lipids

Question 1

What elements are found in lipids?

Answer 1

Carbon, hydrogen, and oxygen (with much less oxygen than carbohydrates).

Question 2

Are lipids soluble in water?

Answer 2

No, they are insoluble in water.

Question 3

In what solvents are lipids soluble?

Answer 3

Organic/non-polar solvents like alcohol (ethanol) and acetone.

Question 4

What are simple lipids called?

Answer 4

Triglycerides.

Question 5

What is a triglyceride made of?

Answer 5

Three fatty acid molecules and one glycerol molecule.

Question 6

What is the formula of glycerol?

Answer 6

C3H8O3.

Question 7

What are the properties of glycerol?

Answer 7

Sweet and colorless.

Question 8

What is a fatty acid?

Answer 8

A long hydrocarbon chain with a carboxyl (-COOH) functional group.

Question 9

What is the difference between saturated and unsaturated fatty acids?

Answer 9

Saturated fatty acids have no C=C double bonds (straight, compact chains); Unsaturated fatty acids have one or more C=C double bonds (bent chains, take up more space).

Question 10

Are fatty acids hydrophilic or hydrophobic?

Answer 10

Hydrophobic.

Question 11

How is a triglyceride formed?

Answer 11

Through condensation reactions between glycerol and three fatty acids.

Question 12

What type of bond links glycerol and fatty acids?

Answer 12

Ester bond.

Question 13

What are the two main types of triglycerides?

Answer 13

Fats and oils.

Question 14

What type of fatty acids do oils contain?

Answer 14

Unsaturated fatty acids.

Question 15

What are the properties of oils?

Answer 15

Contain C=C double bonds, shorter fatty acid chains, lower melting point and molecular weight, liquid at room temperature.

Question 16

What type of fatty acids do fats contain?

Answer 16

Saturated fatty acids.

Question 17

What are the properties of fats?

Answer 17

No C=C double bonds, longer fatty acid chains, higher melting point and molecular weight, solid at room temperature.

Question 18

Why are fats stored in adipose cells?

Answer 18

They are too large to diffuse through cell membranes and insoluble in water to affect water potential in them.

Question 19

Why are triglycerides good for energy storage?

Answer 19

They contain more C-H bonds per gram than carbohydrates, yielding twice as much energy.

Question 20

Why are lipids a lightweight energy source?

Answer 20

They provide more energy per gram, making them useful for animals that rely on speed or flight.

Question 21

Why are carbohydrates used more often than lipids for energy?

Answer 21

Carbohydrates are metabolized faster, both aerobically and anaerobically.

Question 22

Where are lipids found in plants and animals?

Answer 22

Oil in seeds (plants), fats in mammals.

Question 23

Why do hibernating animals store fat?

Answer 23

It serves as a food reserve when food is scarce in cold seasons.

Question 24

How do lipids act as heat insulators?

Answer 24

They conduct heat slowly, preventing heat loss.

Question 25

Where is lipid-based insulation found?

Answer 25

Blubber in polar bears, whales, and under human skin.

Question 26

How do lipids provide buoyancy?

Answer 26

They are less dense than water.

Question 27

Where is lipid-based buoyancy important?

Answer 27

Large aquatic mammals like whales and seals.

Question 28

How do lipids provide protection?

Answer 28

They absorb shock and surround delicate organs like the heart and kidneys.

Question 29

What is the function of lipids in nerve cells?

Answer 29

They form the myelin sheath, acting as an electrical insulator for rapid impulse transmission.

Question 30

What is metabolic water?

Answer 30

Water produced from the oxidation of triglycerides during respiration.

Question 31

Why are lipids a better source of metabolic water than carbohydrates?

Answer 31

They contain more hydrogen atoms, releasing more water when used for respiration.

Question 32

Which animals rely on metabolic water?

Answer 32

Camels and kangaroo rats in dry, hot environments.

Question 33

What fat-soluble vitamins do lipids dissolve?

Answer 33

Vitamins A, D, E, and K.

Question 34

What are compound lipids?

Answer 34

Lipids that contain additional components, such as phospholipids.

Question 35

What are phospholipids made of?

Answer 35

Two fatty acids, one glycerol molecule, and a phosphate group.

Question 36

Which part of a phospholipid is hydrophilic?

Answer 36

The phosphate group.

Question 37

Which part of a phospholipid is hydrophobic?

Answer 37

The fatty acid tails.

Question 38

How do phospholipids arrange in the cell membrane?

Answer 38

They form a bilayer with hydrophilic heads facing outwards and hydrophobic tails facing inwards.

Question 39

What is the function of phospholipids in cells?

Answer 39

They are a major component of biological membranes.

Question 40

What test is used to detect fats?

Answer 40

Ethanol emulsion test.

Question 41

What indicates the presence of fats in the ethanol emulsion test?

Answer 41

A white emulsion.

Question 42

What are the steps for the ethanol emulsion test with liquid food?

Answer 42

1. Add 2 cm³ of ethanol to 2 cm³ of food solution. 2. Shake thoroughly. 3. Add 2 cm³ of water. 4. Shake and observe.

Question 43

What are the steps for the ethanol emulsion test with solid food?

Answer 43

1. Chop food into small pieces. 2. Place in dry test tube. 3. Add 2 cm³ of ethanol and shake. 4. Allow solids to settle. 5. Decant ethanol into another test tube with 2 cm³ of water. 6. Shake and observe.