Polysaccharides

Question 1

What is starch made from?

Answer 1

Many alpha glucose molecules

Question 2

What is the biological importance of starch?

Answer 2

It is a carbohydrate storage in plants

Question 3

What is glycogen made of?

Answer 3

Many alpha glucose molecules

Question 4

What is the biological importance of glycogen?

Answer 4

It is a carbohydrate storage in animals

Question 5

What is cellulose made from?

Answer 5

Many beta glucose molecules

Question 6

What is the biological importance of cellulose?

Answer 6

It is in plant cell walls

Question 7

What are the two polymers within starch?

Answer 7

Long, straight chains of amylose and branched chains of amylopectin

Question 8

What is amylose made of?

Answer 8

Many alpha glucose molecules with glycosidic bonds between carbon 1 on one molecule and carbon 2 on another, forming an alpha 1,4 glycosidic bond

Question 9

How does amylose coil up?

Answer 9

Into a helix due to the angle of the glycosidic bond and the structure is held together by hydrogen bonds

Question 10

Why does iodine solution turn blue-black in starch?

Answer 10

The amylose coils trap iodine molecules, turning it blue black and this can be reversed by unraveling the coil by heating to break the hydrogen bonds

Question 11

What is the structure of amylopectin?

Answer 11

It has many alpha 1,4 glycosidic bonds and alpha 1,6 glycosidic bonds to form branches, which occur every 25 glucose molecules

Question 12

What is the structure of glycogen?

Answer 12

It has shorter alpha 1,4 linked glucose chains than amylopectin and many more alpha 1,6 glycosidic bonds so many more branches

Question 13

Why is glycogen more compact?

Answer 13

So less space is needed than in plants as animals are mobile

Question 14

What is the solubility of glycogen and starch?

Answer 14

They are both insoluble

Question 15

Why are starch and glycogen insoluble?

Answer 15

So the water potential is not affected as if there is too much water in a cell, it will burst.

Question 16

What is water potential?

Answer 16

Water will move from where it is less negative (pure, more concentrated) to where it is more negative (lower water concentration)

Question 17

Why are both starch and glycogen held in branched chains?

Answer 17

So that many molecules of glucose can be readily broken off the ends of the branches and released

Question 18

How does energy come from glucose?

Answer 18

Glucose molecules have lots of bonds which can be broken down by enzymes to release enough chemical energy to synthesise ATP

Question 19

What is ATP?

Answer 19

Adenosine Tri-phosphate, made during respiration and is a molecule that holds small amounts of energy that can be readily released for cellular reactions.

Question 20

Why do simple sugars release energy easily?

Answer 20

They are small simple molecules used for energy supply

Question 21

What are complex carbohydrates used for?

Answer 21

They are more stable, compact and mostly insoluble so hey can be broken down when needed but are less ready stores of energy so are mainly used for energy storage

Question 22

What does cellulose makes?

Answer 22

Fibres which are very stable and strong which is ideal for structural support in plant cell walls.

Question 23

How is the bond between cellulose monomers drawn?

Answer 23

It is drawn twisted with a zigzag line

Question 24

Where is cellulose found?

Answer 24

Only in plant cell walls

Question 25

What does cellulose form?

Answer 25

Long straight chains which are stronger than amylose

Question 26

How do hydrogen bonds form within cellulose?

Answer 26

Cellulose monomers contain many OH groups on the outside an then 60-70 cellulose molecules in chains which become cross linked by hydrogen bonds to form microfibrils

Question 27

How are macrofibrils formed?

Answer 27

By microfibrils which are held together by more hydrogen bonds