Topic 1.2 Lipids

Question 1

What elements are lipids made up of?

Answer 1

Carbon, hydrogen and oxygen

Question 2

Name the two types of lipids.

Answer 2

Fats and oils

Question 3

Are lipids soluble or insoluble?

Answer 3

Soluble in non-polar solvents, insoluble in water

Question 4

What are some of the functions of lipids?

Answer 4

Source of energy, membrane component, waterproofing, hormones, energy storage, insulation

Question 5

What are triglycerides made up of?

Answer 5

A glycerol molecule and three fatty acids

Question 6

What is the reaction in which triglycerides are formed?

Answer 6

A condensation reaction

Question 7

What are the bonds between the glycerol and fatty acids?

Answer 7

Ester bonds

Question 8

How is the reaction sped up?

Answer 8

Enzymes

Question 9

What is the structure of a fatty acid?

Answer 9

Acid group at one end with a hydrocarbon chain attached

Question 10

What is the difference between a saturated and an unsaturated fatty acid?

Answer 10

Saturated has no double bonds but an unsaturated fatty acid has double bonds

Question 11

Are saturated fats oils or solids?

Answer 11

Solids

Question 12

Are unsaturated fats oils or solids?

Answer 12

Oils, because the double bond lowers their melting point

Question 13

What does monounsaturated mean?

Answer 13

Just one double bond in the chain

Question 14

What does polyunsaturated mean?

Answer 14

Many double bonds

Question 15

How does a C=C bond affect the shape of a fatty acid?

Answer 15

Puts a kink in the hydrocarbon chain which causes it to bend

Question 16

Why are saturated fatty acids more likely to be solid?

Answer 16

Because the straight chains make them closer so there are stronger intermolecular forces between them

Question 17

Why are unsaturated fatty acids more likely to be liquid?

Answer 17

Because the double bonds creates a bigger distance between the chains so the intermolecular forces are weaker

Question 18

What are the three roles of lipids?

Answer 18

Energy storage, waterproofing and insulation

Question 19

When do triglycerides release energy?

Answer 19

When they’re oxidised in respiration

Question 20

How are lipids better energy stores than carbohydrates?

Answer 20

They release twice as much energy so they’re more concentrated energy stores

Question 21

In what kind of animals are fat stores found?

Answer 21

In animals that go long periods of time without food and must rely on their energy store

Question 22

Why do lipids repel water?

Answer 22

Because they’re hydrophobic

Question 23

How is lipids’ waterproof property used?

Answer 23

Oils are secreted by the sebaceous glands in the skin of mammals so the fur of the animal becomes oily and therefore water-repellent

Question 24

How are lipids used as insulation?

Answer 24

Stored in mammals as adipose tissue (subcutaneous fat). Blood doesnt circulate to this tissue so heat isnt transferred there so the heat of the body stays near the core which means there is a smaller heat gradient so heat isnt lost as quickly

Question 25

Compare the structure of phospholipids to triglycerides

Answer 25

Same structure except one of the fatty acid groups is attached to phosphate group

Question 26

Is a phospholipid group hydrophillic or hydrophobic?

Answer 26

The head is hydrophillic bc of the phosphate group forming hydrogen bonds with the water. The fatty acid chains are hydrophobic

Question 27

How do phospholipids form a monolayer?

Answer 27

When phospholipids come in contact with water the heads dissolve in water and the tails stick out