Lipids

Question 1

Lipids

Answer 1

Biological molecules made of carbon, hydrogen and oxygen that are only soluble in organic solvents such as alcohols

Question 2

What are the two states lipids can present themselves in?

Answer 2

Fats and oils

Question 3

What are two common uses of lipids?

Answer 3

Hormones and respiratory substances

Question 4

What are the two types of lipids?

Answer 4

Triglycerides and phospholipids

Question 5

What makes lipids insoluble in water?

Answer 5

They contain fatty acid tails that are hydrophobic and contain lots of chemical energy

Question 6

What is the bond formed in triglycerides?

Answer 6

Ester bond

Question 7

How many molecules of water are formed in the formation of a triglyceride?

Answer 7

Three molecules due to the three reactions that take place

Question 8

What state are triglycerides usually found in?

Answer 8

Fats

Question 9

Saturated lipids (SSS)

Answer 9

Fatty acids that don’t contain any carbon-carbon double bonds and are usually found in animal fats

Question 10

Unsaturated lipids (DUL)

Answer 10

Fatty acids that contain carbon-carbon double bonds and are usually found in plants

Question 11

What can occur to saturated lipids?

Answer 11

The molecule is able to bend due to the presence of a double bond and therefore they cannot pack together as tightly

Question 12

What state are unsaturated lipids usually found in?

Answer 12

Oils since they are liquid at room temperature

Question 13

Why are triglycerides an excellent energy store?

Answer 13

Because they contain a high ratio of energy-storing carbon-hydrogen bonds to carbon atoms

Question 14

Why are triglycerides a good storage molecule?

Answer 14

Because they have a low mass to energy ratio so they have a lot of energy stored in a small volume

Question 15

Why are lipids insoluble in water?

Answer 15

Because they are large and non-polar and so their storage doesn’t affect the water potential of cells

Question 16

Why are triglycerides an important source of water for organisms that live in dry environments?

Answer 16

Because they have a high ratio of hydrogen-oxygen atoms so they can release water when they are oxidised

Question 17

What state are phospholipids usually found in?

Answer 17

Waxes

Question 18

What describes phosphate heads?

Answer 18

Hydrophilic as they love water

Question 19

What structure do phospholipids form when they are in contact with water?

Answer 19

A polar micelle that presents itself as an insoluble droplet

Question 20

Where are phospholipids commonly found?

Answer 20

In cell membranes as the hydrophilic phosphate heads are used to remain at the surface to provide structure

Question 21

What structure do phospholipids form when they are in an aqueous environment?

Answer 21

A phospholipid bilayer

Question 22

Why is it important that the centre of the phospholipid bilayer is hydrophobic?

Answer 22

Because it makes sure water-soluble substances can’t pass through

Question 23

Which test is used to detect the presence of lipids?

Answer 23

Emulsion test

Question 24

What does a positive result of the emulsion test look like?

Answer 24

A cloudy white milky emulsion will form