DP Biology (first assessment 2025)

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Question 19M.1B.SL.TZ1.c

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.1B.SL.TZ1.c
Level SL Paper 1B Time zone TZ1
Command term Explain Question number c Adapted from N/A
c.
[Maximum mark: 2]
19M.1B.SL.TZ1.c

Explain how the amphipathic nature of phospholipids allows them to form bilayers.

[2]

Markscheme

a. amphipathic means that they are both hydrophilic and hydrophobic ✔ 

b. the outside hydrophilic parts are exposed to water ✔ 

c. hydrophobic parts are away from water in the inside ✔

Water or lack of needs to be mentioned for mpb 

Examiners report

The terms hydrophilic and hydrophobic were commonly stated, although sometimes assigned to heads and tails incorrectly; however this was not penalised. Orientation towards or away from water was less often explained.

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