polysaccharides

Question 1

what are polysaccharides?

Answer 1

carbohydrates

Question 2

what is the bond called between monosaccharides?

Answer 2

glycosidic

Question 3

how are polysaccharides broken down? what are they broken down into?

Answer 3

hydrolysis, monosaccharides

Question 4

what is amylose broken down into?

Answer 4

alpha glucose molecules

Question 5

how are polysaccharides formed?

Answer 5

through the condensation of many glucose units

Question 6

how do cells get energy?

Answer 6

from glucose

Question 7

how do plants store excess glucose?

Answer 7

store it as starch which is broken down into glucose when needed

Question 8

what is starch?

Answer 8

a polysaccharide found in plants

Question 9

what is starch made from?

Answer 9

long chains of alpha glucose

Question 10

how can starch be stored in small spaces?

Answer 10

it coils very tightly so is compact

Question 11

is starch soluble? what does this mean for the cell?

Answer 11

no, its insoluble so it doesn’t affect the osmotic balance/water potential of the cell

Question 12

why can’t starch leave the cell?

Answer 12

because its a long molecule made of many glucose units, its too big

Question 13

what is amylose? what is its structure?

Answer 13

an unbranched version of starch that only consists of alpha 1,4 links. The angles of the glycosidic bonds give it a coiled structure. A lot can fit into a small space and it is compact.

Question 14

what is amylopectin? what is its structure?

Answer 14

A branched form of starch which consists of alpha glucose 1,4 links with branches formed by 1,6 links. The side chains allow the enzymes that break down the molecule to get to the bonds easily. The are a good source of quick glucose.

Question 15

what is the test for starch?

Answer 15

Add iodine in potassium iodide solution and if sample goes from brown/orange to blue/black starch is present.

Question 16

what is glycogen and where is it found?

Answer 16

a polysaccharide found in animals as small granules mainly found in muscles and the liver

Question 17

what is glycogen useful for?

Answer 17

useful as an energy storage molecule as its easily hydrolysed back to glucose and is compact. Lots of branches means that stored glucose can be released quickly

Question 18

describe the structure of glycogen

Answer 18

formed from short chains of alpha glucose and is branched

Question 19

what is cellulose made from?

Answer 19

long unbranched chains of beta glucose

Question 20

what happens when a glycosidic bond forms in cellulose?

Answer 20

the molecule rotates 180º to the next to form a zig zag. The OH on carbon 1 is inverted

Question 21

describe the structure of cellulose

Answer 21

the beta chains line up and hydrogen bonds form crosslinks. The hydrogen bonds by themselves are quite weak but together they are strong

Question 22

what do cellulose chains form? what do they do?

Answer 22

microfibrils which lie parallel to form fibres. They are strong fibres which provide structural support

Question 23

what is cellulose used for?

Answer 23

used in cell walls to provide rigidity. It applies inward pressure to withstand the pressure to stop the cell from bursting. This is when the plant is turgid.

Question 24

Is starch soluble or insoluble? Why is this a benefit?

Answer 24

It is insoluble in water so doesn’t affect water potential. Therefore, it doesn’t cause water to enter the cell by osmosis which would make them swell

Question 25

What is the main storage material in animals?

Answer 25

Glycogen

Question 26

What is the main energy storage material in plants?

Answer 26

Starch

Question 27

Why is glycogen a good storage molecule?

Answer 27

It is compact