DP Biology (first assessment 2025)

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Question 19M.2.SL.TZ2.6b

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Date May 2019 Marks available [Maximum mark: 3] Reference code 19M.2.SL.TZ2.6b
Level SL Paper 2 Time zone TZ2
Command term Draw Question number b Adapted from N/A
b.
[Maximum mark: 3]
19M.2.SL.TZ2.6b
(b)

Draw the structure of a dipeptide.

[3]

Markscheme

a. two amino acids, one with NH2/NH3+ end and one with COOH/COO– end ✔

b. peptide bond between C=0 and N—H correctly drawn ✔

c. «chiral» C with H and R group on each amino acid ✔

d. peptide bond labelled/clearly indicated between C terminal of one amino acid and N terminal of the second amino acid ✔

Labels not required for amino group and carboxyl group.

Examiners report

Students were successful at indicating the presence of two chiral carbons. Commonly the carboxyl group was represented as an aldehyde group. Nitrogen atoms were commonly shown as having just two bonds.

Syllabus sections