Lipids

Question 1

What are the functions of lipids?

Answer 1

Storage
EFA
Energy store
Electrical insulation
Waterproofing
Production of metabolic water
Protection
Buoyancy
Hormone production
Thermal insulation

Question 2

Why are lipids good energy store?

Answer 2

They have a high proportion of H atoms relative to O atoms so they yield more energy than the same mass of carbohydrate

Question 3

Why are lipids a good storage molecule?

Answer 3

Lipids are non polar and are insoluble in water and it has more energy per gram than carbohydrates

Question 4

What are biological membranes made of?

Answer 4

Phospholipids

Question 5

What are EFA’s?

Answer 5

Essential fatty acids that the body needs but can’t synthesise

Question 6

How are lipids used for waterproofing?

Answer 6

Waxy cuticles prevent excess evaporation from the surface of the leaf

Question 7

Why are lipids used for buoyancy?

Answer 7

They can float on water, so they can maintain buoyancy in organisms

Question 8

How are lipids used in hormone production?

Answer 8

Steroid hormones such as oestrogen needs lipids in its formation, as other substances like plant growth hormones

Question 9

How are lipids used in thermal insulation?

Answer 9

Fat conducts heat very slowly so having a layer underneath the skin keeps metabolic heat on

Question 10

What elements are lipids made up of?

Answer 10

Carbon, Hydrogen and Oxygen

Question 11

What is the most common type of lipids?

Answer 11

Triglyceride

Question 12

What are the properties of fats (not lipid fats)

Answer 12

Solid at room temperature
Single carbon bonds
Saturated chains

Question 13

What are the properties of oils?

Answer 13

Liquid at room temperature
Double carbon bonds
Unsaturated chains

Question 14

What makes ups a triglyceride?

Answer 14

3 fatty acid chains
1 glycerol

Question 15

what are the structures in a fatty acid chain

Answer 15

An acid group and a hydrocarbon chain

Question 16

What is a saturated chain?

Answer 16

A hydrocarbon chain with only single carbon bonds

Question 17

What is an unsaturated chain?

Answer 17

A hydrocarbon chain with at least one double carbon bond

Question 18

How does a glycerol bond with the 3 fatty acids?

Answer 18

The glycerol and fatty acids go through a condensation reaction between the H of the glycerol and the fatty acids OH to make an ester bond

Question 19

Can the fatty acid tails be different?

Answer 19

Yes

Question 20

What makes up a phospholipid?

Answer 20

It has 1 glycerol, 2 fatty acids and 1 phosphate ion

Question 21

What part of the phospholipid is hydrophobic?

Answer 21

The fatty acid tails

Question 22

What part of the phospholipid is hydrophilic and why?

Answer 22

The phosphate head because it is polar

Question 23

Why is part of the phospholipid hydrophobic and why?

Answer 23

The fatty acid tails is non-polar

Question 24

Why part of the phospholipid is hydrophilic?

Answer 24

The phosphate group is polar

Question 25

What happens to a phospholipid when it goes in water?

Answer 25

The phosphate group is soluble in water and the fatty acids stick out from the water

Question 26

What shapes do phospholipid groups make in water?

Answer 26

Micelle, a sphere with the phosphate head on the outside touching the water, and the fatty acids on the inside A bilayer with the phosphate on the outside and the fatty acids on the inside. It is 2 phospholipid layers.

Question 27

What does cholesterol do in the cell membrane?

Answer 27

It stabilises the cell membranes fluidity and permeability

Question 28

What does cholesterol do with hormones synthesis?

Answer 28

It is the base of some hormones such as oestrogen and testosterone

Question 29

Is cholesterol polar?

Answer 29

No but the OH group on one of the rings is

Question 30

Can cholesterol based hormones pass through the cell membrane and why?

Answer 30

Yes, because it is non-polar

Question 31

What produces cholesterol?

Answer 31

The liver

Question 32

What is the plant version of cholesterols?

Answer 32

Stigmasterol