CAIE A Level Biology 9700 · Energy and respiration
A researcher incubates a cell-free extract of rat muscle with glucose labelled with [14C] at all six carbon positions. After a short time, the researcher analyses the products and detects [14C] only in pyruvate and not in any other metabolite. Describe the events of glycolysis that lead to this outcome. Use your answer to explain the fate of the carbon atoms from glucose.
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.