Polysaccharides

Question 1

Name the type of monomer that makes up polysaccharides.

Answer 1

Monosaccharides

Question 2

What is the main energy storage in:
a) plants
b) animals

Answer 2

a) starch
b) glycogen

Question 3

Is starch soluble or insoluble?

Answer 3

insoluble

Question 4

Describe why starch being insoluble makes it good for storage.

Answer 4

Because it’s insoluble it doesn’t affect water potential so it causes water to enter cells by osmosis, which makes them swell

Question 5

Explain an advantage why amylopectin is suitable for energy storage

Answer 5

It has a lot of side branches, which makes the enzymes that break amylopectin down can get to the glycosidic bonds easily. This means glucose can be released quickly when it’s needed

Question 6

Which polysaccharide is the major component of plant cell walls?

Answer 6

Cellulose

Question 7

Describe the structure of cellulose and explain how its structure makes it suited to its function in cell walls

Answer 7

Cellulose is made from long, unbranched chains of beta glucose. These are joined by hydrogen bonds to form microfibrils. Microfibrils are very strong which means they provide support/strength/rigidity in the cell wall.

Question 8

Describe the method you would use to test for the presence of starch and say what a positive and negative result would look like.

Answer 8

Use the iodine test- add iodine dissolved in potassium iodide solution to test a sample. Look at the colour of the sample for the result. A positive result would be dark blue-black and a negative result would be a browny-orange colour.