3.1 Biological Molecules:

Question 1

3.1.3 Lipids

Describe how a triglyceride is formed. (3)

Answer 1

1. One glycerol and three fatty acids.
2. Condensation reactions and removal of 3 water molecules.
3. Ester bonds are formed.

Question 2

3.1.3 Lipids

Describe how an ester bond is formed in a phospholipid molecule. (2)

Answer 2

1. Condensation reaction
2. between glycerol and fatty acid.

Question 3

3.1.3 Lipids

Describe how you would test a piece of food for the prescence of a lipid. (2)

Answer 3

1. Add ethanol then add water and shake
2. White / milky emulsion = positive test.

Question 4

3.1.3 Lipids

The scientist expressed their results as Percentage of lipid in plasma membrane by mass. Explain how they would find these values. (2)

Answer 4

1. Divide mass of each lipid by total mass of all lipids.
2. Multiply answer by 100.