biological molecules exam questions

Question 1

how are the structures of cellulose and glycogen different? 3 marks

Answer 1

1. glycogen has a branched structure and forms coils, whereas cellulose is a straight chain
2. glycogen has both 1,4 and 1,6 glycosidic bonds
3. cellulose just has 1,4 glycosidic bonds
4. cellulose is made from beta-glucose monomers, whereas glycogen is made up of alpha-glucose monomers

Question 2

how does glycogen act as an energy source? 2 marks

Answer 2

1. glycogen can be hydrolysed to glucose
2. the glucose could then be used to release energy through the process of respiration

Question 3

name the monomer maltose is made from 1 mark

Answer 3

glucose

Question 4

explain how starch is adapted to its function in the cells of plants 3 marks

Answer 4

1. starch is insoluble in water, so can be stored without affecting the cell’s water potential
2. starch is helical in shape, making it compact for storage
3. starch is a large molecule, so is unable to leave the cell