Scheme of Work Cambridge International as & a level

2.2.2 Define the terms monomer, polymer, macromolecule, monosaccharide, disaccharide and polysaccharide.

2.2.3 State the role of covalent bonds in joining smaller molecules together to form polymers.

2.2.4 State that glucose, fructose and maltose are reducing sugars and that sucrose is a non-reducing sugar.

2.2.5 Describe the formation of a glycosidic bond by condensation, with reference to disaccharides, including sucrose, and polysaccharides.

2.2.6 Describe the breakage of a glycosidic bond in polysaccharides and disaccharides by hydrolysis, with reference to the non-reducing sugar test.

2.2.7 Describe the molecular structure of the polysaccharides starch and glycogen and relate their structures to their functions in living organisms.

2.2.8 Describe the molecular structure of the polysaccharide cellulose and outline how the arrangement of cellulose molecules contributes to the function of plant cell walls.

Help learners refresh their knowledge of light microscopy by hosting a brief multiple-choice quiz with questions taken from past Cambridge IGCSE (or equivalent) papers. Learners can ‘vote’ for their choice of answer by holding up their hand when you call out ‘A,’ ‘B,’ ‘C’ or ‘D.’ You could use this activity to formatively assess learners before they begin. (F)

Provide each learner with a piece of poster paper and provide guidance to help them draw a molecule of

Tell learners that they will each represent a molecule of glucose. They should each hold a ball (or balloon) in their right hand and then link hands (or arms) but only when they have thrown the ball away. This emphasises the loss of water when forming polymers. The ‘water molecules’ can then be collected, counted, and used to show why the process is called condensation. Extend thinking by describing the other reducing sugars as monomers that can form maltose and the non-reducing sugars.

This topic requires learners to interpret numerous structural equations. Learners can discover how to draw these structures and how they change during biochemical reactions. However, it is harder to put this into words. Encourage learners to describe a condensation reaction between two glucose residues (low demand) or how β -glucose residues are arranged in cellulose relative to one another (high demand), and how the arrangement of cellulose molecules contributes to the function of plant cell walls. A useful animation is at:

Learners draw a table or Venn diagram to show which monosaccharides combine into disaccharides, and the type of monosaccharides and bonds in polysaccharides, as a useful summary. (F)

Learners write the shortest sentence possible using the following key terms: polysaccharide, polymer, sugar, glycosidic. This is a good way to focus learners on developing their higher-order thinking skills to make sense of the meaning of these terms, rather than simply recall them. (F)