3.1.1: Monomers, polymers and carbohydrates

Question 1

What is hydrolysis?

Answer 1

1. Breaks a chemical bonds between two
   molecules;
2. Using water;

Question 2

What is a condensation reaction?

Answer 2

1. Creates a chemical bond
2. Removing a molecule of water

Question 3

Describe Glycogens Structure (3)

Answer 3

1. Polysaccharide of α-glucose;
2. (Joined by) glycosidic bonds;
3. Branched structure

Question 4

compare glycogen with cellulose (4)

Answer 4

1. Cellulose is made up of β-glucose
   (monomers) and glycogen is made up of α-
   glucose (monomers);
2. Cellulose molecule has straight chain and
   glycogen is branched;
3. Cellulose molecule has straight chain and
   glycogen is coiled;
4. Glycogen has 1,4- and 1,6- glycosidic bonds
   and cellulose has only 1,4- glycosidic bonds

Question 5

Explain Glycogen’s structure
related to function (5)

Answer 5

1. Insoluble (in water), so doesn’t affect water
   potential;
2. Branched / coiled / (α-)helix, so makes
   molecule compact;
3. Polymer of (α-)glucose so provides glucose
   for respiration;
4. Branched / more ends for fast breakdown /
   enzyme action;
5. Large (molecule), so can’t cross the cell
   membrane

Question 6

Relate 3 of starch’s properties to its
function (6)

Answer 6

1. Insoluble;
2. Don’t affect water potential;
3. Helical;
4. Compact;
5. Large molecule;
6. Cannot leave cell

Question 7

Describe the Test for reducing sugar

Answer 7

1. Heat with Benedict’s reagent (1);
2. colour change from blue to brick-red (1)

Question 8

Describe the Test for a non reducing sugar

Answer 8

1. Heat with Benedict’s reagent and no colour
   change (1);
2. boil with acid (HCl) and then neutralise with
   (NaHCO3) (1);
3. re- heat with Benedict’s reagent and colour
   change from blue to brick-red (1)

Question 9

Describe the Test for starch

Answer 9

1. Add iodine in potassium iodide solution (1);
2. colour change from brown to blue-black (1)