1.3 Carbohydrates - disaccharides and polysaccharides

Question 1

List 3 common examples of disaccharides.

Answer 1

lactose
sucrose
maltose

Question 2

what happens when water is added to a disaccharide under suitable conditions?

Answer 2

The glycosidic bond is broken which releases the constituent monosaccharides.

Question 3

How is maltose formed?

Answer 3

condensation of two glucose molecules

Question 4

How is lactose formed?

Answer 4

condensation of a glucose molecule and a galactose molecule

Question 5

How is sucrose formed?

Answer 5

condensation of a glucose molecule and a fructose molecule

Question 6

what are the 2 types of glucose?

Answer 6

a-glucose

b-glucose

Question 7

List 3 common examples of polysaccharides.

Answer 7

Starch
Glycogen
Cellulose

Question 8

What are starch, glycogen and cellulose classed as?

Answer 8

polysaccharides

Question 9

How do you test for starch?

Answer 9

iodine test

Question 10

describe how to perform a iodine test, and what results show a positive outcome?

Answer 10

combine iodine solution with sample to be tested.

Positive result indicated by a change of colour from orange/yellow to blue/black

Question 11

how is starch formed?

Answer 11

The joining of between 200 and 100,000 a-glucose molecules by glycosidic bonds in a series of condensation reactions.

Question 12

describe how glycogen is formed.

Answer 12

lots of branched chains of a-glucose

Question 13

What is a glycosidic bond?

Answer 13

covalent chemical bonds that link carbohydrates to other molecules .

Question 14

describe how starch is formed.

Answer 14

chains of a-glucose monosaccharides linked by glycosidic bonds