monomers and polymers exam paper

Question 1

The emulsion test tests for the presence of lipids, describe the steps involved:

Answer 1

1) Place food sample in ethanol, shake well and leave to sit for 3 - 5 mins
2) Pour solution in distilled water and observe colour
(milky white emulsion means lipid is present)

Question 2

Describe the composition of a phospholipid:

Answer 2

one phosphate head, a glycerole molecule and 2 fatty acid tails.

Question 3

Why is it an advantage to have a high amount of cholesterol in red blood cells?

Answer 3

Cholesterol helps to maintain shape of red blood cells

Question 4

Name 2 differences between starch and cellulose:

Answer 4

Starch is made of alpha glucose molecules but cellulose is made of Beta glucose molecules

Question 5

Starch is found in plant cells?

Answer 5

True

Question 6

Starch contains Beta glucose molecules?

Answer 6

False

Starch contains alpha-glucose molecules

Question 7

Starch contains glycosidic bonds?

Answer 7

True

Question 8

Cellulose is found in plant cells?

Answer 8

True

Question 9

Cellulose contains glycosidic bonds?

Answer 9

True

Question 10

Cellulose contains Beta glucose molecules?

Answer 10

True

Question 11

Glycogen is found in plant cells?

Answer 11

False

Glycogen is found in animal cells

Question 12

Glycogen contains glycosidic bonds?

Answer 12

True

Question 13

Glycogen contains Beta glucose molecules?

Answer 13

false

glycogen contains alpha-glucose molecules

Question 14

Starch, cellulose and glycogen are all carbohydrates?

Answer 14

true

Question 15

What type of reaction would breakdown the following carbohydrates: starch, cellulose and glycogen?

Answer 15

hydrolysis

Question 16

What features of starch enables it to act as a storage substance?

Answer 16

• coiled into a double helix, so that it’s compact and more can be stored
• insoluble, this means water potential isn’t affected via osmosis and so more can be stored

Question 17

What monomer forms a cellulose molecules?

Answer 17

Beta-glucose

Question 18

give two ways starch and cellulose are structurally different?

Answer 18

• Starch is formed from alpha-glucose
• cellulose is formed from beta-glucose
• starch is coiled into a double helix
• cellulose is a long straight chain

Question 19

What is the function of cellulose?

Answer 19

Cellulose’s function is to keep the structure of plant cell walls turgid and stable

Question 20

How is the structure if cellulose linked to its function?

Answer 20

the hyrdogen bonds that link the molecules strengthens the structure, this enables cellulose to keep the cell wall turgid

Question 21

How do we know DNA is a polymer?

Answer 21

made of repeating units

Question 22

How do enzyme inhibitors prevent substrates molecules from being converted?

Answer 22

• binds to active site, prevents substrate from binding and so enzyme substrate complex doesn’t form

Question 23

What type of reaction is sped up by the enzyme lactase?

Answer 23

hyrdolysis

Question 24

Lactose + water produces…?

Answer 24

galacatose + glucose

Question 25

How would you use a biochemical test to show the presence of reducing sugars?

Answer 25

1) Add a heated benedicts reagent to sample

2) If solution turns orange, yellow or red a reducing sugar is present

Question 26

What is lactose made of ?

Answer 26

glucose + galactose

Question 27

Why is there a higher concentration of reducing sugars when lactose is broken down?

Answer 27

two sugars are produced

Question 28

Why does a high conc of galactose slow down the breakdown of lactose by lactase?

Answer 28

Galactose is a competitive inhibitor of lactose because they have similar shapes
This means it able to bind to the active site
This prevents prevents lactose form binding because the active sites are occupied - which also means less enzyme substrate

Question 29

How are hydrolysis and condensation important for the formation of new adult proteins?

Answer 29

hydrolysis breaks down protein + produces amino acids

protein synthesis requires condensation reaction

Question 30

What is an unsaturated fatty acid?

Answer 30

A fatty acid with double bonds between the carbon molecules

Question 31

What equation shows the reaction catalysed by lactase?

Answer 31

lactose + water –> glucose + galactose

Question 32

What chemical reaction is shown in this reaction:

lactose + water –> glucose + galactose

Answer 32

hydrolysis

Question 33

Name 3 disaccharides:

Answer 33

sucrose, maltose and lactose

Question 34

What would be the products of a hydrolysed sucrose?

Answer 34

glucose and fructose

Question 35

What is a polymer?

Answer 35

Polymers are molucules made of long, repeating units (monomers).

Question 36

Name 3 biologically important polymers?

Answer 36

starch, proteins and cellulose

Question 37

Why are buffer solutions added to mixtures?

Answer 37

To keep PH constant - so enzymes aren’t denatured