Photosynthesis PhysicsAndMathsTutor.com
Mark scheme - Photosynthesis
Questio
Answer/Indicative content Marks Guidance
n
1 C 1
Total 1
2 B 1
Total 1
3 D✓ 1
Total 1
Examiner’s Comments
Despite the novel approach, few were
significantly challenged by this question
which was answered correctly by a high
4 C✓ 1 proportion of candidates. However, some
candidates were caught out by the presence
of NAD in options A and B as opposed to
NADP needed for the correct response,
option C.
Total 1
Examiner’s Comments
Candidates did have to process some
information from a graph in this question and
choose appropriate values to perform a
percentage change calculation. Whilst
5 C✓ 1
candidates often struggle with such
calculations in the question styles of section
B, this posed little problem for nearly 80% of
candidates who identified option C as the
correct response.
Total 1
Examiner’s Comments
There were many correct responses for the
reason why V.minimum did not need
6 A✓ 1
chloroplasts with candidates demonstrating
the ability to make deductions from
information provided.
Total 1
Examiner’s Comments
7 D✓ 1
,Photosynthesis PhysicsAndMathsTutor.com
Option A provided a distractor and common
incorrect response to the correct option, C in
this question as statement 1, whilst correct,
was irrelevant to the question being asked
about ecdysone.
Option B provided a distractor and common
incorrect response to the correct option, D, in
this question. This is possibly due to
misconceptions surrounding the synthesis of
ATP by different methods of phosphorylation.
Total 1
Examiner’s Comments
Candidates that understood the principles of
light absorption by pigments chose D as the
1
8 D✓ correct option. However, the question proved
(AO2.7)
challenging for some candidates and there
was confusion as to which wavelengths of
light (blue or red) were absorbed or reflected
by the blue pigments in the Cyanobacteria.
Total 1
IGNORE + or -
ALLOW two marks
if answer is correct but not to two S.F.
ALLOW two marks
if answer is incorrect
for correct calculation e.g.
OR
9 a i 9.7 x 10-3 3
OR
ALLOW one mark for
0.0097 ✓✓✓
0.052 × π × 3.7
OR
0.029
Examiner’s Comments
Mathematical skills were being assessed in
this part of the question. To achieve all three
marks a great deal of processing was
required. Candidates had to choose the
, Photosynthesis PhysicsAndMathsTutor.com
correct figure from Table 22.1, calculate the
radius using the figure given for diameter,
substitute their figures into the equation
provided and then divide by three to obtain a
response in mm3 per hour. Many candidates
were credited with all three marks. Many
others gained two marks for a correct
calculation because they had not written their
response to two significant figures. Some
candidates appeared to forget to divide by
three and gained one mark, others used the
diameter instead of the radius in their
calculation which was not credited.
ALLOW one mark if answer is correct but
‘decrease’ has been calculated so response
given as ‘minus’ number
140 (two s.f.) /.7 /
ii 2
141..6. ✓✓ If answer is incorrect ALLOW one mark for
OR
ALLOW Calvin cycle / light independent
stage for photosynthesis throughout
iii removing CO2 would prevent 1 max
ALLOW e.g. so they could still
photosynthesis ✓
photosynthesise
e.g. CO2 needed for photosynthesis
CO2 would be a limiting factor for
photosynthesis ✓
‘at 1510 (lux)’ only needs to be mentioned
once throughout
ALLOW at 1510 (lux) compensation point
at 1510 (lux) the distance moved
has been reached
by the fluid (in respirometer) is ,
zero / 0 ✓
b 2 max Examiner’s Comments
at 1510 (lux) rate of
photosynthesis is equal to rate of
Many candidates demonstrated the ability to
respiration ✓
use the data in Table 22.1 to describe the
at 1510 (lux) there is no net
results for 1500 lux and conclude from this
change in volume in the
that the rates of respiration and
respirometer ✓
photosynthesis were equal, thereby gaining
both marks.
Total 8
IGNORE reference to external membrane
10 2 max
ALLOW plants (chloroplasts) have more
Mark scheme - Photosynthesis
Questio
Answer/Indicative content Marks Guidance
n
1 C 1
Total 1
2 B 1
Total 1
3 D✓ 1
Total 1
Examiner’s Comments
Despite the novel approach, few were
significantly challenged by this question
which was answered correctly by a high
4 C✓ 1 proportion of candidates. However, some
candidates were caught out by the presence
of NAD in options A and B as opposed to
NADP needed for the correct response,
option C.
Total 1
Examiner’s Comments
Candidates did have to process some
information from a graph in this question and
choose appropriate values to perform a
percentage change calculation. Whilst
5 C✓ 1
candidates often struggle with such
calculations in the question styles of section
B, this posed little problem for nearly 80% of
candidates who identified option C as the
correct response.
Total 1
Examiner’s Comments
There were many correct responses for the
reason why V.minimum did not need
6 A✓ 1
chloroplasts with candidates demonstrating
the ability to make deductions from
information provided.
Total 1
Examiner’s Comments
7 D✓ 1
,Photosynthesis PhysicsAndMathsTutor.com
Option A provided a distractor and common
incorrect response to the correct option, C in
this question as statement 1, whilst correct,
was irrelevant to the question being asked
about ecdysone.
Option B provided a distractor and common
incorrect response to the correct option, D, in
this question. This is possibly due to
misconceptions surrounding the synthesis of
ATP by different methods of phosphorylation.
Total 1
Examiner’s Comments
Candidates that understood the principles of
light absorption by pigments chose D as the
1
8 D✓ correct option. However, the question proved
(AO2.7)
challenging for some candidates and there
was confusion as to which wavelengths of
light (blue or red) were absorbed or reflected
by the blue pigments in the Cyanobacteria.
Total 1
IGNORE + or -
ALLOW two marks
if answer is correct but not to two S.F.
ALLOW two marks
if answer is incorrect
for correct calculation e.g.
OR
9 a i 9.7 x 10-3 3
OR
ALLOW one mark for
0.0097 ✓✓✓
0.052 × π × 3.7
OR
0.029
Examiner’s Comments
Mathematical skills were being assessed in
this part of the question. To achieve all three
marks a great deal of processing was
required. Candidates had to choose the
, Photosynthesis PhysicsAndMathsTutor.com
correct figure from Table 22.1, calculate the
radius using the figure given for diameter,
substitute their figures into the equation
provided and then divide by three to obtain a
response in mm3 per hour. Many candidates
were credited with all three marks. Many
others gained two marks for a correct
calculation because they had not written their
response to two significant figures. Some
candidates appeared to forget to divide by
three and gained one mark, others used the
diameter instead of the radius in their
calculation which was not credited.
ALLOW one mark if answer is correct but
‘decrease’ has been calculated so response
given as ‘minus’ number
140 (two s.f.) /.7 /
ii 2
141..6. ✓✓ If answer is incorrect ALLOW one mark for
OR
ALLOW Calvin cycle / light independent
stage for photosynthesis throughout
iii removing CO2 would prevent 1 max
ALLOW e.g. so they could still
photosynthesis ✓
photosynthesise
e.g. CO2 needed for photosynthesis
CO2 would be a limiting factor for
photosynthesis ✓
‘at 1510 (lux)’ only needs to be mentioned
once throughout
ALLOW at 1510 (lux) compensation point
at 1510 (lux) the distance moved
has been reached
by the fluid (in respirometer) is ,
zero / 0 ✓
b 2 max Examiner’s Comments
at 1510 (lux) rate of
photosynthesis is equal to rate of
Many candidates demonstrated the ability to
respiration ✓
use the data in Table 22.1 to describe the
at 1510 (lux) there is no net
results for 1500 lux and conclude from this
change in volume in the
that the rates of respiration and
respirometer ✓
photosynthesis were equal, thereby gaining
both marks.
Total 8
IGNORE reference to external membrane
10 2 max
ALLOW plants (chloroplasts) have more
