1A.2 - Sugars

Question 1

What elements do all carbohydrates contain?

Answer 1

C, H and O.

Question 2

Define ‘monosaccharides’.

Answer 2

The monomers from which larger carbohydrates are made.

Question 3

Give 3 examples of monosaccharides.

Answer 3

Glucose, fructose and galactose.

Question 4

What type of sugar is glucose?

Answer 4

A hexose sugar.

Question 5

Define ‘hexose sugar’.

Answer 5

A monosaccharide with 6 carbon atoms in each molecule.

Question 6

State the two isomers of glucose.

Answer 6

Alpha glucose and beta glucose.

Question 7

Define ‘isomer’.

Answer 7

Molecules with the same molecular formula, yet their atoms are connected in a different way.

Question 8

Which way round are the H and OH on alpha glucose?

Answer 8

H

OH

Question 9

Which way round are the H and OH on beta glucose?

Answer 9

OH

H

Question 10

What do 2 monosaccharides form when they join together? What type of reaction occurs to do this?

Answer 10

A disaccharide.

A condensation reaction.

Question 11

What type of bond forms between 2 monosaccharides when a water molecule is released?

Answer 11

Glycosidic.

Question 12

How is maltose formed?

Answer 12

By condensation of 2 glucose molecules.

Question 13

How is sucrose formed?

Answer 13

By condensation of a glucose molecule and a fructose molecule.

Question 14

How is lactose formed?

Answer 14

By condensation of a glucose molecule and a galactose molecule.

Question 15

glucose + glucose –>

Answer 15

maltose

Question 16

glucose + fructose –>

Answer 16

sucrose

Question 17

glucose + galactose –>

Answer 17

lactose

Question 18

Describe the Benedict’s test for reducing sugars.

Answer 18

1) Heat the sample with the Benedict’s reagent.
2) If the sample stays blue, then there is no reducing sugar present.
3) If the sample forms a brick red precipitate, then there is a reducing sugar present (and there will be solid particles suspended in the solution).

Question 19

What are all monosaccharides?

Answer 19

Reducing sugars.

Question 20

Give two examples of reducing sugars that are disaccharides.

Answer 20

Maltose and lactose.

Question 21

If the concentration of a reducing sugar is higher then what will be happen in respect of the colour change?

Answer 21

It’ll go further.