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Cambridge International AS & A Level

BIOLOGY 9700/53
Paper 5 Planning, Analysis and Evaluation May/June 2024
MARK SCHEME
Maximum Mark: 30

Published

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.

Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.

Cambridge International will not enter into discussions about these mark schemes.

Cambridge International is publishing the mark schemes for the May/June 2024 series for most
Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some
Cambridge O Level components.

This document consists of 11 printed pages.

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Generic Marking Principles

These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the
specific content of the mark scheme or generic level descriptions for a question. Each question paper and mark scheme will also comply with these
marking principles.

GENERIC MARKING PRINCIPLE 1:

Marks must be awarded in line with:

 the specific content of the mark scheme or the generic level descriptors for the question
 the specific skills defined in the mark scheme or in the generic level descriptors for the question
 the standard of response required by a candidate as exemplified by the standardisation scripts.

GENERIC MARKING PRINCIPLE 2:

Marks awarded are always whole marks (not half marks, or other fractions).

GENERIC MARKING PRINCIPLE 3:

Marks must be awarded positively:

 marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond
the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate
 marks are awarded when candidates clearly demonstrate what they know and can do
 marks are not deducted for errors
 marks are not deducted for omissions
 answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the
question as indicated by the mark scheme. The meaning, however, should be unambiguous.

GENERIC MARKING PRINCIPLE 4:

Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level
descriptors.

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GENERIC MARKING PRINCIPLE 5:

Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may
be limited according to the quality of the candidate responses seen).

GENERIC MARKING PRINCIPLE 6:

Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or
grade descriptors in mind.

Science-Specific Marking Principles

1 Examiners should consider the context and scientific use of any keywords when awarding marks. Although keywords may be present, marks
should not be awarded if the keywords are used incorrectly.

2 The examiner should not choose between contradictory statements given in the same question part, and credit should not be awarded for
any correct statement that is contradicted within the same question part. Wrong science that is irrelevant to the question should be ignored.

3 Although spellings do not have to be correct, spellings of syllabus terms must allow for clear and unambiguous separation from other
syllabus terms with which they may be confused (e.g. ethane / ethene, glucagon / glycogen, refraction / reflection).

4 The error carried forward (ecf) principle should be applied, where appropriate. If an incorrect answer is subsequently used in a scientifically
correct way, the candidate should be awarded these subsequent marking points. Further guidance will be included in the mark scheme
where necessary and any exceptions to this general principle will be noted.

5 ‘List rule’ guidance

For questions that require n responses (e.g. State two reasons …):

 The response should be read as continuous prose, even when numbered answer spaces are provided.
 Any response marked ignore in the mark scheme should not count towards n.
 Incorrect responses should not be awarded credit but will still count towards n.
 Read the entire response to check for any responses that contradict those that would otherwise be credited. Credit should not be
awarded for any responses that are contradicted within the rest of the response. Where two responses contradict one another, this
should be treated as a single incorrect response.
 Non-contradictory responses after the first n responses may be ignored even if they include incorrect science.

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6 Calculation specific guidance

Correct answers to calculations should be given full credit even if there is no working or incorrect working, unless the question states ‘show
your working’.

For questions in which the number of significant figures required is not stated, credit should be awarded for correct answers when rounded
by the examiner to the number of significant figures given in the mark scheme. This may not apply to measured values.

For answers given in standard form (e.g. a  10n) in which the convention of restricting the value of the coefficient (a) to a value between 1
and 10 is not followed, credit may still be awarded if the answer can be converted to the answer given in the mark scheme.

Unless a separate mark is given for a unit, a missing or incorrect unit will normally mean that the final calculation mark is not awarded.
Exceptions to this general principle will be noted in the mark scheme.

7 Guidance for chemical equations

Multiples / fractions of coefficients used in chemical equations are acceptable unless stated otherwise in the mark scheme.

State symbols given in an equation should be ignored unless asked for in the question or stated otherwise in the mark scheme.

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Mark scheme abbreviations:

; separates marking points

/ alternative answers for the same point
A accept (for answers correctly cued by the question, or by extra guidance)
R reject
I ignore
() the word / phrase in brackets is not required, but sets the context
AW alternative wording (where responses vary more than usual)
underline actual word given must be used by candidate (grammatical variants accepted)
max indicates the maximum number of marks that can be given
ora or reverse argument
mp marking point (with relevant number)
ecf error carried forward
AVP alternative valid point

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Question Answer Marks

1(a)(i) independent variable 1

type of blood vessel / artery and vein
and
dependent variable
mass required to break (the blood vessel) ;

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Question Answer Marks

1(a)(ii) any six from: 6

1 method to cut the blood vessel ;

2 method to measure blood vessel of, same / stated, length / AW ;

3 idea of discard samples that are damaged ;

4 idea of waiting (to see if the blood vessel breaks) before adding the next (10 g) mass ;

5 use, artery and vein / blood vessels, from the same source ;

6 add (10 g) masses, to the mass hanger, until the blood vessel breaks ;

7 idea of measuring mass of mass hanger / including mass of mass hanger ;

8 for each type of blood vessel, measure / note / record / AW, (total) mass when the blood vessel broke ;

9 use at least three measurements for each type of blood vessel and calculate a mean ;

10 safety comment with hazard and precaution ;

hazard risk precaution

knife / scalpel injury cut away from hand

blood vessels biohazard / pathogens / allergy gloves / mask / PPE /

use disinfectant / wash hands

mass hanger falling injury suitable precaution to prevent injury

11 idea of repeat procedure with smaller mass intervals near to breaking mass ;

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Question Answer Marks

1(b)(i) 2
mass added / g length of vein / mm percentage increase in
length of ring of vein

0 21 0

10 36 71

20 38 81

30 40 90

40 41 95

50 41 95

three values correct ;;

one or two correct max 1

1(b)(ii) 1 to make a valid comparison (with other blood vessels / veins) ; 1

2 allows comparison as, initial / starting, length (of veins) is, not constant / AW ;

1(b)(iii) 1 correct orientation for axes and linear scale ; 3

2 axes labelled and units;

3 all points plotted correctly and line drawn accurately ;

1(b)(iv) 1 curve for artery starts at same point as the vein ; 2

2 curve for artery below curve for vein and does not intersect ;

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Question Answer Marks

1(b)(v) any two from: 2

1 starts at, same point / origin, as using percentage increase ;

2 (muscular) arteries have a thicker, wall / tunica media / muscle layer (than the vein)
or
3 (muscular) arteries have more (smooth) muscle (than the vein) ;

4 idea of (muscular artery) withstands more (blood) pressure so stretches less (than the vein) ;

1(b)(vi) any two from: 2

1 use smaller mass intervals ;

2 extend the range of the masses added ;

3 use a, force meter / Newton meter / data logger / AW, (to apply force) ;

4 attach a, pointer / fiducial mark, to the ring of blood vessel (to improve length measurement / removing parallax) ;

5 use, same / stated, width of blood vessel ;

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Question Answer Marks

2(a) 1 cm3 of stock solution to 149 cm3 of distilled water ; 2

(dilution factor is) 150 ;

2(b) any one from: 1

1 measure from, top of the soil / bottom of stem / AW, to top of the stem / AW ;

2 straighten the stem (while measuring length) ;

3 place string along stem, and measure length of string ;

2(c)(i) 1.9 ; 1

2(c)(ii) any one from: 1

1 (mean stem) length was measured, in / to the nearest, cm ;

2 many anomalies in the results / identified anomaly ;

3 no statistical test carried out ;

2(c)(iii) any one from: 1

1 measure lengths in mm ;

2 idea of repeat high concentration GA3 experiment (to check anomaly) ;

3 measure, at same time every day / for more days ;

4 measure more seedlings / increase sample size ;

2(d) (SE =) 0.067 ; 2

(95% CI =) 1.38  0.13 ;

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Question Answer Marks

2(e) any three from: 3

1 highest (concentration of) GA8 with, red light / 680 nm

or
lowest (concentration of) GA1 with, blue light / 470 nm
or
highest (concentration of) GA1, in the dark / with no light ;

2 lower (concentration of) GA1 for all wavelengths of light (compared to dark)
or
higher (concentration of) GA8 for all wavelengths of light (compared to dark) ;

3 95% CI, does not overlap (for the lower concentration of GA1 for all wavelengths of light), so there is a significant
difference
or
95% CI, does not overlap, (higher concentration of GA8 for all of the wavelengths of light), so there is a significant
difference ;

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