Carbohydrates

Question 1

what are monosaccharides and give 3 examples?

Answer 1

monomers form which larger molecules form carbohydrates: glucose, galactose and fructose

Question 2

what are disaccharides and how are they formed?

Answer 2

two monosaccharides joined together with a glycosidic bond, formed by a condensation reaction, therefore releasing a molecule of water

Question 3

list 3 disaccharides and the monomers from which they are formed

Answer 3

Maltose = glucose ×2
Lactose = glucose + galactose
Sucrose = glucose + fructose

Question 4

What are polysaccharides and how are they formed

Answer 4

Many monosaccharides joined together with glycosidic bonds formed by a condensation reaction

Question 5

describe the structure of starch

Answer 5

-Made of alpha glucose
Amylose= is lo g and unbranded and forms a coiled shape
Amylopectin= is long and branched due to the 1-6 glycosidic bonds

Question 6

what is the properties of starch?

Answer 6

Amylose- the coiling makes it compact and acts as storage in smaller places
Amylopectin- branches increase the surface are for enzymes to hydrolyse glycosidic bonds allowing glucose to be releases quickly

Question 7

what are the uses for starch?

Answer 7

.plants use starch to store excess glucose as it is too large to leave cells and it is insoluble
.starch can be hydrolysed to release glucose for respiration

Question 8

describe the structure to glycogen

Answer 8

Made of alpha glucose
-is long and branched with side branches with 1-6 glycosidic bonds

Question 9

what are the properties of glycogen?

Answer 9

losts of branches increase the surface area for enzymes to hydrolyse glycosidic bonds allowing a faster release of glucose. It also is a compact molecule and so allows for storage

Question 10

what is the use for glycogen?

Answer 10

Animals store excess glucose as glycogen in muscles and in the liver and is therefore an energy store as it can be hydrolysed to release glucose quickly when needed for respiration

Question 11

describe the structure of cellulose

Answer 11

Made from beta glucose
-long unbranded straight chains with 1-4 glycosidic bonds and the chains are linked together by hydrogen bonds between the glucose molecules which form microfibrills

Question 12

what are the properties of cellulose

Answer 12

the hydrogen bonds between the cellulose chains make the microfibrills strong and flexible allowing them to provide support

Question 13

what are the uses of cellulose?

Answer 13

provides structural support in the cell walls of plants allowing them to become turgid

Question 14

what can polysaccharides be formed from?

Answer 14

glucose monomers that ate joined by 1-4 or 1-6 glycosidic bonds

Question 15

describe the test for reducing sugars

Answer 15

reducing sugars= monosaccharides, maltose and Lactose

1, add benedicts solution to sample
2, heat in a water bath
3, positive result = green, yellow, orange, red precipitate

Question 16

describe the test for non reducing sugars

Answer 16

non reducing sugars = sucrose

1, do benedicts test an stays blue
2, heat in water bath with acid
3, neutralise with an alkaline
4, heat in water bath with benedicts solution
5, positive= green, yellow, orange, red precipitate

Question 17

suggest the method to measure the quantity of sugar in a solution

Answer 17

carry out the benedicts test then filter and dry the precipitate then find the mass