DP Chemistry (last assessment 2024)
Question 18N.3.hl.TZ0.b
| Date | November 2018 | Marks available | [Maximum mark: 2] | Reference code | 18N.3.hl.TZ0.b |
| Level | hl | Paper | 3 | Time zone | TZ0 |
| Command term | Explain | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
18N.3.hl.TZ0.b
The structure of penicillin is shown in section 37 of the data booklet.
Explain how the open β-lactam ring kills bacteria.
[2]
Markscheme
«irreversibly» binds/bonds to enzyme/transpeptidase
OR
inhibits enzyme/transpeptidase «in bacteria» that produces cell walls
OR
prevents cross-linking of bacterial cell walls ✔
cells absorb water AND burst
OR
cells cannot reproduce ✔
Accept “reacts with” for “bonds to” for M1.
Do not accept “cell membrane” for “cell wall” for M1.
Accept “cells burst due to osmotic pressure” for M2.
Accept “bacteria” for “cells” for M2.
