of the Bowman's capsule.
   Describe how glucose in the filtrate is reabsorbed into the blood in the proximal convoluted tubule.2 marks
3. The kangaroo rat lives in deserts and produces urine far more concentrated than that of a beaver, which lives by rivers. Anatomical studies show that the kangaroo rat has nephrons with much longer loops of Henle than the beaver, which has nephrons with short loops.
   Describe how the loop of Henle maintains a gradient of sodium ions in the tissue fluid of the medulla.3 marks