DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ1.8a

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ1.8a
Level hl Paper 3 Time zone TZ1
Command term Draw Question number a Adapted from N/A
a.
[Maximum mark: 2]
19M.3.hl.TZ1.8a

Starch is a natural polymer of glucose.

(a)

Draw the structure of the repeating unit of starch and state the type of linkage formed between these units.

Type of linkage:

[2]

Markscheme

continuation bonds AND −O attached to just one end AND both H atoms on end carbons must be on the same side    [✔]


Type of linkage:
glycosidic    [✔]

 

Note: Square brackets not required.

Ignore “n” if given.

Mark may be awarded if a polymer is shown but with the repeating unit clearly identified.

Accept “ether”.

 

Examiners report

Candidates were required to draw the structure of the repeating unit of starch given the ring structure as a starting point. This proved extremely difficult with very few candidates scoring a mark. Commonly, the structure of a -glucose was given, or an attempt was made to draw a polymer. Naming the type of linkage formed was answered well.

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