| Date | November 2016 | Marks available | 1 | Reference code | 16N.3.SL.TZ0.1 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Suggest | Question number | 1 | Adapted from | N/A |
Question
In an experiment measuring oxygen consumption, a laboratory mouse was placed in a respirometer for a short time. Soda lime solution absorbed any carbon dioxide produced during the experiment.
Suggest the purpose of the wire mesh.
Describe how the apparatus measures the oxygen consumption of the mouse
Discuss whether the apparatus would be suitable for measuring the oxygen consumption of a small green plant during respiration.
Markscheme
a. allow gases to pass between mouse and soda lime
b. prevent mouse getting in contact with soda lime
c. prevent mouse from being in contact with faeces/urine/droppings
a. more oxygen in inhaled air than in exhaled air
OR
mouse uses oxygen in respiration
b.carbon dioxide exhaled / produced by mouse is absorbed by the soda lime
Source/mouse must be mentioned for marking point b – not just “soda-lime absorbs C02”.
c. difference in volume is oxygen used by mouse
OR
the volume/concentration/pressure of oxygen in the jar falls
d. «this» sucks the coloured liquid up the tube
e. volume of oxygen consumed equals the increase in volume of coloured water in the tube
a. oxygen released during photosynthesis
b. plants use carbon dioxide (released by respiration)
c. if carbon dioxide is too low in concentration then photosynthesis will be eliminated/reduced
d. results in an inaccurate/low measure of the oxygen that is consumed
e. perform experiment in dark to prevent photosynthesis
OR
cover bell jar to exclude light to prevent photosynthesis
Do not accept plants convert carbon dioxide to oxygen.
