Glucose and galactose are examples of monosaccharides. State one other example of a monosaccharide.

There are several different types of carbohydrate. State which type of carbohydrate lactose is.

State the type of chemical reaction that occurs when lactose is digested into glucose and galactose.

Simple laboratory experiments show that when the enzyme lactase is mixed with lactose, the initial rate of reaction is highest at 48°C. In food processing, lactase is used at a much lower temperature, often at 5°C. Suggest reasons for using lactase at relatively low temperatures.

fructose/ribose/deoxyribose/ribulose/other monosaccharides apart from glucose and galactose

disaccharide

hydrolysis

less denaturation / enzymes last longer at lower temperatures;
lower energy costs / less energy to achieve 5° C compared to 48° C;
reduces bacterial growth / reduces (milk) spoilage;
to form products more slowly / to control rate of reaction;

Candidates were often correct, but some stated a disaccharide instead of a monosaccharide. Common errors were sucrose or maltose.

Most candidates correctly identified lactose as a disaccharide.

Hydrolysis was often given, yet some erred by stating decomposition.

Generally answered well with most candidates referring to denaturation and/or controlling the rate of reaction.