Date | May 2017 | Marks available | 6 | Reference code | 17M.3.HL.TZ2.22 |
Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
Command term | Explain | Question number | 22 | Adapted from | N/A |
Question
Explain the role of receptors in mediating the action of both steroid and protein hormones.
Markscheme
a. receptors are proteins
steroid hormones: [3 max]
b. steroid hormones cross plasma membrane
c. bind to receptor «proteins» in the cytoplasm of the target cell
d. to form a receptor–hormone complex
e. «the receptor–hormone complex» promotes the transcription of specific genes
peptide hormones: [3 max]
f. peptide hormones bind to receptors in the plasma membrane of the target cell
g. binding of hormones to «membrane» receptors activates a cascade of reactions
h. mediated by a second messenger inside the cell
i. such as cAmp or Ca2+ calmodulin