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Question 22N.1.SL.TZ0.11

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Date November 2022 Marks available [Maximum mark: 1] Reference code 22N.1.SL.TZ0.11
Level SL Paper 1 Time zone TZ0
Command term Question number 11 Adapted from N/A
11.
[Maximum mark: 1]
22N.1.SL.TZ0.11

Cells were grown in heavy nitrogen (15N) for many generations and then grown in light nitrogen (14N) for two rounds of DNA replication. Which diagram shows the result of the centrifuged DNA?

[1]

Markscheme

D

Examiners report

This question required students to recognise the pattern of bands that would appear after two rounds of replication in the Meselson Stahl experiment. This question discriminated poorly with more candidates opting for responses A and C than for D, the correct response. This was surprising as 2.7 of the guide states  'Analysis of Meselson and Stahl's results to obtain support for the theory of semi-conservative replication of DNA', and this was a straightforward question on this content. 

Syllabus sections