Question 19M.3.sl.TZ2.7a(i)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.sl.TZ2.7a(i) |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Deduce | Question number | a(i) | Adapted from | N/A |
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]
phosphodiester correctly drawn [✔]
both ester groups correctly drawn [✔]
Note: Accept protonated phosphate.
Accept phosphodiester in centre position.
This was very poorly answered. Although the phosphodiester was a challenging mark it could be awarded in both the protonated and deprotonated form. The two esters should have been much more straight forward mark, and both were required to receive the second mark. Students struggled with proper structural drawings for both marks and many students simply left this question blank. The functional groups did need to be drawn out in their full structural form to receive the mark as indicated in the question.
