DP Biology (first assessment 2025)
Question 20N.2.SL.TZ0.6a
| Date | November 2020 | Marks available | [Maximum mark: 3] | Reference code | 20N.2.SL.TZ0.6a |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Draw | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 3]
20N.2.SL.TZ0.6a
(a)
Draw the ultrastructure of a prokaryotic cell based on electron micrographs.
[3]
Markscheme
a. cell wall;
b. plasma membrane; Clearly shown as a separate line under the cell wall or the inner line
c. cytoplasm AND 70S ribosomes; Do not allow (small) circles
d. nucleoid/naked DNA;
e. plasmid
OR
pili
OR
flagella/flagellum;
Structures correctly drawn and labelled.
Award [2 max] if any exclusively eukaryotic structures are shown.
Do not allow cilia as they are not found in prokaryotes.
Examiners report
In part (a) many candidates were penalised for drawing clear eukaryotic structures such as mitochondria. The general level of the drawings was better than in the past. However a prokaryote should not be represented as a square. Ribosomes must be shown as dots, not circles.
