DP Chemistry (last assessment 2024)

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Question 18N.3.sl.TZ0.12b

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.3.sl.TZ0.12b
Level sl Paper 3 Time zone TZ0
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 2]
18N.3.sl.TZ0.12b

The structure of penicillin is shown in section 37 of the data booklet.

(b)

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.

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