CAIE A Level Biology 9700 · Homeostasis
A student examines a stained longitudinal section of a mammalian kidney under a light microscope. The outer region (cortex) appears darker due to many glomeruli, the inner region (medulla) contains loops of Henle and collecting ducts, and the renal pelvis collects urine. The student also identifies a Bowman's capsule and a proximal convoluted tubule. Describe how the structures of the kidney and the nephron are adapted for ultrafiltration and selective reabsorption.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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