DP Biology (first assessment 2025)

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Question 21N.2.SL.TZ0.a

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Date November 2021 Marks available [Maximum mark: 4] Reference code 21N.2.SL.TZ0.a
Level SL Paper 2 Time zone TZ0
Command term Draw Question number a Adapted from N/A
a.
[Maximum mark: 4]
21N.2.SL.TZ0.a

Draw labelled diagrams to show the structure of RNA nucleotides and how they are linked together to form a molecule of RNA.

[4]

Markscheme

a. ribose drawn as pentagon and labelled sugar/ribose;
b. base drawn with correct link to (C1 of) ribose and labelled base/nitrogenous base;
c. phosphate drawn with correct link to (C5 of) ribose and labelled P/phosphate;
d. two (or more) ribonucleotides drawn with correct link (C3 to C5)

Examiners report

Many candidates were able to draw the structure of an RNA nucleotide and link it correctly by a 5’ to 3’ bond to another nucleotide. The commonest error was to show two strands of nucleotides linked by base pairing, indicating confusion between RNA and DNA.

Syllabus sections