Question 19M.2.HL.TZ2.c
| Date | May 2019 | Marks available | [Maximum mark: 8] | Reference code | 19M.2.HL.TZ2.c |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | c | Adapted from | N/A |
Antidiuretic hormone is a peptide hormone that is produced in the hypothalamus. Explain its action in the human body.
[8]
a. Antidiuretic hormone plays a role in osmoregulation/regulating blood solute concentration ✔
b. acts on the collecting ducts of the kidney ✔
c. acts in «late» distal convoluted tubule ✔
d. hypothalamus detects plasma/blood osmolarity/solute concentration ✔
e. if plasma/blood is too concentrated/hypertonic, «posterior» pituitary releases Antidiuretic hormone ✔
f. Antidiuretic hormone stimulates insertion of aquaporins/water channels / increases permeability of collecting duct ✔
g. water moves «through aquaporins» by osmosis into the medulla/blood ✔
h. urine becomes more concentrated/smaller volume ✔
i. negative feedback occurs ✔ OWTTE for negative feedback acceptable.
j. if blood is hypotonic no Antidiuretic hormone is released ✔
k. water is not reabsorbed from the collecting ducts/permeability of the collecting duct decreases ✔
l. urine becomes more dilute/less concentrated / higher volume ✔
OWTTE for all mp.
This question was commonly very well answered. Common errors included muddling the roles of the hypothalamus and the pituitary gland in the production and release of Antidiuretic hormone. It was uncommon for students to include a discussion of negative feedback in their answers.
