Question 23M.3.SL.TZ1.1
| Date | May 2023 | Marks available | [Maximum mark: 4] | Reference code | 23M.3.SL.TZ1.1 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Predict, State, Suggest | Question number | 1 | Adapted from | N/A |
An experiment on aerobic respiration was performed using a plant in a pot containing fertile soil. The apparatus was set up as shown in the diagram. Sodium hydroxide and limewater (calcium hydroxide) are both alkaline solutions. Limewater goes cloudy when carbon dioxide is bubbled into it.
State the purpose of lime water in flask B.
[1]
to check there is no carbon dioxide (left in the air)/show any carbon dioxide present;
Do not accept absorb carbon dioxide
Suggest a reason that the pot was covered with a plastic bag.
[1]
soil releases CO2 from microorganisms/decomposers/bacteria/fungi
OR
respiration by microorganisms may affect the result;
Suggest a suitable control for this experiment.
[1]
using the same apparatus without a plant
OR
cover the whole plant with a plastic bag;
Do not accept a controlled variable
The same apparatus was used in another experiment, but the potted plant was exposed to light. Predict with a reason the results for lime water in flask C after one hour.
[1]
no change/limewater stays clear
OR
because plant takes in carbon dioxide by photosynthesis;
Do not accept references to oxygen produced by photosynthesis