| Date | May 2015 | Marks available | 1 | Reference code | 15M.1.HL.TZ1.26 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 26 | Adapted from | N/A |
Question
Which describes the role of amino acids in the channels of membrane proteins used for facilitated diffusion?
A. Polar amino acids create a channel through which hydrophilic molecules can pass.
B. Polar amino acids create a channel through which hydrophobic molecules can pass.
C. Non-polar amino acids create a channel through which hydrophilic molecules can pass.
D. Non-polar amino acids create a channel through which hydrophobic molecules can pass.
Markscheme
A
Examiners report
This was answered less successfully than expected. Many candidates thought that channel proteins are used to convey hydrophobic molecules across a membrane when it is hydrophilic particles whose diffusion has to be facilitated.
