DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ2.a(i)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ2.a(i) |
| Level | hl | Paper | 3 | Time zone | TZ2 |
| Command term | Deduce | Question number | a(i) | Adapted from | N/A |
a(i).
[Maximum mark: 2]
19M.3.hl.TZ2.a(i)
Phosphatidylcholine is an example of a phospholipid found in lecithin.
Phosphatidylcholine may be formed from propane-1,2,3-triol, two lauric acid molecules, phosphoric acid and the choline cation.
Deduce the structural formula of phosphatidylcholine.
[2]
Markscheme
phosphodiester correctly drawn [✔]
both ester groups correctly drawn [✔]
Note: Accept protonated phosphate.
Accept phosphodiester in centre position.
Examiners report
Almost all the candidates struggled with this part. Although the phosphodiester was a challenging mark it could be awarded in both the protonated and deprotonated form. The two ester groups were required for the second mark. Candidates were not able to draw correctly for both marks, and many left this question blank.
