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Question 19N.3.hl.TZ0.c

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.hl.TZ0.c
Level hl Paper 3 Time zone TZ0
Command term Identify, State Question number c Adapted from N/A
c.
[Maximum mark: 2]
19N.3.hl.TZ0.c

Stearic acid (Mr = 284.47) and oleic acid (Mr = 282.46) have the same number of carbon atoms. The structures of both lipids are shown in section 34 of the data booklet.

State one similarity and one difference in composition between phospholipids and triglycerides.

Similarity:

Difference:

[2]

Markscheme

Similarity:

«derived from» propane-1,2,3-triol/glycerol/glycerin/glycerine

OR
«derived from» at least two fatty acids
OR
 contains ester linkages
OR
long carbon chains ✔

NOTE: Do not accept “two fatty acids as both a similarity and a difference”.
Do not accept just “hydrocarbon/carbon chains”.

 

Difference:

phospholipids contain two fatty acids «condensed onto glycerol» AND triglycerides three
OR
 phospholipids contain phosphate/phosphato «group»/residue of phosphoric acid AND triglycerides do not ✔

NOTE: Accept “phospholipids contain phosphorus AND triglycerides do not".
Accept “phospholipids are amphiphilic AND triglycerides are not” OR “phospholipids have hydrophobic tails and hydrophilic heads AND triglycerides do not”.

Syllabus sections