Int Gcse Combined Sci Biology Core Mark Scheme Jun19

INTERNATIONAL GCSE
COMBINED SCIENCE
9204/BC
Paper 1 Biology Core
Mark scheme
June 2019
Version: 1.0 Final
*JUN199204BC/MS*
MARK SCHEME – INTERNATIONAL GCSE COMBINED SCIENCE – 9204/BC – JUNE 2019
Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
responses to questions and that every associate understands and applies it in the same correct way.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Assessment Writer.
It must be stressed that a mark scheme is a working document, in many cases further developed and
expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
assessment remain constant, details will change, depending on the content of a particular examination
paper.
Further copies of this mark scheme are available from oxfordaqaexams.org.uk
Copyright © 2019 Oxford International AQA Examinations and its licensors. All rights reserved.
2
Level of response marking instructions

Level of response mark schemes are broken down into levels, each of which has a descriptor. The
descriptor for the level shows the average performance for the level. There are marks in each level.
Before you apply the mark scheme to a student’s answer read through the answer and annotate it (as
instructed) to show the qualities that are being looked for. You can then apply the mark scheme.
Step 1 Determine a level

Start at the lowest level of the mark scheme and use it as a ladder to see whether the answer meets the
descriptor for that level. The descriptor for the level indicates the different qualities that might be seen in
the student’s answer for that level. If it meets the lowest level then go to the next one and decide if it
meets this level, and so on, until you have a match between the level descriptor and the answer. With
practice and familiarity you will find that for better answers you will be able to quickly skip through the
lower levels of the mark scheme.
When assigning a level you should look at the overall quality of the answer and not look to pick holes in
small and specific parts of the answer where the student has not performed quite as well as the rest. If
the answer covers different aspects of different levels of the mark scheme you should use a best fit
approach for defining the level and then use the variability of the response to help decide the mark within
the level, ie if the response is predominantly level 3 with a small amount of level 4 material it would be
placed in level 3 but be awarded a mark near the top of the level because of the level 4 content.
Step 2 Determine a mark

Once you have assigned a level you need to decide on the mark. The descriptors on how to allocate
marks can help with this. The exemplar materials used during standardisation will help. There will be an
answer in the standardising materials which will correspond with each level of the mark scheme. This
answer will have been awarded a mark by the Lead Examiner. You can compare the student’s answer
with the example to determine if it is the same standard, better or worse than the example. You can then
use this to allocate a mark for the answer based on the Lead Examiner’s mark on the example.
You may well need to read back through the answer as you apply the mark scheme to clarify points and
assure yourself that the level and the mark are appropriate.
Indicative content in the mark scheme is provided as a guide for examiners. It is not intended to be
exhaustive and you must credit other valid points. Students do not have to cover all of the points
mentioned in the Indicative content to reach the highest level of the mark scheme.
An answer which contains nothing of relevance to the question must be awarded no marks.
3
AO / Spec.
Question Answers Extra information Mark
Ref.
group of organs 1 AO1
01.1 3.1.2.d
that perform a (particular) function allow with the same function 1
(A) stomach 1 AO1

01.2 3.2.3.a
(B) large intestine 1
lipase in this order 1 AO1

01.3 3.2.3.c
fatty acids 1
up to 40(oC) rate of reaction increased 1 AO2

3.2.3.b
after 40(oC) rate of reaction decreased allow enzyme stopped working at 50(oC) 1
01.4
allow rate of reaction increases and then
decreases at a faster rate for 2 marks
allow went up and down for 1 mark
allow outlier AO3
01.5 anomalous result 1
allow does not fit the pattern 3.2.3.b
(enzyme) denatured do not accept (enzyme) killed AO2
01.6 or 1 3.2.3.b
active site changed shape
Total 10
4
AO / Spec.
Ref.
AO1
02.1 protects the lungs / heart allow breathing 1
3.2.4.a
AO1
02.2 contracts / flattens / moves down 1
3.2.4.b
4 (breaths in 20 seconds) an answer of 12 (breaths per minute) scores 2 1
marks
AO2
02.3 4 × 3 = 12 (breaths per minute) 1
3.2.5.g
allow 8 x 3 = 24 for 1 mark
fluctuations greater than 0.5 l 1
AO2
02.4
3.2.5.g
more than 4 fluctuations in 20 s 1
any one from
• age
AO3
02.5 • health 1
3.2.5.g
• fitness
allow other correct factor
Total 7
5
AO / Spec.
Ref.
any one from

• find food
AO2
03.1 • avoid predators 1
3.3.2.f
• prevents drying out
allow maintain temperature
AO1
03.2 nervous system 1
3.4.1.a
any one from

• same time interval between touches
AO4
03.3 • same ‘type’ of touch allow description 1
3.3.2.f
• touch with the same object allow description
any two from

• touch worm gently
• keep Petri dish damp AO4
03.4 • provide food 2
3.2.2.f
• provide oxygen / air
• (appropriate) temperature
allow low light conditions
AO2
03.5 habituation 1
3.4.5.c
AO2
03.6 to save energy 1
3.4.5.c
6
less food for birds / other animals 1
less decomposition 1
AO3
03.7
3.3.2.a
allow soil is not aerated or soil contents are not
mixed
allow decomposing material accumulates
Total 9
7
AO / Spec.
Ref.
any one from:
• light
• water
04.1 • minerals 1 AO2
• disease 3.5.3.a
• space
• temperature
• pollution
R r
R RR Rr 2 marks for all 4 derivations correct AO2

04.2 2
1 mark for 2 or 3 derivations correct 3.5.3.g
r Rr rr
homozygous for r (allele) allow only r present in parents/offspring 1

AO2
04.3 or
3.5.3.g
no R (allele)
eating GM crops may affect human health 1

AO1
04.4
3.5.5.f
the effect of GM crops on wild flowers is not known 1
8
Level 2: Relevant reasons are identified, and there are attempts at logical linking. The resulting account is not
3–4
04.5 fully clear. AO3
3.5.5.d/e
Level 1: Points are identified and stated simply, but their relevance is not clear and there is no attempt at logical
1–2
linking.
No relevant content
0
Indicative content
• greater chance of crop surviving
• fewer insects / pests to eat the crops

• (fewer insects means) less leaf damage
• more photosynthesis/glucose
• more nutrients for growth not fighting disease
• crops grown in more places

• not affected by global warming
• can be grown at any time of the year
• weed-killers can be used without affecting crops

• (fewer weeds means) less competition for space/minerals/light
• more (photosynthesis/) growth
• more nutritious food produced
chromosomes are copied before the cell divides 1
AO1
04.6
3.5.2.e
the new cells are genetically identical 1
AO1
04.7 DNA 1
3.5.3.h
Total 13
9
AO / Spec.
Ref.
AO2
05.1 dropping an unexpectedly hot object 1
3.4.1.c
AO2
05.2 322 (ms) 1
3.4.1.a
first 2 responses (in test 1) are higher than the others 1
AO3
05.3
3.4.1.a
because she got better with practice 1
Change Control Measure all 4 correct scores 3 marks
 3 correct scores 2 marks
3 AO4
05.4 
1/2 correct scores 1 mark 3.4.1


allow converse AO3
05.5 older people have a slower reaction time 1
3.4.1.a
to minimise the effect of anomalies / variation 1
or
not everyone in the same age group has the same reaction
AO3
05.6 time
3.6.1
or
to calculate a mean
allow a particular older person may have faster
reaction time than a young person
Total 9
10
AO / Spec.
Ref.
Cell Tissue Organ

Gamete 
1 AO1
06.1 Leaf  3.1.4.a/b;
1 3.5.3.b
Phloem 
Root  1
(similarity)
any one from 1
• cell wall
• cytoplasm
• DNA
• cell membrane
• ribosomes
AO2
06.2
1 3.1.1.b/c
(difference)
spirogyra has allow converse
any one from
• nucleus
• chloroplast
• no plasmid
• vacuole
photosynthesis 1 AO2
06.3 3.1.1.b,
has a chloroplast 1 3.2.1.b
11
nucleus in this order for 2 marks 2

chromosome
gene
allow 1 mark for
AO2
chromosome
06.4 3.5.3.c/i
gene
3.1.2
nucleus
or
gene
nucleus
chromosome
AO2
06.5 C 1
3.1.2
AO2
06.6 A, D 1
3.1.2
Total 11
12
AO / Spec.
Ref.
all 4 correct – 3 marks
2/3 correct – 2 marks
1 correct – 1 mark
07.1 3 AO2 3.3.3.e
60 an answer of 40(%) scores 2 marks 1

( × 100)
150 AO2
07.2
3.3.3.e
40(%) 1
150 (billion tonnes) added an answer of 10 billion tonnes more added than 1
removed scores 2 marks
AO3
07.3 140 (billion tonnes) removed 1
3.3.3.e
if no other mark awarded allow more carbon is
added than is removed for 1 mark
any three from
• used in respiration
• used to make starch if neither awarded allow used to make storage
• used to make fat molecules for 1 mark AO1
07.4 • used to make cellulose 3 3.2.1.d,
• used to make protein 3.3.3.e
if no other mark awarded allow reference to

plant growth for 1 mark
Total 10
13
AO / Spec.
Ref.
AO1
08.1 2
3.2.2.c
if neither mark awarded allow correct labels to

an atrium and a ventricle for 1 mark
AO1
08.2 pulmonary vein 1
3.2.2.e
14
two separate circulation systems or

1
(because) blood through heart twice in one circulation of the
AO1
08.3 body
3.2.2.b/e
one for lungs and one for other organs
allow named organs 1
urea carried in plasma 1
(liver)  heart  lungs  heart  (kidneys) 1

or AO1/AO2
08.4
from liver in a vein and to kidney in an artery 3.2.2.a/e/i
at least one correctly named blood vessel eg vena cava, pulmonary artery, pulmonary 1
vein, aorta
fatty deposits block the (coronary) artery 1
less / no oxygen / glucose to heart muscle cells allow O2 1

do not accept O2 / O2
AO2
08.5 less / no respiration/energy do not accept (less) energy produced 1 3.2.2.e/j
3.2.5.f
so heart (muscle cells) can’t contract

or 1
heart muscle cells die
Total 12
15
AO / Spec.
Ref.
must include independent and dependent
1
squeezing rate will have an effect variable for 2 marks
AO2
09.1
3.2.5.l
on the length of time before muscle fatigue occurs allow on the length of time squeezing can
1
continue
Level 2: The plan would not necessarily lead to a valid outcome. Most steps are identified, but the plan is not 3–4
09.2 AO1
fully logically sequenced.
3.2.5.l
Level 1: The plan would not lead to a valid outcome. Some relevant steps are identified, but links are not made 1–2
clear.
No relevant content 0
Indicative content
• apparatus - stopwatch and hand exerciser
• use dominant hand
• fully squeeze handles of exerciser in and out
• squeeze at a rate of 1 repetition every 3 seconds/ described rate
• record the time it takes for hand to get fatigued
• repeats
• rest period between trials
• range of at least 4 more rates of repetition
bar graph do not accept line graph 1

AO2
09.3 3.2.5.l
all plotting correct 1 mark if one error 2
0 marks if more than 1 error.
16
AO3
09.4 increase in squeezing rate caused muscles to fatigue faster 1 3.2.5.l
Total 10
17
AO / Spec.
Ref.
carbon dioxide word takes precedence 1
AO1
10.1 allow CO2
3.2.5.m
ignore CO2 / CO2
AO4
10.2 to keep oxygen / air out of the solution 1
3.2.5
monitor water bath temperature allow use thermometer 1
AO4
10.3
add hot / cold water (to maintain 30oC) allow use Bunsen burner or water bath (to warm 1 3.2.5
up)
so all the oxygen is used up allow idea of yeast acclimatising 1
or
AO3
10.4 so no aerobic respiration
3.2.5
or
so yeast are respiring anaerobically
sucrose 1
AO3
10.5
3.2.5.m
most air bubbles (per min so bread rises more) 1
(high temperature) kills the yeast 1
or
AO2/AO3
10.6 (high temperature) denatures enzymes (in the yeast) 1
3.2.5
so no more respiration / CO2 produced
Total 9
18

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INTERNATIONAL GCSE

Further copies of this mark scheme are available from oxfordaqaexams.org.uk

Level of response marking instructions

Step 1 Determine a level

Step 2 Determine a mark

(A) stomach 1 AO1

lipase in this order 1 AO1

up to 40(oC) rate of reaction increased 1 AO2

any one from

any one from

any two from

less food for birds / other animals 1

R RR Rr 2 marks for all 4 derivations correct AO2

homozygous for r (allele) allow only r present in parents/offspring 1

eating GM crops may affect human health 1

• greater chance of crop surviving

• fewer insects / pests to eat the crops

• crops grown in more places

• weed-killers can be used without affecting crops

Cell Tissue Organ

nucleus in this order for 2 marks 2

2/3 correct – 2 marks

60 an answer of 40(%) scores 2 marks 1

if no other mark awarded allow reference to

if neither mark awarded allow correct labels to

two separate circulation systems or

(liver)  heart  lungs  heart  (kidneys) 1

less / no oxygen / glucose to heart muscle cells allow O2 1

so heart (muscle cells) can’t contract

bar graph do not accept line graph 1

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