| Date | May 2013 | Marks available | 1 | Reference code | 13M.1.HL.TZ1.26 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Question number | 26 | Adapted from | N/A |
Question
A channel protein is used to transport ions across a membrane. What would you expect to find lining the inside of the channel?
A. Phospholipids
B. Non-polar amino acids
C. Fatty acids
D. Polar amino acids
Markscheme
D
Examiners report
Question 26 was answered correctly by fewer candidates than expected. Channel proteins are needed for facilitated diffusion of charged and polar substances, so polar amino acids can be expected to line their pores
