DP Biology (first assessment 2025)

Test builder »

Question 22N.2.HL.TZ0.5c

Select a Test
Date November 2022 Marks available [Maximum mark: 2] Reference code 22N.2.HL.TZ0.5c
Level HL Paper 2 Time zone TZ0
Command term Explain Question number c Adapted from N/A
c.
[Maximum mark: 2]
22N.2.HL.TZ0.5c
(c)

Explain the role of the hormone ADH in osmoregulation.

[2]

Markscheme
  1. ADH secreted if blood is hypertonic/solute concentration too high/water content too low/dehydrated;
  2. aquaporins open/more aquaporins in (plasma membranes of cells in DCT/collecting duct) with ADH;
  3. DCT/collecting duct becomes more permeable to water/reabsorbs more water (from filtrate);
Examiners report

This was generally well answered. A few candidates thought that ADH could both increase and decrease water reabsorption in the nephron. The commonest omission was hypertonic conditions being the signal that results in ADH secretion.

Syllabus sections