Glycogen and cellulose are polymers. Fig. 2.1 shows small, representative regions of a glycogen molecule and a cellulose molecule.

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

1. [3] if only one molecule described, statement of difference must be in context of glycogen any three from: glycogen branched (v cellulose unbranched); monomer is / made of, alpha- / α-, glucose (v cellulose monomer is ẞ-glucose); (1,4- and) 1, 6-. glycosidic bond(s) (v cellulose 1,4-glycosidic bond(s)); alternate, monomers / glucose residues / 1,4-(glycosidic) bonds, are not, rotated 180° / inverted / flipped / AW ; ora
2. [3] any three from: 1 glycogen is a store of, energy/ glucose ; R produces energy 2 idea that many, branching points / 'ends' / terminals, for easy / faster, addition / release, of glucose ; 3 compact so stores much, glucose / energy (in cells / small space); 4 insoluble ; 5 does not, lower / change, water potential (of cell); A no osmotic effect 6 AVP; e.g. prevents loss of glucose from cell (chemically) inactive so does not take part in cell metabolism / AW
3. [3] any three from: 1 unbranched (polymer) / straight chain / linear; 2 cellulose molecules are arranged in parallel ; 3 idea that large number of -OH groups (projecting in all directions); 4 allows, hydrogen bonds / H-bonds, to form with water or makes molecule hydrophilic ; 5 many hydrogen bonds between cellulose molecules / AW ; 6 cellulose molecules form microfibrils; I ‘fibrils' / fibres 7 hydrogen bonds give high tensile strength to microfibrils A cellulose fibres / cell wall or hydrogen bonds help cell walls to resist, turgor pressure / AW ;