Biochemistry 2

Which two of the groups, 1-4, in the image, combine to form a peptide link?

• 1 and 2

• 1 and 3

• 2 and 3

• 3 and 4

1 Water has the formula H₂O, and a relative molecular mass of 18. Hydrogen sulfide has the formula H₂S, and a relative molecular mass of 34. At room temperature water is a liquid whereas hydrogen sulfide is a gas. How can this difference in state be explained?

• the difference in molecular mass of the two molecules

• covalent bonding

• ionic bonding

• hydrogen bonding

How many fatty acid chains are found in a phospholipid?

• 1

• 2

• 3

• 4

1 Which of the following is not a protein?

• antibody

• membrane-carrier molecule

• keratin

• amylose

1 If the biuret reagents are added to starch, what will the resulting colour be?

• pale blue

• blue-black

• brick red

• purple

Which of these chemical groups is not hydrophilic?

• -CH2CH3

• -COOH

• -NH2

• -OH

The first step in the test for a lipid is to add ethanol or propanone.

What does this step do?

• dissolve the lipid

• hydrolyse the lipid

• emulsify the lipid

• esterify the lipid

Consider the following properties of water,

1 high specific heat capacity

2 high latent heat of vaporisation

3 high tensile strength

4 high surface tension

5 low viscosity

6 high electrical conductance.

Which combination of these properties is important in the movement of water through a plant and the cooling effects of transpiration?

• 1 3 5 6

• 1 4 5 6

• 2 3 4 5

• 2 3 5 6

Polysaccharides are synthesised in plants by which of the following processes?

• condensation

• hydrolysis

• oxidation

• reduction

Which one of the following types of bond is principally responsible for holding the α-helix shape of a protein secondary structure?

• disulfide

• peptide

• ionic

• hydrogen