DP Chemistry (last assessment 2024)
Question 19M.3.sl.TZ2.b
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.sl.TZ2.b |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
19M.3.sl.TZ2.b
Phosphatidylcholine is an example of a phospholipid found in lecithin.
Lecithin is a major component of cell membranes. Describe the structure of a cell membrane.
[2]
Markscheme
phospholipid bilayer/double layer
OR
two layers of phospholipids [✔]
polar/hydrophilic heads facing aqueous environment AND non-polar/hydrophobic tails facing away from aqueous environment [✔]
Note: Award [2] for a suitably labelled diagram.
Award [1 max] for a correct but unlabelled diagram.
Accept “polar/hydrophilic heads on outside AND non-polar/hydrophobic tails on inside for M2.
Examiners report
This question was another one where the first mark was fairly well answered but the explanation or second mark was often not correct or complete.
