Carbohydrates/Monosaccharide/Disaccharides

Question 1

What are monosaccharides?

Answer 1

Single sugars, monomers of which carbohydrates are made (glucose, galactose and fructose)

Example sentence: Glucose is a common monosaccharide found in fruits.

Question 2

What are disaccharides?

Answer 2

Double sugars, monosaccharide + monosaccharide = Disaccharides (maltose, sucrose and lactose)

Example sentence: Lactose is a disaccharide composed of glucose and galactose.

Question 3

What are polysaccharides?

Answer 3

Compounds that are formed from the combination of hundreds of monosaccharides (starch, glycogen and cellulose)

Example sentence: Starch is a polysaccharide commonly found in plants.

Question 4

What is a carbohydrate?

Answer 4

Compounds containing C,H and O only

Categories of carbohydrate
-monosaccharides
-disaccharides
-polysaccharides

Question 5

What is the general formula of a monosaccharide?

Answer 5

Cn(H2O)n

Question 6

What are the two types of monosaccharides?

Answer 6

Hexose monosaccharides
Pentose monosaccharides

Question 7

What are examples of pentose monosaccharides?

Answer 7

Ribose and Deoxyribose

Ribose is a component of nucleotides of RNA. Deoxyribose is a component of nucleotides of DNA.

Question 8

What are examples of hexose monosaccharides?

Answer 8

Glucose, fructose, and galactose

None

Question 9

What are the components of glucose?

Answer 9

Glucose has a hydroxyl group (-OH) on the carbon atom

None

Question 10

General formula of monosaccharides Cn(H2O)n. Value of n=3…

Answer 10

Trioses—C3(H2O)3—glyceraldehyde

Question 11

General formula of monosaccharides Cn(H2O)n. Value of n= 5…

Answer 11

Pentoses—C5(H2O)5—ribose

Question 12

General formula of monosaccharides Cn(H2O)n. Value of n= 6…

Answer 12

Hexoses—C6(H2O)6—glucose,fructose

Question 13

What is Benedicts test for?

Answer 13

It is a test for reducing sugars

Question 14

What types of carbohydrates are considered reducing sugars?

Answer 14

All monosaccharides + some disaccharides

Question 15

What functional groups do reducing sugars contain?

Answer 15

They contain aldehyde group or ketone group

Question 16

What happens to reducing sugars when heated in an alkaline solution?

Answer 16

They reduce Cu2+ ions to Cu+

Question 17

What are the steps for performing Benedicts test?

Answer 17

Add 2cms of Benedicts solution to test tube using dispenser
Heat in water bath at 80°c for 5 mins
Color change (BLUE, green, yellow, orange, BRICK RED)

Example sentence: After heating the solution, observe the color change to determine the presence of reducing sugars.

Question 18

What is the formula for a disaccharide?

Answer 18

monosaccharide + Monosaccharide = Disaccharide

Question 19

What type of reaction forms a glycosidic bond?

Answer 19

condensation reaction

N/A

Question 20

What are the components of sucrose?

Answer 20

a glucose + fructose = sucrose

N/A

Question 21

What are the components of lactose?

Answer 21

a glucose + galactose = lactose

N/A

Question 22

How are polysaccharides formed?

Answer 22

polysaccharide - formed by many monosaccharides, joined by condensation reaction

N/A

Question 23

What are the components of maltose?

Answer 23

a glucose + a glucose = maltose

N/A

Question 24

How to test for non-reducing sugar?

Answer 24

Add 1cm3 HCI, then heat in 80°C water bath for 5 mins. Remove tube + cool, add 1cm3 NaOH. Then add 2cm3 of benedicts solution to test tube using dispenser. Heat in 80°C water bath for 5 mins.

Question 25

How to test for starch?

Answer 25

Add iodine solution to starch suspension. Turns yellow-orange-black/blue.

Starch forms suspension in water and does not dissolve. Iodine dissolves in potassium iodide solution.

Question 26

What is the effect of heating a non reducing sugar in hydrochloric acid?

Answer 26

This hydrolyses the sugar which then breaks down into monosaccharides