Lipids

Question 1

What elements do lipids contain?

Answer 1

Carbon, hydrogen, and oxygen

Question 2

Are lipids soluble in water?

Answer 2

No, lipids are insoluble in water

Question 3

In what type of solvents are lipids soluble?

Answer 3

Organic solvents, e.g., alcohol

Question 4

Name two types of lipids.

Answer 4

Triglycerides and phospholipids

Question 5

What is the structure of a triglyceride molecule?

Answer 5

3 fatty acids joined to one glycerol molecule

Question 6

How are fatty acids joined to glycerol in triglycerides?

Answer 6

Through three condensation reactions with the loss of three water molecules

Question 7

What type of bond forms between glycerol and a fatty acid?

Answer 7

Ester bond

Question 8

How many ester bonds are present in one triglyceride molecule?

Answer 8

3 ester bonds

Question 9

Are triglycerides and phospholipids considered polymers?

Answer 9

No, they are not polymers

Question 10

What is the general formula of a fatty acid?

Answer 10

R-COOH

Question 11

What does ‘R’ represent in the fatty acid formula?

Answer 11

A long hydrocarbon chain

Question 12

What is the characteristic of saturated fatty acids?

Answer 12

No double bonds between the carbon atoms

Question 13

What defines unsaturated fatty acids?

Answer 13

One or more double bonds between the carbon atoms

Question 14

What is a method to hydrolyze lipids?

Answer 14

Heating or using water

Question 15

What type of group is present in phospholipids?

Answer 15

Phosphate group

Question 16

Fill in the blank: The R group in fatty acids can vary, leading to different types of _______.

Answer 16

Fatty acids

Question 17

True or False: Triglycerides are made up of similar monomers.

Answer 17

False

Question 18

What happens during the condensation reaction forming triglycerides?

Answer 18

Loss of water molecules

Question 19

What type of reaction is involved in the formation of an ester bond?

Answer 19

Condensation reaction

Question 20

What are lipids soluble in?

Answer 20

Lipids are soluble in organic solvents.

Lipids do not dissolve in water.

Question 21

What process hydrolyzes lipids into fatty acids and glycerol?

Answer 21

Hydrolysis of lipids can occur by heating with acid or alkali or using the enzyme lipase.

The hydrolysis process involves breaking ester bonds.

Question 22

What is the energy release comparison between triglycerides and carbohydrates during aerobic respiration?

Answer 22

Triglycerides release twice as much energy as carbohydrates.

This is due to their high proportion of carbon-hydrogen bonds.

Question 23

What is metabolic water and why is it important for organisms in dry deserts?

Answer 23

Metabolic water is released when triglycerides are respired, important for hydration in dry environments.

It results from the high ratio of hydrogen to oxygen in triglycerides.

Question 24

Why are triglycerides considered ideal storage compounds?

Answer 24

Triglycerides are non-polar and insoluble in water, making them osmotically inactive.

This property prevents water retention in cells.

Question 25

Where are triglycerides present that helps reduce water loss?

Answer 25

Triglycerides are present in the waxy cuticle of insects and plant leaves. ## Footnote Their insolubility helps minimize evaporation.

Question 26

What do phospholipids contain that distinguishes them from other lipids?

Answer 26

Phospholipids contain a phosphate group. ## Footnote This characteristic differentiates them from triglycerides.

Question 27

What components make up a phospholipid molecule?

Answer 27

A phospholipid molecule consists of one glycerol, two fatty acids, and a phosphate group. ## Footnote These components are joined by condensation reactions forming ester bonds.

Question 28

What is the structure of the phospholipid molecule?

Answer 28

The phospholipid molecule has a polar hydrophilic head and a non-polar hydrophobic tail. ## Footnote The head attracts water, while the tail repels it.

Question 29

Fill in the blank: A phospholipid consists of a glycerol, two fatty acids, and a _______.

Answer 29

phosphate group.

Question 30

True or False: Phospholipids are soluble in water.

Answer 30

False. ## Footnote The hydrophobic tail of phospholipids makes them insoluble in water.

Question 31

What is the structure of phospholipids in cell membranes?

Answer 31

They form a bilayer due to hydrophobic tails being repelled by water.

Question 32

What is the emulsion test used for?

Answer 32

To detect lipids in a sample.

Question 33

What are the steps involved in the emulsion test for lipids?

Answer 33

* Place a small amount of the sample into a test tube with ethanol * Shake the mixture to dissolve the fat * Add the mixture to water in another test tube and mix * A white emulsion of fat droplets indicates lipid presence.

Question 34

What are the common characteristics of both triglycerides and phospholipids?

Answer 34

* Insoluble in water * Contain glycerol * Contain ester bonds * Contain C, H, and O * Phospholipids also contain P

Question 35

How many fatty acids are present in triglycerides and phospholipids?

Answer 35

Triglycerides have three fatty acids; phospholipids have two fatty acids plus a phosphate group.

Question 36

What is the polarity of triglycerides and phospholipids?

Answer 36

* Triglycerides are hydrophobic/non-polar * Phospholipids have hydrophilic and hydrophobic regions.