Chapter 4

Question 1

What chemical elements make up carbohydrates?

Answer 1

Carbon, Hydrogen, Oxygen

Question 2

What chemical elements make up fats and oils?

Answer 2

Carbon, Hydrogen, Oxygen (lesser than in carbs)

Question 3

What chemical elements make up proteins?

Answer 3

Carbon, Hydrogen, Oxygen, Nitrogen

Question 4

Monomers of each biological molecule

Answer 4

Carbohydrates: Glucose
Fats and oils: 3 fatty acids and one glycerol molecule
Proteins: chains of 20 diff amino acids

Question 5

Polymers of carbohydrates

Answer 5

Glycogen: animal starch (energy store)
Starch: insoluble for storage
Cellulose: long fibres to form a cell wall

Question 6

Use of Fats and Oils (Lipids)

Answer 6

insulation
source of energy (twice as much as carbs)
formation of cell membranes

Question 7

Uses of Proteins

Answer 7

enzymes
hormones
growth
formation of cell membranes

Question 8

Test for starch

Answer 8

Add a few drops of iodine
Turns from brown to blue-black

Question 9

Test for reducing sugars

Answer 9

Add equal amounts of Benedicts solution and boil/heat
Gradual color change according to amount of reducing sugar
Blue → Green-Yellow → Orange → Red

Question 10

Test for fats and oils

Answer 10

Dissolve in ethanol
Add to distilled water
White emulsion

Question 11

Test for proteins

Answer 11

Add equal amount sodium hydroxide and mix
Add few drops 1% copper sulfate
Violet halo forms

Question 12

Test for Vitamin C

Answer 12

Measure 2.0cm³ DCPIP solution into a test tube
Add drop by drop, shake after each
DCPIP decolorizes

Question 13

What is the structure of DNA

Answer 13

2 nucleotide strands coiled together to form a double helix
Each strand has a sugar phosphate backbone along with bases : A/T or C/G