AS PAPER 1 2019

Question 1

Describe the role of antibodies in producing a positive result in an ELISA test. [4 marks]

Answer 1

first antibody binds to antigen
second antibody with enzyme attached is added
second antibody attaches to antigen
substrate is added and colour changes

Question 2

Explain why it is more useful to calculate and index of diversity than to record species richness. [2 marks]

Answer 2

index of diversity also measures size of each species
this is useful because there may be many of some species

Question 3

Describe 3 properties of this solution and explain how each property prevented damage to the organelles. [3 marks]

Answer 3

ice cold prevents enzyme activity
buffered prevents denaturing of enzyme
isotonic to prevent bursting of organelle

Question 4

What can you conclude about the adaptation of the gas exchange surfaces of these species of fish?

Answer 4

the lower the oxygen concentration, the higher ratio of gill surface area to body mass
supplies enough oxygen for respiration

Question 5

Explain how the active site of an enzyme causes a high rate of reaction. [3 marks]

Answer 5

lowers activation energy
induced fit causes active site to change shape
E-S complex causes bonds to break