Biological Molecules

Question 1

Describe how you would test for non - reducing sugars ?

Answer 1

Heat sample with dilute hydrochloric acid in a water bath. Neutralise with soudium hydrogencarbonate. Then carry out Benedict’s test

Question 2

Describe the structure of starch and explain how it helps their function?

Answer 2

DESCRIBE : 2 Polymer chains, Amylose creates an unbranched helix and Amylopectin creates the branched chain.
EXPLAIN : Helix - compact and can fit lots of glucose in a small space
Branched - enables rapid hydrolysis to convert starch back into glucose as creates large SA
Insoluble - no effect on water potential

Question 3

Describe the structure of cellulose and explain how it helps their function?

Answer 3

DESCRIBE : Long unbranched straight chains held in parallel by hydrogen bonds to form fibrils.
EXPLAIN : Many HB - collective strength
Insoluble - no effect on water potential

Question 4

Describe the structure of glycogen and explain how it helps their function?

Answer 4

DESCRIBE : Highly branched molecule
EXPLAIN : Branched - enables rapid hydrolysis to convert starch back into glucose as creates large SA
Insoluble - no effect on water potential

Question 5

What is the difference between a saturated fatty acid and an unsaturated fatty acid ?

Answer 5

Unsaturated fatty acid has at least one double and between the carbon atoms in their hydrocarbon chain