CAIE A Level Biology 9700 · Energy and respiration
A researcher supplies a culture of yeast cells with glucose labelled with carbon-14 on carbon atom 1. After a short time, the cells are lysed and radioactive pyruvate is detected. Explain how the carbon atoms from the labelled glucose become incorporated into pyruvate during glycolysis. Include in your answer the key stages of glycolysis and the location where it takes place.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.