Practise O/L exam questions on Human Body Functions with worked solutions
2023 · Paper II · 6 marks
The diagram shows a nephron (kidney tubule).
(i) State the two main functions of the kidney.
(ii) Describe what happens during filtration in the glomerulus.
(iii) Name TWO substances that are selectively reabsorbed in the proximal convoluted tubule.
(iv) Name the hormone that controls the amount of water reabsorbed by the kidney.
Show worked solution
(i) Excretion of nitrogenous waste (urea); Osmoregulation (control of water balance in blood).
(ii) High blood pressure in the glomerulus forces small molecules (water, glucose, urea, salts) out of the capillaries into the Bowman's capsule. Large molecules (proteins, blood cells) remain in the blood.
(iii) Glucose and amino acids (also accept water, Na⁺).
(iv) ADH (Antidiuretic hormone / Vasopressin).