Question 19N.3.sl.TZ0.d(i)
| Date | November 2019 | Marks available | [Maximum mark: 2] | Reference code | 19N.3.sl.TZ0.d(i) |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Identify, State | Question number | d(i) | Adapted from | N/A |
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]
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”.
