Carbohydrates

Question 1

Three elements that all carbohydrates are made of

Answer 1

Carbon, oxygen and hydrogen

Question 2

Uses of carbohydrates

Answer 2

Used as energy sources and structural materials in organisms

Question 3

Three main groups of carbohydrates and brief description

Answer 3

-monosaccharides(simple sugars)
-disaccharides(two monosaccharides)
-polysaccharides(large molecules formed from many monosaccharides)

Question 4

Three types of monosaccharides

Answer 4

-glucose(alpha and beta)
-fructose
-galactose

Question 5

Basic structure of monosaccharides

Answer 5

-contain C double bonded to O(carbonyl group) and at least two OH(hydroxyl groups) which take part in reactions

Question 6

Structure of glucose

Answer 6

Contains 6 carbon atoms arranged in hexagon so is a hexose sugar
-C6H12O6
-highly soluble and is main form in which carbohydrates are transported around body
-exist as two structural isomers: alpha and beta

Question 7

Difference between glucose’s two structural isomers

Answer 7

-alpha glucose has OH group attached below carbon 1
-beta glucose has OH group attached above carbon 1
This minor structural difference has major effect on biological roles as determines which bonds can be formed

Question 8

Fructose properties

Answer 8

Very soluble and is main sugar in fruit
-pentose sugar

Question 9

Galactose properties

Answer 9

Not as soluble as glucose but important in production of glycolipids and glycoproteins

Question 10

Why are all monosaccharides reducing sugars

Answer 10

As they can donate electrons to other chemicals

Question 11

How are disaccharides such as maltose formed

Answer 11

Condensation reaction between hydroxyl group on both alpha glucose to form 1-4 glycosidic bond and produce water

Question 12

How can disaccharides be broken apart

Answer 12

Can be broken apart in a hydrolysis reaction requiring a molecule of water

Question 13

What do alpha glucose monomers condense to form

Answer 13

Condense to form starch and glycogen

Question 14

What do beta glucose molecules condense to form

Answer 14

Polymers of cellulose

Question 15

What two polysaccharides does starch consist of

Answer 15

Amylose and amylopectin

Question 16

Amylose properties

Answer 16

Unbranched polysaccharide made up of alpha glucose molecules joined together in a series of condensation reactions with 1-4 glycosidic bonds between them. It is unbranched so can coil up into helix held together by hydrogen bonds between hydroxyl groups on molecules

Question 17

Amylopectin properties

Answer 17

Polysaccharide of alpha glucose molecules joined by 1-4 glycosidic bonds, branched every 15-20 molecules with chains joined by 1-6 glycosidic bonds.

Question 18

Advantage of amylopectin being branched

Answer 18

As it is branched it has many ends for enzymes to break down the polysaccharide simultaneously and release glucose for respiration

Question 19

Properties of starch and why these are important

Answer 19

-insoluble in water meaning it does not affect water potential so water is not drawn into cells by osmosis
-too large to pass across cell membrane
-compact so a lot can be stored in a small space
-when hydrolysed it forms alpha glucose which is easily transported for use in respiration

Question 20

Glycogen properties

Answer 20

-similar structure to starch but has shorter chains and more highly branched due to more 1-6 glycosidic bonds along with 1-4 glycosidic bonds
-shorter chains means more branched ends for enzymes to work simultaneously to release glucose and as this is found in animal cells means can keep up with metabolic demand
-stored as small granules mainly in muscles and liver

Question 21

what type of glucose is glycogen made up of

Answer 21

Alpha glucose

Question 22

Monosaccharides maltose is made of

Answer 22

Two alpha glucose

Question 23

Monosaccharides sucrose is made of

Answer 23

Fructose and glucose

Question 24

Monosaccharides lactose is made of

Answer 24

Galactose and glucose