Mark Scheme

(Results)

November 2020

Pearson Edexcel GCSE

In Combined Science (1SC0) Paper 2BH
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Summer 2020
Publications Code 1SC0_2BH_2011_MS
All the material in this publication is copyright
© Pearson Education Ltd 2020
General Marking Guidance

• All candidates must receive the same treatment. Examiners must mark the first
candidate in exactly the same way as they mark the last.
• Mark schemes should be applied positively. Candidates must be rewarded for
what they have shown they can do rather than penalised for omissions.
• Examiners should mark according to the mark scheme not according to their
perception of where the grade boundaries may lie.
• There is no ceiling on achievement. All marks on the mark scheme should be
used appropriately.
• All the marks on the mark scheme are designed to be awarded. Examiners
should always award full marks if deserved, i.e. if the answer matches the mark
scheme. Examiners should also be prepared to award zero marks if the
candidate’s response is not worthy of credit according to the mark scheme.
• Where some judgement is required, mark schemes will provide the principles
by which marks will be awarded and exemplification may be limited.
• When examiners are in doubt regarding the application of the mark scheme to
a candidate’s response, the team leader must be consulted.
• Crossed out work should be marked UNLESS the candidate has replaced it with
an alternative response.
Mark schemes have been developed so that the rubrics of each mark scheme reflects the characteristics
of the skills within the AO being targeted and the requirements of the command word. So for example
the command word ‘Explain’ requires an identification of a point and then reasoning/justification of the
point.
Explain questions can be asked across all AOs. The distinction comes whether the identification is via a
judgment made to reach a conclusion, or, making a point through application of knowledge to
reason/justify the point made through application of understanding. It is the combination and linkage
of the marking points that is needed to gain full marks.
When marking questions with a ‘describe’ or ‘explain’ command word, the detailed marking guidance
below should be consulted to ensure consistency of marking.
Assessment Command Word
Objective

Strand Element Describe Explain

AO1 An answer that combines the An explanation that links

marking points to provide a logical identification of a point with
description reasoning/justification(s) as required

AO2 An answer that combines the An explanation that links

marking points to provide a logical identification of a point (by applying
description, showing application of knowledge) with
knowledge and understanding reasoning/justification (application
of understanding)

AO3 1a and An answer that combines points of

1b interpretation/evaluation to provide
a logical description

AO3 2a and An explanation that combines

2b identification via a judgment to
reach a conclusion via
justification/reasoning

AO3 3a An answer that combines the

marking points to provide a logical
description of the
plan/method/experiment

AO3 3b An explanation that combines

identifying an improvement of the
experimental procedure with a
linked justification/reasoning
Question Answer Additional Mark
number guidance
1(a) An explanation including the (2)
following:

• lower surface (of leaf) is not accept water would

in contact with air / is in enter the stomata
water (1)

• so gas exchange cannot accept oxygen

occur (1) /carbon dioxide
/water (vapour)

accept reduced/no
transpiration

Question Answer Mark

number
1(b) (i) D chloroplast (1)

The only correct answer is D chloroplast

A is incorrect because the nucleus does not

photosynthesise

B is incorrect because the vacuole does not

photosynthesise

C is incorrect because the mitochondrion does not

photosynthesise

Question Answer Mark

number
1(b)(ii) C sucrose (1)

The only correct answer is C sucrose

A is incorrect because glycerol is not a sugar

B is incorrect because although ribose is a sugar this is

found in DNA

D is incorrect because starch is not a sugar

Question Answer Additional guidance Mark
number
1(b)(iii) A description including two from: (2)

• in the phloem (1) reject xylem

• dissolved (in water) (1)

• by translocation (1)

• using active transport (1) accept by diffusion

Question Answer Mark

number
1(c) An explanation including three of the following: (3)

• because {conditions / named conditions} are

suitable for {growth / photosynthesis} /conditions
similar to native conditions /it is adapted to the
conditions (1)

• it outcompeted the natural plants (1)

• therefore, it {grows / reproduces} (1)

• as no natural herbivores {eat it / restrict it} (1)

Question 1 = 9 marks
Question Answer Mark
number
2(a)(i) 6 / six (1)

Question Answer Mark

number
2(a)(ii) D cell wall, chloroplast, large vacuole. (1)

The only correct answer is D cell wall, chloroplast, large

vacuole

A is incorrect because both the cell membrane and nucleus

are also found in animal cells

B is incorrect because the cell membrane and cytoplasm

are also found in animal cells

C is incorrect because the nucleus is also found in animal

cells

Question Answer Additional guidance Mark

number
2(b)(i) Substitution (2)

(50 – 30 =) 20 (1)

(20 ÷ 50 x 100 =) - 40(%) Accept 40%

award full marks for

answer without working

Question Answer Additional guidance Mark

number
2(b)(ii) Any two from: (2)

• variety of potato (1) accept type / species

• mass of potato (1) accept weight/size
• age of potato (1)
• temperature (1)
• storage conditions/humidity
(1)
accept potato cells
taken from the same
part of each potato
Question Indicative content Additional guidance Mark
number
2(b)(iii) (1)
for energy / respiration ignore make / produce
energy

accept to produce ATP

Question Indicative content Additional guidance Mark

number
2(b)(iv) Any two from: (2)

• enzyme / amylase / accept maltase

carbohydrase (1)

• starch fits into the

active site (1)

• bonds (between glucose accept polymer broken

molecules in starch) down into monomers
broken (1)

Question 2 = 9 marks
Question Answer Mark
number
3(a)(i) D proteins (1)

The only correct answer is D proteins

A is incorrect because carbohydrates are broken down by

carbohydrases /amylase

B is incorrect because lipids need to be digested by lipase

C is incorrect because fibre is not broken down by

enzymes

Question Answer Additional Mark

number guidance
3(a)(ii) An explanation linking the following: (2)

• to increase the surface area accept the food

of the food (1) molecules are
smaller

• so trypsin will break down accept there is a

more protein (1) faster rate of
reaction

Question Answer Additional Mark

number guidance
3(b)(i) Any one from: accept other (1)
valid variables
• temperature (1)
• the food used (1)
• the volume/size of test tube (1)

Question Answer Additional guidance Mark

number
3(b)(ii) Any one from: (1)

• use of a water bath/

description of alternative to
water bath (1)
• use food from the same
source (1)
• use test tubes which have
the same shape/volume (1)
accept other valid
variables to be
controlled
Question Answer Additional guidance Mark
number
3(c)(i) A description including two of the (2)
following:

• {as pH increases to pH accept time data

4/more acidic/low pH} the instead of pH data
time taken for the food to
digest {decreased/was
shorter} (1)

• The shortest time was pH 4 accept optimum pH

(1) was at pH 4

• {after pH 4 to pH 6/above accept time data

pH 4} the time taken for instead of pH data
the food to digest
increased/was longer} (1)

Question Answer Additional Mark

number guidance
3(c)(ii) substitution (2)
1.5 ÷ 42 = 0.035(7142857) (1) accept any
correctly
rounded value
e.g 0.036
Evaluation
0.04 (g per minute)
Question Answer Additional Mark
number guidance
3(c)(iii) An explanation linking two of the (2)
following:

• the rate of reaction at pH 1 is

slower (1)

• because enzymes are becoming accept so that

denatured /changing the the substrate
conformation of the active site / cannot bind
stopping enzyme substrate
complexes forming (1)

OR

• pH 4 is the optimum pH (1) accept rate of

reaction is
• because at pH 4 more enzyme fastest at pH 4
substrate complexes are formed /
more active sites of the enzyme
are filled (1)

Total for Question 3 = 11 marks

Question Answer Additional guidance Mark
number
4(a)(i) Linear scale on both axis (1) (3)

Plotted points (1) Accept accurate

plotting to ½ small
square

Correctly drawn graph (1) Accept dot to dot

drawing or a freehand
single line linking
points

Question Answer Additional guidance Mark

number
4(a)(ii) An answer including two of the (2)
following:

• wear gloves (1) accept cover {open

wounds/cuts}
• wash hands after handling
(1)

• sterilise equipment after

use / use sterile equipment
/ keep it in a sealed
container (1)

Question Answer Mark

number
4(b)(i) C platelets (1)

The only correct answer is C platelets

A is incorrect because erythrocytes are red blood cells

which carry oxygen

B is incorrect because lymphocytes are white blood cells

which are part of the immune system

D is incorrect because antibodies are part of the immune

response
Question Answer Additional guidance Mark
number
4(b)(ii) to stop blood loss / Accept (1)
prevent bacteria entering microorganisms/pathogen/virus
/stops bleeding (1) for bacteria

Question Answer Additional guidance Mark

number
4 (c) An answer linking two of the (2)
following:

• veins contain valves (1)

• which prevent the backflow accept keep blood

of blood (1) flowing in one
direction

OR
• veins have a large lumen
(1)

• to maximise blood flow (1) accept to carry a lot of

blood

Total for question 4 = 9 marks

Question Answer Additional guidance Mark
number
5(a) An answer comparing the (4)
following:

• the heart rate of person A

is higher than the heart
rate of person B (1)

• the heart rate of person A accept the rate of

increases more during increase for person A
exercise than person B (1) is higher than person
B
• the heart rate of person B
is level during exercise
whereas the heart rate of
person A keeps increasing
(1)

• person B returns to their

resting heart rate faster
than person A (1)

• comparative data analysis

(1)

Question Answer Additional guidance Mark

number
5 (b) Full marks for correct (3)
answer no working
Substitution:

65 x 61 (1) Conversion 61 ÷ 1000

(1)
Evaluation:

= 3 965 (1) 0.061 x 65 for

substitution mark
Conversion:

3 965 ÷ 1000 = 3.965 (litres per With 3.965/4 for

minute) evaluation mark

Accept 4 or any other

correct rounding
Question Answer Additional guidance Mark
number
5(c) An answer linking the following: (3)

• person A had a lower stroke

volume (1)

• pumps less blood out per accept the heart is

beat (1) not used to exercise

• so needed to have a higher

heart rate to get a similar
cardiac output (1)

• in order to exercise at the

same intensity (1)

• to supply oxygen/glucose to
the muscles (1)

Total for question 5 = 10 marks

Question Answer Additional Mark
number guidance
6(a)(i) causes the thyroid gland to enlarge / swell / (1)
increase thyroxine production (1)

Question Answer Mark

number
6(a)(ii) C endocrine system (1)

The only correct answer is C endocrine system

A is incorrect because the circulation involves the

movement of blood around the body

B is incorrect because the digestive system involves the

breakdown of food

D is incorrect because the urinary system deals with the

removal of excretory products

Question Answer Mark

number
6(b) An explanation including four of the following: (4)

• Low levels of thyroxine cause TRH to be produced

(1)

• (TRH is produced) in the hypothalamus (1)

• this causes TSH to be released (1)

• (TSH is released) from the pituitary (1)

• (TSH causes the) thyroid gland to produce thyroxine

(1)

• As thyroxine levels increase it inhibits the {release

of TRH / production of TSH} (1)
Question Indicative content Mark
number
*6(c) (6)

• There are four hormones involved in the menstrual

cycle oestrogen, progesterone, LH and FSH
• At the start of the cycle FSH causes the egg to
develop in the follicle
• FSH is released from the pituitary gland
• As progesterone and oestrogen levels are low
• Oestrogen levels start to rise
• Oestrogen is released from the ovaries
• This causes the lining of the uterus to build up
• High levels cause a surge of LH
• Released from the pituitary gland
• Causing ovulation
• An egg is released from the ovary
• Progesterone is produced
• From the corpus luteum
• This caused the lining of the uterus to be maintained
• If an egg is fertilised oestrogen and progesterone
levels remain high
• To maintain the lining of the uterus

Level Mark Descriptor

0 • No rewardable material.
Level 1 1-2 • Demonstrates elements of biological understanding, some of which
is inaccurate. Understanding of scientific ideas lacks detail. (AO1)

• Presents an explanation with some structure and coherence. (AO1)

Level 2 3-4 • Demonstrates biological understanding, which is mostly relevant but
may include some inaccuracies. Understanding of scientific ideas is
not fully detailed and/or developed. (AO1)

• Presents an explanation that has a structure which is mostly clear,

coherent and logical. (AO1)

Level 3 5-6 • Demonstrates accurate and relevant biological understanding

throughout. Understanding of the scientific ideas is detailed and fully
developed. (AO1)

• Presents an explanation that has a well-developed structure which

is clear, coherent and logical. (AO1)
Level Mark Descriptor

0 • No rewardable material.
Level 1 1-2 • Either a list of two or more hormones or a hormone linked to its role
in the menstrual cycle/or the endocrine gland it is released from

• There must be a coherent flow to the answer linking the correct

hormone with the correct role
Level 2 3-4 • At least two hormones of the menstrual cycle linked to their role or
the endocrine they are released from

• Answer must be correctly linked and in a logical order although the

candidate may start at any point within the menstrual cycle

Level 3 5-6 • Links at least three hormones of the menstrual cycle to their role
and endocrine gland they are released from

• Answer must be logically ordered and links must be correctly made

only minor errors are acceptable

Level Mark Examples of possible responses

0 • No rewardable material.
Level 1 1 • FSH and LH control the menstrual cycle / LH controls ovulation and
the uterus thickening (note an error here)

2 • LH controls ovulation
Level 2 3-4 • Oestrogen causes the uterus lining to thicken and LH to be released

• Oestrogen causes the uterus lining to thicken and LH to be released

from the pituitary gland

Level 3 5-6 • FSH causes the egg to mature in the follicle, oestrogen causes the
thickening of the uterus lining and causes LH to be released which
results in ovulation.

• FSH and LH are released from the pituitary gland, Oestrogen and
progesterone are released from the ovaries. FSH causes the egg to
mature in the follicle, oestrogen causes the thickening of the uterus
lining and causes LH to be released which results in ovulation.

Total for question 6 = 12 marks