The kidney and osmoregulationEdexcel A-Level Biology B: Mind map

Exam questions on The kidney and osmoregulation

1. In a hospital laboratory, samples of blood plasma, glomerular filtrate and urine from a healthy adult are compared. The plasma contains water, glucose, amino acids, urea, mineral ions and large proteins such as albumin. The filtrate is collected from the Bowman's capsule.
   Explain why red blood cells and albumin are found in the plasma but not in the glomerular filtrate.2 marks
2. A scientist follows the glucose concentration along the nephron of a healthy person after a meal. The filtrate entering the proximal convoluted tubule has the same glucose concentration as plasma, but none is detectable by the end of the tubule. The cells lining the tubule have microvilli and many mitochondria.
   A person with untreated diabetes mellitus has glucose in their urine, although their kidneys are healthy. Explain why.2 marks
3. A researcher compares the kidneys of a beaver, which lives in water, with those of a kangaroo rat (Dipodomys sp.), which lives in desert and rarely drinks. The beaver has short loops of Henle. The kangaroo rat has very long loops of Henle for its body size and a thick medulla, and it produces very little urine.
   Explain how the loop of Henle produces a low water potential in the tissue fluid of the medulla.3 marks