DP Chemistry (last assessment 2024)
Question 19M.3.sl.TZ1.7a
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.sl.TZ1.7a |
| Level | sl | Paper | 3 | Time zone | TZ1 |
| Command term | Draw | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 2]
19M.3.sl.TZ1.7a
Starch is a natural polymer of glucose.
(a)
Draw the structure of the repeating unit of starch and state the type of linkage formed between these units.
Type of linkage:
[2]
Markscheme
continuation bonds AND -O- attached to just one end AND both H-atoms on end carbons must be on the same side [✔]
Note: Square brackets not required.
Ignore “n” if given.
Mark may be awarded if a polymer is shown but with the repeating unit clearly identified.
Type of linkage:
glycosidic [✔]
Note: Accept “ether”.
Examiners report
Hardly any students were able to draw the required repeating unit, but in contrast almost all knew that the monomers were joined by a glycosidic linkage.
