Polysaccharides

Question 1

What monosaccharide is the polysaccharide glycogen made of?

Answer 1

Alpha glucose

Question 2

What monosaccharide is the polysaccharide starch made of?

Answer 2

Alpha glucose

Question 3

What monosaccharide is the polysaccharide cellulose made of?

Answer 3

Beta glucose

Question 4

What is the role of starch?

Answer 4

Energy store in plants

Question 5

What is the role of glycogen?

Answer 5

Major carbohydrate storage product in animals
Help regulate blood glucose sugar levels

Question 6

What is the role of cellulose?

Answer 6

Provide rigidity to the plant cell→strength in cell walls

Question 7

What causes the molecules to form branches in starch?

Answer 7

1,6 glycosidic bonds

Question 8

Why is starch being insoluble important?

Answer 8

• No osmotic effect - does not affect water potential
• does not leave cell

Question 9

Why is it important for starch to have a compact structure?

Answer 9

Coiled/helical/spiral so a lot can be packed in a small space

Question 10

Why is starch being in a long/large chain helpful to its function?

Answer 10

So the starch does not leave cell

Question 11

Why is it important that starch has a branched chain?

Answer 11

Gives many ends for enzymes to hydrolyse/remove glucose quickly for respiration

Question 12

How do you test for the presence of starch?

Answer 12

• Add iodine
• look for blue/black colour

Question 13

How can we measure the actual size of starch grains drawn in a diagram from a microscope?

Answer 13

The actual size ( um ) = image ( mm ) divided by magnification (x)

Question 14

How does the structure of glycogen differ from that of starch if they are both made of alpha glucose?

Answer 14

It has more 1,6 branches

Question 15

What is the difference in the roles of glycogen and starch?

Answer 15

Glycogen stores glucose in animals whereas starch stores glucose in plants

Question 16

What is the name of an OH group?

Answer 16

Hydroxyl

Question 17

What must happen to enable the OH groups of the beta glucose to get close enough to react to make a glycosidic bond?

Answer 17

Alternative glucose molecules are rotated 180°

Question 18

What cellular structure is made out of cellulose?

Answer 18

Plant cell walls

Question 19

How do microfibrils form?

Answer 19

Many hydrogen bonds between OH groups on different parallel cellulose molecules form cross links between adjacent chains, forming micofiblis

Question 20

The beta 1,4 bond is difficult to break and so resists digestion by enzymes, so how do herbivores such as cows manage to digest grass?

Answer 20

• Only bacteria make cellulase, the enzyme needed to digest cellulose
• Bacteria live in the digestive systems of herbivores