CarbohydratesEdexcel A-Level Biology B: Mind map

Exam questions on Carbohydrates

1. A brewing technician is studying how barley grains are converted into fermentable sugars. Barley grains store starch. When the grains germinate, enzymes break the starch down into maltose, which is then broken down further so that yeast can ferment the sugars.
   Describe what happens when a molecule of maltose is hydrolysed.2 marks
2. A biochemistry student is drawing the structures of three monosaccharides. She draws α-glucose, β-glucose and ribose, the sugar found in RNA.
   Ribose, maltose and glycogen are all carbohydrates. Classify each as a monosaccharide, a disaccharide or a polysaccharide, and state how these three groups differ in structure.2 marks
3. A student is investigating milk. Lactose is the main carbohydrate in milk. A dairy company treats milk with an enzyme that hydrolyses lactose, producing 'lactose-free' milk for customers who cannot digest lactose.
   Describe how a molecule of lactose is formed from its monomers.3 marks