Question 23M.3.HL.TZ1.10
| Date | May 2023 | Marks available | [Maximum mark: 4] | Reference code | 23M.3.HL.TZ1.10 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Explain, Outline, State | Question number | 10 | Adapted from | N/A |
There are many biological pigments.
Anthocyanins are pigments that can be used as pH indicators.
Explain which form of the anthocyanin, X or Y, predominates at a pH of 12.
[1]
X AND «high pH moves» equilibrium left
OR
X AND loss of proton/H+ «at high pH/due to excess OH−(aq)»
OR
X AND positive ion unlikely «at high pH» ✓
State one factor, other than pH, that can affect the stability of anthocyanins.
[1]
temperature OR light ✓
Outline one structural similarity and one structural difference between hemoglobin and myoglobin.
Similarity:
Difference:
[2]
Similarity:
heme group
OR
Fe cation/Fe2+ ✓
Difference:
myoglobin has one polypeptide chain AND hemoglobin has four polypeptide chains
OR
myoglobin has one heme «group» AND hemoglobin has four heme «groups»
OR
myoglobin has no quaternary structure AND hemoglobin has quaternary structure ✓
Accept both are globular proteins or both are metalloproteins.
Do not accept both are polymers of amino acids.