Lipids

Question 1

Name 3 characteristics lipids share

Answer 1

• contain C, H, O2
• insoluble in water
• soluble on organic solvents

Question 2

What are the two main groups of lipids?

Answer 2

1. triglycerides

2. phospholipids

Question 3

Name five roles of lipids.

Answer 3

• contribute to flexibility of membranes
• source of energy when oxidised
• protection of organs
• waterproofing as they are insoluble
• insulation

Question 4

What is the bond formed between a fatty acid an glycerol?

Answer 4

ester bond

condensation reaction

Question 5

What is a triglyceride?

Answer 5

3 fatty acids + glycerol molecule

Question 6

What is a fatty acid?

Answer 6

carboxyl group + hydrocarbon chain

Question 7

What is the difference between saturated and non-saturated?

Answer 7

saturated means there are NO double bonds between C atoms (C=C)

Question 8

Name 4 advantages of the structure of triglycerides.

Answer 8

• high ratio of energy storing C-H bonds: C atoms
• low mass:energy ratio making the good storage molecules
• high H:O ratio as they release h20 when oxidised
• insoluble in water

Question 9

How is a phospholipid different to a triglyceride?

Answer 9

phospholipids replace 1 fatty acid with a phosphate molecule

Question 10

Which part of a phospholipid is hydrophilic?

Answer 10

phosphate molecule

Question 11

Which part of a phospholipid is hydrophobic?

Answer 11

2 fatty acids

Question 12

How does the structure of phospholipids relate to their properties?

Answer 12

• polar molecule allows them to form a bilayer in cell-surface membrane
• can form glycolipids by combining with carbohydrates

Question 13

Test for lipids

Answer 13

emulsion test

Question 14

what colour shows the presence of a lipid?

Answer 14

cloudy-white