1.3 Disaccharides And Polysaccharides

Question 1

Disaccharide definition

Answer 1

A pair of monosaccharides joined by a glycosidic bond in a condensation reaction

Question 2

Polysaccharide definition

Answer 2

Polymers they are formed by the condensation of many monosaccharides

Question 3

Glucose + glucose -> ?

Answer 3

Maltose

Question 4

Glucose + fructose -> ?

Answer 4

Sucrose

Question 5

Glucose + galactose -> ?

Answer 5

Lactose

Question 6

Glycosidic bond definition

Answer 6

Bond between 2 monosaccharides

Question 7

Condensation reaction between 2 alpha glucose

Answer 7

Page 10

Question 8

Condensation reaction between 2 beta glucose

Answer 8

See red book

Question 9

Hydrolysis reaction of alpha maltose

Answer 9

Page 10

Question 10

Hydrolysis reaction of beta maltose

Answer 10

See red book

Question 11

Test for starch

Answer 11

• add potassium iodide/ iodine
• shake
• blue- black solution, if present

Question 12

Test for non- reducing sugars

Answer 12

• add Benedict’s reagent and heat
• stays blue
• add HCl and heat
• hydrolysis
• break glycosidic bonds
• add NaHCO3
• neutralise HCl
• add Benedict’s reagent and heat
• brick red precipitate, if present

Question 13

2 properties of polysaccharides

Answer 13

• insoluble

- very large

Question 14

What is the colour of potassium iodide/ iodine?

Answer 14

Yellow- brown

Question 15

Why does starch turn iodine from yellow- brown to blue- black?

Answer 15

Iodine molecules can become trapped within the ‘coils’ of the Amylose chain