Carbohydrates

Question 1

Elemental composition of carbohydrates

Answer 1

Carbon
Hydrogen
Oxygen

Question 2

General formula for carbohydrates

Answer 2

Cm(H20)n

Question 3

Monosaccharides

Answer 3

Monomers for carbohydrates

Question 4

Simplest monosaccharide formula

Answer 4

(CH2O)n

Question 5

Triose sugar

Answer 5

Lactic acid

Question 6

Pentose sugar

Answer 6

Ribose

Question 7

Hexose sugar

Answer 7

Glucose

Fructose

Question 8

Properties of monosaccharides

Answer 8

Soluble, sweet

Question 9

Structure of alpha glucose

Answer 9

C3, OH on top

Question 10

Structure of beta glucose

Answer 10

C1, OH and H flipped

Question 11

Glycosidic bonding

Answer 11

H and OH bond to form a bond with just oxygen

Release water, condensation reaction

Question 12

Formation of maltose

Answer 12

Glucose and glucose

Question 13

Formation sucrose

Answer 13

Glucose and fructose

Question 14

Formation of lactose

Answer 14

Glucose and galactose

Question 15

Properties of starch

Answer 15

Storage molecule in plants
Insoluble
Easily broken down, built up
Small granules
Food reserve formed when excess glucose formed from photosynthesis
Fuel for respiration and gernimation
Indirect food source for animals

Question 16

Structure of starch

Answer 16

Alpha glucose polymer

Mixture of amylose and amylopectin

Question 17

Amylose

Answer 17

Unbranched molecule
300 glucose units
1, 4 bond
Helical chain

Question 18

Amylopectin

Answer 18

Branched chain
1300-1500 glucose units/molecules
1, 4, 1, 6 bonds

Question 19

Structure related to function in starch

Answer 19

Large, insoluble
Highly branched, quick to break down
Folds easily, compact

Question 20

Glycogen properties

Answer 20

Found in animal muscle and liver
Insoluble, compact, easily broken down
Granules in animals and fungi
Alpha glucose polymer
1, 4, 1, 6 glycosidic bonds
Smaller chains, 10-20 glucose units

Question 21

Glycogen structure related to function

Answer 21

Highly branched, short chain nature, quickly converted into glucose, needed immediately in respiration
Large insoluble molecule, no effect on osmosis
Size ensures that enough is stored

Question 22

Cellulose properties

Answer 22

Beta glucose polymer
Long unbranched chain 10000 monomers
1, 4 glycosidic 180 rotation
Hydrogen bonds formed between parallel chains for structural stability

Question 23

Structure related to function

Answer 23

Cross linking between chains, stability
Structural support to cell walls
Cotton in fabric, rayon, cellophane
Hard to digest

Question 24

Test for reducing sugars explanations

Answer 24

Monosaccharides gain electrons from Benedict’s reagent. (Solution of copper II sulphate)
Red precipitate copper I oxide formed when heated

Question 25

Test for reducing sugars

Answer 25

Form solution of sample
Add equal volume of Benedict’s solution
Heat in hot water bath
Shows you relative amounts of monosaccharide present, semi quantitative test nature

Question 26

Test for non reducing sugars

Answer 26

Non reducing as they do not change colour of Benedict’s reagent
Break down into monosaccharide by hydrolysis
Add dilute hydrochloride acid to hydrolyse disachs into monosaccs
Add NaHCO3 to neutralise acid
Test pH for alkaline solution
Reducing sugar test