lipids

Question 1

the general structure of a fatty acid is RCOOH.
name the group represented by COOH. (1)

Answer 1

carboxyl;

Question 2

the R group is unsaturated.
explain why. (1)

Answer 2

double bond between carbon atoms in hydrocarbon chain;

Question 3

describe how you would test for the presence of a lipid in a liquid sample of food. (2)

Answer 3

1. add ethanol/alcohol then add water and shake/mix;
2. white/milky emulsion;

Question 4

describe how a triglyceride is formed. (3)

Answer 4

1. one glycerol and three fatty acids;
2. condensation reactions and removal of three molecules of water;
3. ester bonds formed;

Question 5

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

Answer 5

1. condensation reaction;
2. between of glycerol and fatty acid;

Question 6

describe how you would test a piece of food for the presence of lipid. (2)

Answer 6

1. dissolve in alcohol, then add water;
2. white emulsion shows presence of lipid;