2.1.2 Biological Molecules – Monosaccharides

Question 1

What is the general formula for a monosaccharide?

Answer 1

Cn(H2O)n

Question 2

Give three properties of monosaccharides

Answer 2

• Made of one sugar molecule
• Dissolve in water (soluble)
• Insoluble in non-polar solvents
• Form crystals (crystalline)
• Form sweet tasting solutions

Question 3

What is the term for a molecule made of two monosaccharides bonded together?

Answer 3

A disaccharide

Question 4

What is the term for a molecule made of many monosaccharides bonded together?

Answer 4

A polysaccharide

Question 5

Draw the structure of alpha glucose

Question 6

Draw the structure of beta glucose

Question 7

What is the difference between alpha and beta glucose?

Answer 7

The positions of the H and OH on carbon 1 are reversed

Question 8

Draw the structure of ribose

Question 9

Name three examples of monosaccharides

Answer 9

1) c3h6o3 - triose
2) c5h10o5 - pentose e.g. DNA and ribose
3) c6h12o6 - hexose e.g. glucose, fructose and galactose

Question 10

What reagent (chemical) used to test reducing sugar?

Answer 10

Benedicts

Question 11

If reducing sugar is present what colour change?

Answer 11

Brick red

Question 12

Why semi-quantitative

Answer 12

Benedicts passes a series of colours before brick red
Each colour indicatres an increasing conc of reducing sugar
Showing a greater colour change