DP Chemistry (last assessment 2024)

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Question 20N.3.sl.TZ0.6c

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.3.sl.TZ0.6c
Level sl Paper 3 Time zone TZ0
Command term Discuss Question number c Adapted from N/A
c.
[Maximum mark: 2]
20N.3.sl.TZ0.6c
Phospholipids are a main component of cell membranes.

 

(c)

Phospholipids help maintain cellular environments while fatty acid lipids have important roles in energy storage and electrical insulation. Discuss the structural properties of saturated fats needed for these roles.

[2]

Markscheme

Energy storage:
not water-soluble/no hydrogen/H bonding
OR
 less oxidized/more reduced
OR
 high energy stored in bonds
OR
 high «negative» enthalpy of combustion/oxidation ✔

Accept “potential energy” for “stored energy”.

Electrical insulator:
no delocalized electrons/conjugation ✔

Examiners report

Not well answered. In particular the first mark seemed particularly challenging for students. Even when at times wording wasn't enough to allow BOD for M2 it was evident the candidate had some idea but none for the first one. Non-polar allowed many students to score the second mark.

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