T1 - 1.2 carbohydrates

Question 1

uses of carbohydrates

Answer 1

• energy source e.g. glucose
• energy storage e.g. glycogen
• constituents of DNA and RNA
• glycolipids and glycoproteins are used in cell membranes for recognition
• cell walls use cellulose

Question 2

what are 2 examples of monosaccharides

Answer 2

alpha glucose, beta glucose

Question 3

what does alpha glucose look like

Answer 3

Question 4

what does beta glucose look like

Answer 4

Question 5

characteristics of monosaccharides

Answer 5

sweet, soluble, can crystallise easily

Question 6

what is a condensation reaction

Answer 6

forms a covalent bond between monomers to form a larger molecule and release water

Question 7

what do condensation reactions form between carbohydrates

Answer 7

glycosidic bonds:
di/polysaccharides

Question 8

what is a hydrolysis reaction

Answer 8

forms smaller molecules by breaking covalent bonds USING WATER

Question 9

how does maltose breakdown

Answer 9

glucose + glucose by maltase

Question 10

how does sucrose breakdown

Answer 10

glucose + fructose by sucrase

Question 11

how does lactose breakdown

Answer 11

glucose + galactose by lactase

Question 12

what is a qualitative test for reducing sugars

Answer 12

• add Benedict’s solution
• heat at 80C for 3 mins
• turns from blue to orange-red precipitate

Question 13

what is a qualitative test for non-reducing sugar

Answer 13

• boil in HCl which hydrolyses the sucrose
• cool and neutralise by adding sodium hydrogen carbonate
• add Benedict’s solution
• heat at 80C for 3 mins
• turns from blue to orange-red precipitate

Question 14

what is a polysaccharide

Answer 14

many monosaccharides joined together with glycosidic bonds

Question 15

what is starch

Answer 15

a polysaccharide found in plants with subunits of alpha glucose

Question 16

what is amylose

Answer 16

straight chain molecules of alpha glucose in starch
made of 1,4 glycosidic bonds

Question 17

what is amylopectin

Answer 17

branched chain molecules of alpha glucose in starch
made of 1,6 glycosidic bonds

Question 18

function of starch

Answer 18

energy storage, insoluble, compact, can be hydrolysed easily

Question 19

what is glycogen

Answer 19

a polysaccharide found in animals that is made of subunits of alpha glucose

Question 20

how does glycogen differ to starch

Answer 20

more branches and more compact in glycogen

Question 21

function of glycogen

Answer 21

stored in muscles and liver for energy storage
smaller chains make it easier to be hydrolysed

Question 22

what is cellulose

Answer 22

a polysaccharide found in plant cell walls made up of subunits of beta glucose

Question 23

what is cellulose made up of

Answer 23

1,4 glucan chain - long and unbranched chains

Question 24

what happens when glucan chains line up parallelly

Answer 24

they form hydrogen bonds between each chain making microfibril (24-36 glucan chains)

Question 25

what happens when microfibril chains line up parallelly

Answer 25

they form hydrogen bonds between them to produce macrofibril

Question 26

what is the benefit of macrofibrils in cell walls

Answer 26

creates a strong and rigid structure which prevents bursting in cell walls

Question 27

how does it benefit starch and glucose to have alpha glucose monomers

Answer 27

provides glucose for respiration rapidly

Question 28

how do the branches benefit starch and glucose

Answer 28

can fit many glucose molecules into a small space

Question 29

are starch and glucose insoluble

Answer 29

yes therefore doesn’t affect the water potential

Question 30

why are glycogen and starch large molecules

Answer 30

cannot cross cell membranes and diffuse