AQA A LEVEL BIOLOGY 2020 PAPER 2 MARK SCHEME

Question Marking Guidance Mark Comments

01.1

1. Circular muscle contracts;

2. Radial muscle relaxes;

2

1 and 2. Accept, for

one mark ‘both

muscles contract’ or

‘both muscles relax’

as names of muscles

are in Figure 1.

Reject muscles

constrict.

01.2

1. High (visual) acuity;

2. (Each) cone is connected to a single neurone;

2. (Cones send) separate (sets of) impulses to

brain;

3

2. Accept no retinal

convergence.

2. Accept

‘bipolar/nerve cell’

for neurone.

3. Accept ‘optic nerve’

for brain.

3. Reject ‘signals’,

‘messages’ for

‘impulses’.

3. Accept ‘action

potential’.

01.3

1. Correct answer of 0.6 (%) = 2 marks;;

2. Incorrect answer but shows number sequence

7065 / 7068 / 7069 / (ignore position of

decimal point) = 1 mark

OR

Final answer number sequence has 64 / 65

(ignore preceding zeros, numbers that follow and

position of decimal point) = 1 mark

OR

Final answer is 2.58 / 2.6 (%) = 1 mark

OR

Final answer of 0.43 (%) = 1 mark;

2

1. Ignore any

numbers after 0.6,

2.58, 2.6 and after

0.43.

01.4

1. High (visual) sensitivity;

2. Several rods connected to a single neurone;

3. Enough (neuro)transmitter to reach/overcome

threshold

OR

3

1. Accept retinal

convergence.

2. Accept

‘bipolar/nerve cell’ for

neurone

2. Accept 2, ‘many’ or

MARK SCHEME – A-LEVEL BIOLOGY – 7402/2 – JUNE 2020

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Spatial summation to reach/overcome threshold; more for ‘several’

3. Reject ‘signals’,

‘messages’ for

‘impulses’.

3. Accept named

neurotransmitter.

3. Accept

depolarisation, ‘action

potential’ or ‘generator

potential’ for ‘to reach

threshold’.

3. Generator

potentials combine to

reach threshold/

depolarisation/action

potential/generator

potential.

MARK SCHEME – A-LEVEL BIOLOGY – 7402/2 – JUNE 2020

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Question Marking Guidance Mark Comments

02.1

1. Lipid soluble;

2. (Diffuse through) phospholipid (bilayer);

2

1. Ignore ‘not water

soluble’ or ‘fat soluble’.

1 and 2. Ignore reference

to joining to

receptors/channels/carriers

but reject passage through

protein channels/carriers.

02.2

1. Has a (specific) tertiary structure/shape;

2. (Structures are) complementary;

2

1. Accept in context of AR

or testosterone.

1. Ignore 3D.

2. Reject reference to

antigen.

2. Reject reference to

active site, enzyme,

substrate or induced fit.

02.3

1. (AR is) a transcription factor;

2. Binds to DNA/promoter;

3. (Stimulates) RNA polymerase;

2 max

1. Ignore ‘binds to bases’

or ‘binds to gene’.

1 and 2. Reject reference

to active site, enzyme,

substrate or induced fit.

02.4

1. With 16 or fewer than 16 (repeats the

 association) is significant;

2. With 17 or more than 17 (repeats the

 association) is not significant;

3. With 16 or fewer than 16 (repeats) there is

 less than a 5% or less than 0.05 probability

 of being due to chance

 OR

 With 17 or more than 17 (repeats) there is

 more than a 5% or more than 0.05

 probability of being due to chance

 OR

 Explanation of a probability value e.g. 0.30

 is a 0.30 or 30% probability of being due to

 chance;

4. With 16 or fewer than 16 (repeats) reject the

 null hypothesis

 OR

3 max

If none of the marks is

awarded allow principle

mark of (prostate) cancer

more likely with 16 or less

than 16 (repeats) or

(prostate) cancer less

likely with 17 or more than

17 (repeats)

OR

Alternative principle mark

Correctly links

significant/not significant to

correct probability

value/percentage or to

rejecting/accepting the null

hypothesis.

1. Reject ‘the results are

significant’.

1. Accept ‘difference in

results is significant’.

2, 3 and 4. Accept

reference to any number of

repeats (e.g. 18) between 

MARK SCHEME – A-LEVEL BIOLOGY – 7402/2 – JUNE 2020

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 With 17 or more (repeats) accept the null

 hypothesis;

17 to 20 for 17 or more

than 17 (repeats).

3. Accept equivalent

responses in terms of 95%

or 0.95 probability.

Question Marking Guidance Mark Comments

03.1

1. Stirrer distributes heat (energy);

2. Insulation/space/air reduces loss/gain of heat

OR

Insulation/space/air reduces

conduction/convection;

3. Water has high (specific) heat capacity;

2 max

1. Accept stirrer ensures

equal/even temperature

or prevents build up of

‘hot spots’.

2. Reject vacuum.

03.2

3.28 / 3.3 (kJ g−1

) = 2 marks;;

Incorrect answer but shows 328 / 33 (ignore any

subsequent numbers and decimal point) = 1

mark

OR

Incorrect answer of 6.56 / 6.6 (kJ g−1

) (ignore any

subsequent numbers) = 1 mark;

2

03.3

1. (Light is) reflected;

2. (Light is) wrong wavelength;

3. (Light) misses chlorophyll/

chloroplasts/photosynthetic tissue;

4. CO2 concentration or temperature is a limiting

factor.

2 max

1. Light is not absorbed

on its own is not enough.

2. Accept frequency for

wavelength.

2. Accept reference to

absorbing specified

wavelengths/frequencies.

03.4

1. ATP;

2. Reduced NADP; 2

Accept 1 and 2 in either

order.

2. Reject Reduced NAD.

2. Accept

NADPH/NADPH2.

03.5

Correct answer of 1.31/1.3 × 108

(ignoring any

subsequent numbers after 1.31) = 2 marks;;

Incorrect answer but shows 216 = 1 mark