Topic One

Question 1

Describe the structure of a starch molecule and explain how starch is adapted for its function in cells. [6]

Answer 1

STRUCTURE

1. made from a-glucose;
2. joined by condensation/removing molecule of water/glycosidic bond;
3. Mainly 1 : 4 glycosidic bonds;
4. Some 1-6 glycosidic bonds form branches;

HOW STRUCTURE IS ADAPTED TO FUNCTION
5. Chains are helical so they are compact;
6 starch is insoluble so it doesn’t affect osmotic pressure / water potential;
7. Starch is a large molecule so it cannot leave the cel