CAIE A Level Biology 9700 · Energy and respiration
A study compared the energy released from the complete oxidation of 1 g of glucose (a carbohydrate) and 1 g of triacylglycerol (a lipid). The lipid released more than twice the energy per gram compared to glucose. With reference to the chemical composition of these substrates and the process of aerobic respiration, explain why lipids contain more energy per gram than carbohydrates.
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.
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.