DP Biology (last assessment 2024)
Question 17N.3.HL.TZ0.22b
| Date | November 2017 | Marks available | [Maximum mark: 4] | Reference code | 17N.3.HL.TZ0.22b |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 4]
17N.3.HL.TZ0.22b
The micrograph shows a section of cardiac muscle.
[Source: Musculocardiaco by Goyitrina (https://commons.wikimedia.org/wiki/File:Musculocardiaco.jpg)]
(b)
Describe the unique properties of cardiac muscle cells.
[4]
Markscheme
a. cells are myogenic/self-excitatory
b. cells are joined end to end
OR
cells are joined by intercalated disc
c. «intercalated discs» allow for faster propagation «of signal»
d. cells contract together for coordinated contraction
e. contain many mitochondria
f. cells are branching/Y-shaped
g. controlled by pacemaker/sinoatrial/SA and atrioventricular/AV nodes
[Max 4 Marks]
