DP Biology (last assessment 2024)
Question 18M.2.SL.TZ1.6a
| Date | May 2018 | Marks available | [Maximum mark: 4] | Reference code | 18M.2.SL.TZ1.6a |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 4]
18M.2.SL.TZ1.6a
(a)
Outline the role of the parts of an alveolus in a human lung.
[4]
Markscheme
a. the (spherical) wall of an alveolus maximizes/allows gas exchange
b. pneumocytes I (optimize) gas exchange
c. pneumocytes II produce surfactant
d. adjacent capillaries enclose alveolus for efficient gas exchange with blood
e. surfactant reduces surface tension/prevents collapse of alveolus
f. (alveolar) macrophages/phagocytes help with defense/homeostasis/response to foreign substances
