A-LevelBiologyHomeostasis9700/42 · Feb/Mar 2023 · Q110 Marks

Fig. 1.1 is a drawing of a longitudinal section (LS) of a human kidney. [Figure 1.1]

(a)Use the letters A, B, C and D in Fig. 1.1 to complete Table 1.1. Each letter may be used once, more than once or not at all. For each description, list all the letters that are correct. Table 1.1 description location of loops of Henle location of Bowman's capsules location of glomeruli contains urine at final concentration region of kidney[4]
(b)The volume and water potential of the urine produced by the kidney vary according to the water potential of the blood. This is a result of osmoregulation. Describe the role of aquaporins in osmoregulation.[3]
(c)Describe the role of the brain in osmoregulation when the water potential of the blood increases above the set point.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2023). The mark or mark type is shown in brackets.

[4] (a) location of loops of Henle C ;
[4] (a) location of Bowman's capsules A ;
[4] (a) location of glomeruli A ;
[4] (a) contains urine at final concentration B + D ;
[3] (b) any three from:
[3] (b) 1 (aquaporins are) water channel (proteins) ;
[3] (b) 2 (more) aquaporins increase (cell surface) membrane permeability (to water); ora
[3] (b) 3 of collecting duct (cells) ; I distal convoluted tubule cells
[3] (b) 4 allow water to, be reabsorbed / move into tissue fluid or blood;
[3] (c) any three from:
[3] (c) 1 detected by osmoreceptors ;
[3] (c) 2 in hypothalamus ;
[3] (c) 3 (osmoreceptors send) fewer impulses to posterior pituitary; I signals
[3] (c) 4 less ADH, released / produced ; I no ADH released

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.