Question 21M.2.SL.TZ2.4a
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.2.SL.TZ2.4a |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | State | Question number | a | Adapted from | N/A |
State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.
[1]
a. (aerobic/cellular) respiration ✔
b. gas exchange / diffusion ✔
Do not accept photosynthesis.
Do not accept breathing
Organism is taken to be a living thing.
In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO2 or HCO3 from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.
