AQA AS Biology Paper 2 2021 Marking Scheme

AQA AS Biology Paper 2 2021 Marking Scheme


Question Marking Guidance Mark Comments

01.1 Carboxyl; 1 Accept carboxylic acid

Question Marking Guidance Mark Comments

01.2 Type of R group

1. Unsaturated (fatty acid/hydrocarbon);

Explanation

2. Double bond (between carbons);

2

1. Accept alkene

2. Accept for ‘double bond’,

C=C

Question Marking Guidance Mark Comments

01.3 1. Add ethanol/alcohol then add water and

shake/mix

OR

Add ethanol/alcohol and shake/mix then

pour into/add water;

2. White/milky (emulsion)

OR

(emulsion) test turns white/milky;

2

1. Reject heating the emulsion

test

1. Accept ‘Add Sudan III and

mix’

1. Ignore a second shake

2. Ignore cloudy

2. Reject precipitate

2. Accept (for Sudan III) top

(layer) red

MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2021

6

Question Marking Guidance Mark Comments

01.4 (Similarity)

1. Both have a phospholipid bilayer

OR

Both have fatty acid/hydrophobic tails pointing

in/face each other

OR

 Both have phosphate/polar/hydrophilic heads

pointing out

 OR


 Both have protein;

(Differences)

2. No channel/carrier proteins, whereas fluid

mosaic does

 OR

 Protein layer outside (phospholipids), fluid mosaic

is 'dotted';

3. Cholesterol is not present whereas it is present

in fluid mosaic;

4. Glycoprotein is not present whereas it is present

in fluid mosaic;

5. Glycolipid is not present whereas it is present in

fluid mosaic;

3 max

Accept 2 marks max if

1. is not achieved

2., 3., 4., and 5.

accept first answer

refers to 1935 model

unless otherwise

stated

2. Accept for ‘no

channel/carrier’, no

intrinsic

2. Accept only one

type of protein

whereas fluid

mosaic has many

(types)

TOTAL 8

MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2021

7

Question Marking Guidance Mark Comments

02.1 Mark in pairs: 1 and 2 OR 3 and 4

1. Flattened cells

OR

Single layer of cells;

2. Reduces diffusion distance/pathway;

3. Permeable;

4. Allows diffusion of oxygen/carbon dioxide;

2

1. Reject thin cell

wall/membrane

1. Accept thin cells

1. Accept ‘one cell

thick’

4. Ignore gas

exchange

Question Marking Guidance Mark Comments

02.2 Correct answer for 2 marks = 1.10–1.15;;

Accept for 1 mark,

0.6(1) : 1 (correct FEV1 : FEC ratio)

2

Question Marking Guidance Mark Comments

02.3 1. Less carbon dioxide exhaled/moves out (of lung)

OR

More carbon dioxide remains (in lung);

2. (So) reduced diffusion/concentration gradient

(between blood and alveoli);

3. Less/slower movement of carbon dioxide out of

blood

OR

More carbon dioxide stays in blood;


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Category AQA Questions and Marking Scheme
Authors Qwivy.com
Pages 18
Language English
Tags AQA AS Biology Paper 2 2021 Marking Scheme
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