Carbohydrates

Question 1

Elements present in carbohydrates

Answer 1

Carbon, hydrogen, oxygen

Question 2

General formula of carbohydrates

Answer 2

Cx(H2O)y

Question 3

Monosaccharide

Answer 3

a simple sugar molecule eg. glucose, fructose, galactose, ribose

Question 4

Disaccharide

Answer 4

a molecule made up of two monosaccharides joined together by a glycosidic bond eg. lactose, sucrose, maltose

Question 5

Polysaccharide

Answer 5

a polymer made up of many sugar monomers (monosaccharides) eg. glycogen, cellulose, starch

Question 6

Pentose monosaccharides

Answer 6

Sugars which contain 5 Carbon atoms. Two important examples - ribose, the sugar present in RNA nucleotides and deoxyribose, the sugar present in DNA nucleotides

Question 7

Hexose sugar

Answer 7

Sugars which contain 6 Carbon atoms.

Question 8

Which sugar is present in RNA nucleotides?

Answer 8

Ribose, a pentose monosaccharide

Question 9

Which sugar is present in DNA nucleotides?

Answer 9

Deoxyribose, a pentose monosaccharide

Question 10

Triose sugar

Answer 10

Sugars which contain 3 Carbon atoms.

Question 11

The difference between alpha and beta glucose

Answer 11

In alpha glucose, the hydroxyl group is below the plane of the ring, and in beta glucoses it’s above the plane of the ring.

Question 12

How are disaccharides formed?

Answer 12

Condensation reaction takes place. A hydroxyl group and hydrogen form a water molecule which is removed, and a glyosidic bond is formed between the monosaccharide.

Question 13

Example of a triose sugar

Answer 13

triose phosphate - acts as an intermediate in respiration

Question 14

2 Examples of pentose sugars

Answer 14

Ribose - RNA nucleotides

Deoxyribose - DNA nucleotides

Question 15

Example of a hexose sugar

Answer 15

Glucose - used as a respiratory substrate, and in blood sugar

Question 16

3 Polysaccharide examples

Answer 16

Starch
Glycogen
Cellulose

Question 17

4 Monosaccharide examples

Answer 17

Glucose
Fructose
Galactose
Ribose

Question 18

3 Disaccharide examples

Answer 18

Maltose
Sucrose
Lactose

Question 19

Maltose =

Answer 19

glucose + glucose

Question 20

Sucrose =

Answer 20

glucose + fructose

Question 21

Lactose =

Answer 21

glucose + galactose

Question 22

Explain why alpha-glucose links together to form starch whereas beta-glucose links together to form cellulose.

Answer 22

The angle of α 1-4 glycosidic bonds means the glucose chain twists to form a helix. Beta-glucose cannot for coils or branches as one of the glucose molecules is turned upside down so it forms straight chains - cellulose.

Question 23

Important properties of glucose

Answer 23

• glucose is polar so it is soluble as hydrogen bonds form between OH groups and water molecules -> glucose can dissolve in the cytosol of the cell

Question 24

Fructose occurs naturally in…

Answer 24

fruit

Question 25

Sucrose is found in…

Answer 25

cane and table sugar

Question 26

Lactose is found in…

Answer 26

milk and milk products

Question 27

Hydrolysis is …

Answer 27

the breakdown of a molecule into two smaller molecules requiring the addition of a water molecule

Question 28

Condensation is …

Answer 28

a reaction between two molecules resulting in the formation of a larger molecule and the release of a water molecule

Question 29

List the two different polysaccharides that make up starch.

Answer 29

Amylose and amylopectin