Sugars

Question 1

Monosaccharide Definition

Answer 1

The monomers of carbohydrates.

Question 2

Disaccharide Definition

Answer 2

Two monosaccharides joined together by a glycosidic bond.

Question 3

Polysaccharide Definition

Answer 3

Many monosaccharides joined by a glycosidic bond.

Question 4

4 examples of monosaccharides

Answer 4

Alpha glucose, Beta glucose, Fructose, Galactose.

Question 5

Monosaccharides in the disaccharide maltose:

Answer 5

2X alpha glucose

Question 6

Monosaccharides in the disaccharide sucrose:

Answer 6

Alpha glucose + fructose

Question 7

Monosaccharides in the disaccharide lactose:

Answer 7

Alpha glucose + galactose

Question 8

Alpha glucose ( diagram )

Question 9

Beta glucose ( diagram )

Question 10

Formation of a disaccharide + diagram

Answer 10

Two monosaccharides joined in a condensation reaction. Glycosidic bond created between. Formation of water.

Question 11

Testing for reducing sugars:

Answer 11

1. add benedict’s reagent
2. boil in a water bath
3. blue -> brick red precipitate is a positive result

Question 12

Testing for a non - reducing sugar:

Answer 12

1. initially test for reducing sugar but if sample remains blue then discard
2. with a new sample add dilute hydrochloric acid ( HCl )
3. neutralise with an alkali ( sodium hydrogen carbonate )
4. carry out steps for testing for a reducing sugar
5. blue -> brick red precipitate is a positive result

Question 13

Examples of reducing sugars:

Answer 13

• all of the monosaccharides
• maltose
• lactose

Question 14

Examples of a non reducing sugar:

Answer 14

sucrose

Question 15

How to determine the concentration of the reducing sugar?

Answer 15

Compare to a colour standard chart.

Question 16

How to determine the concentration of the reducing sugar?

Answer 16

Compare to a colour standard chart.