1.4: Starch, Glycogen and Cellulose

Question 1

What are the 3 polymers of glucose

Answer 1

Starch - Plant storage

Glycogen - Animal storage

Cellulose - Cell walls (protection in plants)

Question 2

What is starch made of

Answer 2

Alpha glucose monosaccharides linked by glycosidic bonds formed during condensation reactions

Question 3

What is the role of starch

Answer 3

Energy storage

Question 4

How is starch suited to its role (5)

Answer 4

1. Insoluble so doesnt affect water potential
2. Large, doesnt diffuse out of cells
3. Compact - lots of energy in a small space
4. When hydrolysed it forms alpha glucose - this is easily transported and readily used in respiration
5. The branched form has many ends which can all be acted on by enzymes simultaneously, leading to rapid release of alpha glucose

Question 5

What is glycogen made of

Answer 5

Alpha glucose

Question 6

Where is glycogen found

Answer 6

in animals AND BACTERIA

Question 7

Difference between glycogen and starch

Answer 7

Glycogen has shorter chains, but is more highly branched

Question 8

Where is glycogen usually found

Answer 8

As small granules in the muscles and the liver

Question 9

Why is its presence usually small

Answer 9

Because fat is the main storage molecule in animals

Question 10

Why does the structure of glycogen suit its function (4)

Answer 10

1. It is insoluble and therefore does not affect water potential
2. Insoluble so doesnt diffuse out of cells
3. Compact, so a lot can be stored in a small space
4. More highly branched than starch so many enzymes can act at once to simultaneously release glucose monomers

Question 11

What is cellulose made of

Answer 11

Beta glucose

Question 12

What shape does cellulose form

Answer 12

Straight, unbranched chains that run parallel which allows hydrogen bonds to form cross linkages

Question 13

What are cellulose molecules grouped together to form

Answer 13

Microfibrils, which are arranged into fibres

Question 14

Where is cellulose found

Answer 14

In plant cell walls to provide rigidity to the cell

Question 15

How is the structure of cellulose suited to its function of providing support (3)

Answer 15

1. Made of Beta glucose so form long, straight, unbranched chains
2. These cellulose chains run parallel to each other and are cross linked by hydrogen bonds which adds collective strength
3. The molecules are are grouped to form microfibrils which in turn are grouped to form fibres, all of which providing more strength