DP Chemistry (last assessment 2024)
Question 18M.3.hl.TZ2.b
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.3.hl.TZ2.b |
| Level | hl | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 3]
18M.3.hl.TZ2.b
Explain how the structure of vitamin A is important to vision using section 35 of the data booklet.
[3]
Markscheme
vitamin A oxidized to «11-cis-»retinal
extended conjugation
OR
extensive delocalization
cis-retinal converts to trans-retinal through absorption of light
Accept “vitamin A/hydroxyl/hydroxy/alcohol/CH2OH group oxidized to aldehyde/CHO «group in retinal»”.
[3 marks]
