2. Carbohydrates And Monosaccharides

Question 1

Carbon containing molecules are also known as __________

Answer 1

Organic molecules

Question 2

What is the basic monomer unit in carbohydrates?

Answer 2

A sugar (saccharide)

Question 3

A pair of monosaccharides can be combined to form a __________

Answer 3

Disaccharide

Question 4

Monosaccharides can be combined in much larger numbers to form __________

Answer 4

Polysaccharides

Question 5

Describe a monosaccharide

Answer 5

Sweet tasting
Soluble
General formula (CH2O)n
(n can be any number from 3 to 7)

Question 6

Name three examples of monosaccharides

Answer 6

Glucose
Galactose
Fructose

Question 7

Glucose is a __________ sugar

Answer 7

Hexose (6 carbon)

Question 8

General formula of glucose?

Answer 8

C6H12O6

Question 9

Name the two isomers of glucose

Answer 9

Alpha glucose

Beta glucose

Question 10

Difference between alpha and beta glucose?

Answer 10

The two H’s are at the top and the OH’s are at the bottom in alpha glucose but in beta glucose they’re on opposite sides

Question 11

All monosaccharides and some disaccharides are..?

Answer 11

Reducing sugars

Question 12

Describe reduction

Answer 12

A chemical reaction involving the gain of electrons or hydrogen

Question 13

What is a reducing sugar?

Answer 13

A sugar that can donate electrons to (or reduce) another chemical

Question 14

Name of test for a reducing sugar?

Answer 14

Benedict’s test

Question 15

Benedict’s reagent is..

Answer 15

An alkaline solution 
Of copper(II) sulfate

Question 16

What happens when a reducing sugar is heated with Benedict’s Reagent?

Answer 16

An insoluble red precipitate of copper(I) oxide is formed

Question 17

Benedict’s Test: ?

Answer 17

1) Add food sample to a test tube. Grind up sample in water is sample is not already in liquid form
2) Add an equal volume of Benedict’s reagent
3) Heat the mixture in a gently boiling water bath for five minutes

Question 18

Colour change in Benedict’s test if reducing sugar is present..?

Answer 18

Blue to orange-brown

Question 19

Benedict’s test is a __________ test

Answer 19

Semi quantitative

Question 20

Results of Benedict’s test according to the concentration of reducing sugar present

Answer 20

Blue = none
Green = very low
Yellow = low
Orange = medium
Red = high

Question 21

Large molecules often contain carbon. Explain why this is.

Answer 21

Carbon atoms readily link to one another to form a chain

Question 22

State the general name for a molecule that is made up of many similar repeating units

Answer 22

Polymer

Question 23

Explain why Benedict’s reagent turns red when heated with a reducing sugar

Answer 23

Sugar donates electrons that reduce blue copper(II) sulfate to copper(I) oxide