Biological Molecules - Carbohydrates

Question 1

what are the 3 carbohydrate structures

Answer 1

monosaccharides
disaccharides
polysaccharides

Question 2

what is the general formula for monosaccharides

Answer 2

(CH2O)n - n can be any number from 3 to 7

Question 3

name 2 examples of monosaccharides

Answer 3

glucose and fructose

Question 4

which is the chemical test for reducing sugars

Answer 4

benedict’s test

Question 5

name the three steps of benedict’s test for reducing sugars

Answer 5

1. add 2cm^3 of sugar solution into a test tube
2. add 2cm^3 of Benedict’s reagent to the test tube
3. heat (not boil) in a water bath for 5 minutes

Question 6

what colour does a reducing sugar turn when reacted with Benedict’s solution

Answer 6

a reducing sugar will turn BRICK RED when reacted with Benedict’s reagent

Question 7

why does a reducing sugar turn brick red when reacted with Benedict’s reagent

Answer 7

the KETONES of ALDEHYDES present in the reducing sugars DONATES ELECTRONS which REDUCES Benedict’s reagent

Question 8

what is a disaccharide

Answer 8

a disaccharide is two monosaccharides that have been bonded together by a glycosidic bond

Question 9

how is maltose formed

Answer 9

maltose is formed by two glucose molecules bonded together by an alpha 1-4 glycosidic bond

Question 10

how is sucrose formed

Answer 10

sucrose is formed by a glucose molecule and a fructose molecule bonded by an alpha 1-4 glycosidic bond

Question 11

how is lactose formed

Answer 11

lactose is formed by a galactose molecule and a glucose molecule bonded together by a beta 1-4 glycosidic bond

Question 12

how are polymers formed

Answer 12

polymers are formed by condensation reactions

Question 13

what type of bond is present in amylose

Answer 13

amylose is a polysaccharide bonded by an alpha 1-4 glycosidic bond

Question 14

name a structual property of amylose

Answer 14

amylose consists of unbranched chains in a helical structure

Question 15

what makes up starch

Answer 15

starch is made up of a combination of the two polysaccharides amylose and amylopectin

Question 16

what bonds are present in amylopectin

Answer 16

amylopectin is bonded by both alpha 1-4 glycosidic bonds and alpha 1-6 glycosidic bonds

Question 17

name a structural property of amylopectin

Answer 17

amylopectin is a highly branched polysaccharide

Question 18

where is amylose and amylopectin found/stored

Answer 18

amylopectin and amylose are both found/stored in PLASTIDS (in plants). eg) in chloroplasts

Question 19

name two uses of both amylopectin and amylose

Answer 19

1. sources of carbon to help build other molecules that involve carbon
2. starch is produced from glucose during photosynthesis

Question 20

what bonds are present in glycogen

Answer 20

glycogen is bonded together by both alpha 1-4 glycosidic bonds and alpha 1-6 glycosidic bonds

Question 21

name two properties of glycogen

Answer 21

1. higher branched molecule than amylopectin
2. less soluble and more dense than starch as animals are more metabolic than plants so need to break molecules down quicker

Question 22

where is glycogen stored

Answer 22

glycogen is stored in both the liver and muscles

Question 23

name two uses of glycogen

Answer 23

1. glycogen is how animals store carbohydrates (energy)

2. glycogen can be rapidly broken down to be used as energy

Question 24

what bonds are present in cellulose

Answer 24

cellulose is bonded together by beta 1-4 glycosidic bonds and hydrogen bonds

Question 25

name a structural property of cellulose

Answer 25

long chains bonded by beta 1-4 glycosidic bonds with hydrogen bonds between chains to strengthen the polymer

Question 26

where is cellulose found

Answer 26

plant cell walls

Question 27

name two uses of celluose

Answer 27

1. strengthens the cell wall

2. prevents the cell from bursting if it takes in too much water