DP Biology (first assessment 2025)
Question 21N.2.HL.TZ0.4b
| Date | November 2021 | Marks available | [Maximum mark: 2] | Reference code | 21N.2.HL.TZ0.4b |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
21N.2.HL.TZ0.4b
(b)
Describe the secondary structure of proteins.
[2]
Markscheme
a. polypeptide wound into a helical structure / alpha/α helix
OR
polypeptide folded back on itself forming a pleated sheet / beta/β pleated sheet;
b. stabilized/held in shape by/due to hydrogen bonds (between C=O and N-H groups);
c. secondary structures are regular/unvarying (within polypeptides/proteins);
Allow annotated diagrams
Examiners report
There were some good answers here describing secondary structures and the role of hydrogen bonding.
