Biological Molecules - 3.1.2.4 Polysaccharides structure and function and the starch test

Question 1

How is the structure of cellulose suited to its function?

Answer 1

• β-Glucose molecules can form long straight chains
• Parallel chains of cellulose form hydrogen bond ‘cross links’ which add strength
• Cellulose is arranged into microfibrils and then fibres, which add yet more strength

Question 2

Which type of bond forms between adjacent α-glucose molecules in glycogen?

Answer 2

α 1-4 glycosidic bonds

Question 3

Unbranched starch (amylose) coils into a…

Answer 3

compact helix structure

Question 4

What test is described below:

Place 2 cm3 of the sample being tested into a test tube

Add 2 drops of iodine solution

A blue black colouration indicates a positive result

Answer 4

The test for starch

Question 5

What form does starch take within plant cells?

Answer 5

Starch grains

Question 6

Which type of bond forms between branching α-glucose molecules in glycogen?

Answer 6

α 1-6 glycosidic bonds

Question 7

Which type of bond forms between unbranched starch (amylose) molecules?

Answer 7

α 1-4 glycosidic bonds

Question 8

How is glycogen different to starch?

Answer 8

Glycogen has many more branches

Question 9

Which type of organism contains starch?

Answer 9

Plants

Question 10

What form does glycogen take in cells?

Answer 10

granules within muscle and liver cells

Question 11

What type of reaction occurs when monosaccharides join?

Answer 11

Condensation reaction

Question 12

How would you test for starch?

Answer 12

1. Place 2 cm3 of the sample being tested into a test tube
2. Add 2 drops of iodine solution
3. A blue black colouration indicates a positive result

Question 13

Cellulose microfibrils are grouped are arranged in parallel groups called…

Answer 13

fibres

Question 14

Which monosaccharide is cellulose made from?

Answer 14

β-Glucose

Question 15

How does the structure of glycogen make it suited to its function?

Answer 15

• It is insoluble so does not cause water to move into the cell via osmosis
• It is large so does not diffuse out of animal cells
• It is compact
• It forms α-Glucose when hydrolysed for respiration
• Many more branches than starch allow α-Glucose to be released faster from glycogen

Question 17

What is the function of glycogen?

Answer 17

an energy store for animal and bacterial cells

Question 18

The coiled helix structure of unbranched starch (amylose) is held in place by…

Answer 18

hydrogen bonds

Question 19

What is the function of cellulose?

Answer 19

• Cellulose is a major component of plant cell walls and provides rigidity to plant cells
• Stops plant cells bursting when water enters

Question 20

How are parallel chains of cellulose held together?

Answer 20

hydrogen bonds

Question 21

What structure does cellulose take?

Answer 21

Long unbranched chains that run parallel to each other

Question 22

Which type of bond forms between branched starch (amylopectin) molecules?

Answer 22

α 1-6 glycosidic bonds

Question 23

Which type of monosaccharide is starch made from?

Answer 23

α-Glucose

Question 24

Which type of bonds join β-Glucose molecules when they form cellulose?

Answer 24

β 1-4 glycosidic bonds

Question 25

Cellulose chains are arranged in parallel groups called….

Answer 25

microfibrils

Question 26

Why does glycogen require more branches than starch?

Answer 26

Animal cells require more energy to function

Question 27

How does the structure of starch make it suited to its function?

Answer 27

• It is insoluble so does not cause water to move into the cell via osmosis
• It is large so does not diffuse out of plant cells
• It is compact
• It forms α-Glucose when hydrolysed for respiration
• Many branches allow α-Glucose to be released fast

Question 28

Name the 3 types of polysaccharide

Answer 28

Starch (amylose and amylopectin)

Glycogen

Cellulose

Question 29

What is the main function of starch?

Answer 29

energy storage in plant cells

Question 30

Describe the structure of glycogen

Answer 30

POLYMER of alpha glucose

joined by glycosidic bonds

branched structure

Question 31

How does glycogen act as a source of energy?

Answer 31

branched chains are HYDROLYSED

into glucose

used in respiration

Question 32

Which type of monosaccharide is glycogen made from?

Answer 32

α-Glucose