DP Biology (last assessment 2024)

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Question 21M.1.SL.TZ2.10

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Date May 2021 Marks available [Maximum mark: 1] Reference code 21M.1.SL.TZ2.10
Level SL Paper 1 Time zone TZ2
Command term Question number 10 Adapted from N/A
10.
[Maximum mark: 1]
21M.1.SL.TZ2.10

Bacteria cultured in a medium containing only 15N were transferred to a medium containing only 14N and allowed to complete one round of replication. The DNA in bacteria produced as a result of replication on the 14N medium was extracted and subjected to caesium chloride centrifugation which separates DNA molecules according to their density.

Which centrifuge tube shows the arrangement of bands observed after one round of replication?

A. Tube 3

B. Tube 4

C. Tube 5

D. Tube 6

[1]

Markscheme

D

Examiners report

The candidates found this question difficult, but it did discriminate well. This was a common question with HL and the HL students performed better than SL on the question as would be expected.

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