Question 19M.2.SL.TZ1.c
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.2.SL.TZ1.c |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Describe | Question number | c | Adapted from | N/A |
HGH is a peptide hormone. Describe the mode of action of peptide hormones on target cells.
[3]
a. peptide hormones do not enter the cell ✔
b. they bind to receptors/proteins in the plasma membrane of the target cell ✔
c. a secondary messenger initiates the cell response ✔
d. causes a cascade of actions that changes the cell’s physiology ✔
e. cAMP is a common secondary messenger ✔
Although a few students still confused peptide and steroid hormones, many were able to score 2 or 3 marks here. Most of these students stated that peptide hormones do not enter the cell due to their hydrophilic nature, that they do bind to receptors on the cell membrane, and that this binding initiates a secondary messenger and causes a cascade of reactions. This level of detailed knowledge was not seen elsewhere in the paper. One possible reason for this is that peptide and steroid hormones have appeared frequently on recent exam papers, and that the use of past papers remains the most common way for students to prepare for these exams.
