starch, glycogen and cellulose

Question 1

what is the test for starch?

Answer 1

• 2cm cubed of a sample in a test tube
  *add 2 drops of iodine solution to this and sake or stir
• if starch is present the yellow solution will turn blue black

Question 2

where do large amounts of starch occur?

Answer 2

seeds and storage organs

Question 3

what is starch made up of

Answer 3

chains of a-glucose monosaccharides

Question 4

what is the structure of a-glucose?

Answer 4

it has a 6 carbon structure with a chemical formula of C6H12O6

Question 5

what is the main difference between a-glucose and b-glucose?

Answer 5

the orientation of the -OH (hydroxyl) and the -H (hydrogen) groups. OH above the ring on b-glucose and below on a-glucose.

Question 6

why is starch specifically used for energy storage? (5 points)

Answer 6

1. it is insoluble so that it doesn’t affect the water potential as water isn’t drawn into the cells by osmosis
2. it doesn’t diffuse out of cells as it is large and insoluble
3. the unbranched chain is wound into a tight coils so it is compact and a lot can be stored in a small space
4. forms a-glucose when hydrolysed which is easily transported and can be used in respiration
5. the branched chain has many ends where enzymes can act simultaneously so glucose monomers can be released rapidly

Question 7

what do animal cells have instead of starch.

Answer 7

Glycogen

Question 8

what are the main differences between starch and glycogen?

Answer 8

glycogen has shorter chains and it is more highly branched.

Question 9

what type of monomers is cellulose made of?

Answer 9

b-glucose

Question 10

describe the structure of cellulose

Answer 10

it has straight, unbranched chains that run parallel to each other forming hydrogen bonds

Question 11

what is the function of cellulose?

Answer 11

gives rigidity to plant cells and prevents the cell from bursting as water enters