State the chemical composition of a glucose molecule.

Explain how glucose molecules combine to form disaccharides and polysaccharides.

Outline the function of glucagon in relation to the breakdown of glycogen when fasting.

Describe the strengths of the ATP-CP system with regard to the re-synthesis of ATP during a 50-metre sprint.

CHO «1:2:1»

OR

carbon hydrogen oxygen ✔

occurs with a condensation reaction
OR
glucose molecules bond together to form disaccharide/polysaccharide molecules with the loss of water ✔

each polysaccharide molecule contains many «tens/hundreds» of monosaccharides joined «through dehydration synthesis reactions» ✔

when two monosaccharides are attached together they do so by means of a glycosidic bond «and this results in the formation of a disaccharide»
OR
a glycosidic bond is the essential bond that provides the backbone of larger carbohydrate molecules ✔

joining two –OH groups results in a disaccharide «containing an –O– bridge between the 2 monosaccharide units» ✔

Accept in the form of a diagram.

fasting reduces blood glucose which stimulates the release of glucagon ✔

glucagon is a hormone released by the pancreas when blood sugar levels are low ✔

glucagon increases the blood glucose level when it falls below normal levels ✔

glucagon accelerates the conversion of glycogen in the liver into glucose/promotes glycogenolysis ✔

glucagon promotes glucose formation from amino acids ✔

allows ADP to gain a phosphate molecule very quickly/almost instantaneously so recovery time is quick ✔

does not require oxygen ✔

the CP is readily available «inside skeletal muscle» ✔

provides energy for explosive high intensity exercise/movement ✔

no fatiguing by-products ✔

This question was answered very well. Many candidates were able to give the specific chemical formula for glucose.

Many candidates were able to identify that a condensation reaction occurs and this causes a release of a water molecule. However, many candidates struggled to gain a second mark for this question. Further detail of the condensation reaction process is required.

Many candidates understood the role of glucagon; however many believed that glycogen breakdown to glucose is called glycogenesis. Therefore specific advice should be given to candidates to help them understand the key difference between similar key terms. Some candidates failed to focus on the question regarding fasting. Some candidates became confused between glucagon and glycogen.

Many candidates could describe the ATP-PC system but struggled to analyse the strengths of the energy system. Very few candidates gained two marks for this question.