AQA A Level Biology 2021 Paper 1 Mark Scheme

AQA A Level Biology 2021 Paper 1 Mark Scheme


Question Marking Guidance Mark Comments

01.1 1. Substrate binds to the active site/enzyme

OR

Enzyme-substrate complex forms;

2. Active site changes shape (slightly) so it is

complementary to substrate

OR

Active site changes shape (slightly) so

distorting/breaking/forming bonds in the

substrate;

3. Reduces activation energy;

3

1. Accept for ‘binds’,

fits

Question Marking Guidance Mark Comments

01.2 Adenosine diphosphate; 1

Question Marking Guidance Mark Comments

01.3 Mark in pairs, 1 and 2 OR 3 and 4 OR 5 and 6

1. Boil

OR

Add (strong) acid/alkali;

2. Denatures the enzyme/ATP synthase;

 OR

3. Put in ice/fridge/freezer;

4. Lower kinetic energy so no enzyme-substrate

complexes form;

 OR

5. Add high concentration of inhibitor;

6. Enzyme-substrate complexes do not form;

2

1. Accept heat at >

50oC OR at very

high temperatures

2. Accept for

'denatures', a

description of

denaturation

4. Accept ES for

enzyme substrate

complex

MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2021

6

Question Marking Guidance Mark Comments

01.4 1. (With) increasing Pi concentration, more

enzyme-substrate complexes are formed;

2. At or above 40 (mmol dm-3

) all active sites

occupied

OR

 At or above 40 (mmol dm-3

) enzyme

concentration is a limiting factor;

2

MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2021

7

Question Marking Guidance Mark Comments

02.1 1. Large(r) organisms have a small(er) surface

area:volume (ratio);

 OR

Small(er) organisms have a large(r) surface

area:volume (ratio);

2. Overcomes long diffusion pathway

OR

Faster diffusion;

2

2.Accept short

diffusion pathway

2. Accept for ‘faster’,

more

Question Marking Guidance Mark Comments

02.2 Mark in pairs, 1, and 2 OR 3. and 4.

1. Water has low(er) oxygen partial

pressure/concentration (than air);

2. So (system on outside) gives large surface area

(in contact with water)

 OR

 So (system on outside) reduces diffusion

distance (between water and blood);

3. Water is dense(r) (than air);

4. (So) water supports the systems/gills;

No comments found.
Login to post a comment
This item has not received any review yet.
Login to review this item
No Questions / Answers added yet.
Category AQA Questions and Marking Scheme
Authors Qwivy.com
Pages 22
Language English
Tags AQA A Level Biology 2021 Paper 1 Mark Scheme
Comments 0
Sales 0
Similar items
cover
Qwivy.com 26 pages English
$15.00
cover
Qwivy.com 26 pages English
$15.00
cover
Qwivy.com 46 pages English
AQA Food GCSE Mark Schemes | June 2023 AQA Questions and Marking Scheme
$30.00
cover
Qwivy.com 12 pages English
$18.88
Recently viewed items

We use cookies to understand how you use our website and to improve your experience. This includes personalizing content and advertising. To learn more, please click Here. By continuing to use our website, you accept our use of cookies, Privacy policy and terms & conditions.

Processing