Chemical Composition

Question 1

How are lipids different from carbohydrates

Answer 1

Lipids have a much higher ratio of hydrogen atoms to oxygen atoms

Question 2

What solvents are lipids soluble/insoluble in

Answer 2

Soluble: alcohol, ether, chloroform (organic)
Insoluble: water

Question 3

State the type of lipids

Answer 3

1. Fats
2. Waxes
3. Phospholipids
4. Steroids

Question 4

Fats and oils are triglycerides. Explain what is triglycerides and how is it formed

Answer 4

Triglycerides are a type of ester formed from condensation of one glycerol molecule with three molecules of fatty acid

Question 5

How can you test the presence of fats? What results does it show when the presence of lipids is positive?

Answer 5

Ethanol emulsion test. A white emulsion will be formed

Question 6

What are the types of fatty acid? Compare and contrast. (3 each)

Answer 6

Saturated f.a. and unsaturated f.a.

Similarities

• carbon, hydrogen, oxygen elements
• glycerol and fatty acids
• contain nonpolar molecules

Differences:

1. s: single bond between carbon
   - u: at least one double bond
2. s: × form chemical bond with additional hydrogen atoms (all bonds between carbon atoms are saturated)
   - u: still can receive one or more additional hydrogen atoms (carbon atoms are unsaturated)
3. s: solid form at room temperature
   - u: liquid form at room temperature
4. s: source: butter and animal fat
   - u: source: olive and fish oil

Question 7

Why is saturated fats not good for health

Answer 7

• raises cholesterol level in blood in the form of low-density lipoprotein (LDL)
• increase risk of heart attack and diabetes

Question 8

Define wax and state its importance

Answer 8

• Contains one molecule of alcohol that combines with another molecule of fatty acid and is waterproof
• covers the epidermis leaves (cuticles) + sebum secretes by skin

Question 9

Define phospholipid

Answer 9

Major component of plasma membrane, made up of one molecule of glycerol, combine with two molecules of fatty acids and one group of phosphate

Question 10

Define steroids and give examples

Answer 10

• lipids that X contain fatty acids

- cholesterol, testosterone, oestrogen, progesterone

Question 11

Functions of fats

Answer 11

• reserved energy
• protect internal organs
• heat insulator

Question 12

Function of glycolipids

Answer 12

• ensure stability of plasma membrane

- cell identification process

Question 13

Importance of cholesterol

Answer 13

• Steroid hormone synthesis

- strengthens the phospholipid bilayer, making it more flexible and less permeable to water-soluble substances