Question 20N.3.SL.TZ0.b
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.3.SL.TZ0.b |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Outline | Question number | b | Adapted from | N/A |
To investigate whether carbon dioxide is required for photosynthesis, a plant was irrigated using water from which carbon dioxide had been removed and was then placed in the apparatus shown in the diagram. The apparatus was left in darkness for 24 hours to destarch the leaves. Then, after several hours in light, a leaf was removed from the plant and found to contain no starch when tested. A control was performed using a second plant. A leaf from this plant tested positive for starch.
[Source: © International Baccalaureate Organization 2020.]
Outline how the carbon dioxide could be removed from the water used to irrigate the plant.
[1]
a. boiling (and cooling) the water;
b. expose the water to a vacuum;
Allow distillation of water.
There were many suggestions on how carbon dioxide could be removed from water despite boiling the water being an assessment statement.
