CAIE A Level Biology 9700 · Energy and respiration
A student investigated the respiratory quotient (RQ) of germinating mung beans using a simple respirometer. The following results were obtained over a 2-hour period:
| Time (min) | O2 absorbed (cm³) | CO2 released (cm³) |
|---|---|---|
| 0 | 0 | 0 |
| 60 | 1.2 | 1.2 |
| 120 | 2.4 | 2.4 |
Describe what the RQ value indicates about the respiratory substrate being used by the germinating mung beans and explain why this is advantageous for the seeds.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.