CAIE A Level Biology 9700 · Photosynthesis
A researcher investigates the fate of carbon fixed during photosynthesis in a plant. She supplies the plant with carbon dioxide labelled with radioactive carbon-14 for a short period, then transfers the plant to unlabelled CO2. She measures the appearance of radioactivity in various compounds over time. Describe how the carbon from CO2 is incorporated into Calvin cycle intermediates and subsequently used to build carbohydrates and amino acids.
5 marks, so the mark scheme is looking for about 5 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.