2. Biological Molecules

Question 1

Benedict’s test for reducing sugars

Question 2

Iodine test for starch

Question 3

Emulsion test for lipids

Question 4

Biuret test for proteins

Question 5

Semi-quantitive Benedict’s test for concentration of reducing sugar solution

Answer 5

Time to first colour change
Compare to colour standards

Question 6

Test to identify presence of a non-reducing sugar

Answer 6

Boil with acid for 1 minute, then neutralise with base before boiling with equal volume of Benedict’s solution for 5 minutes to test for presence of reducing sugars that might’ve been formed by the hydrolysis of a non-reducing sugar catalysed by the acid.

Question 7

Alpha-glucose vs. Beta-glucose

Answer 7

-OH group up or down on the first carbon, assuming 6th carbon is up: alpha-glucose has the -OH group down, while beta-glucose has the -OH group up.

Question 8

Monomer

Question 9

Polymer

Question 10

Macromolecule

Question 11

Monosaccharide

Question 12

Disaccharide

Question 13

Polysaccharide

Question 14

List the names of 3 reducing sugars

Answer 14

glucose, fructose, maltose

Question 15

State the name of a non-reducing sugar

Answer 15

sucrose

Question 16

Formation of a glycosidic bond

Answer 16

By condensation; -OH groups of neighbouring reducing sugars bind to form a bond between the two molecules, with an oxygen as the link; 1 molecule of water is released in the process;

Question 17

Breakage of a glycosidic bond

Answer 17

By hydrolysis;