Topic 1.2.2 - Disaccharides

Question 1

What are disaccharides made from?

Answer 1

2 monosaccharides

Question 2

What reaction joins the 2 monosaccharides?

Answer 2

Condensation

Question 3

What type of bond joins the monosaccharides together to form a disaccharide?

Answer 3

Glycosidic bond

Question 4

What molecule is removed in the formation of a disaccharide?

Answer 4

Water

Question 5

What 2 monosaccharides form sucrose?

Answer 5

alpha glucose and fructose

Question 6

What 2 monosaccharides form lactose?

Answer 6

alpha glucose and beta galactose

Question 7

What 2 monosaccharides form maltose?

Answer 7

alpha glucose and alpha glucose

Question 8

Is sucrose a reducing sugar?

Answer 8

no

Question 9

Name 3 reducing sugars

Answer 9

fructose
ribose
maltose
lactose

Question 10

Test for reducing sugars

Answer 10

1) Add benedict’s solution containing copper ions
2) Heat in a water bath
3) Reducing sugar reacts with the benedict’s and reduces copper ions to a +1 charge
4) Colour change from blue to brick red

Question 11

Test for non- reducing sugars

Answer 11

1) Heat the non reducing sugar with a few drops of HCl
2) Neutralise with sodium carbonate
3) Produces monosaccharides which will give a positive benedict’s test

Question 12

Why do we add HCl to a non reducing sugar?

Answer 12

Hydrolyses glycosidic bonds

Question 13

3 main disaccharides

Answer 13

Sucrose
maltose
lactose