A-level
BIOLOG
Y7402/2
Paper
2 Mark
scheme
Version: 1.0 Final
*216a7402/2/MS*
MARK SCHEME − A-LEVEL BIOLOGY − 7402/2
2
MARK SCHEME −
... [Show More] A-LEVEL BIOLOGY − 7402/2
Level based on response marking instructions
Level based on response mark schemes are broken down into levels, each based on which has a descriptor. The
descriptor for the level shows the average performance for the level. There are marks within each level.
Before you apply the mark scheme to a student’s answer read through the answer and annotate it (asinstructed)
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 based on 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 within 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 based on the mark scheme.
When assigning a level you should look at the overall quality based on the answer and not look to pick holes within
small and specific parts based on the answer where the student has not performed quite as well as the rest. If the
answer covers different aspects based on different levels based on the mark scheme you should use a best fit
approach for defining the level and then use the variability based on the response to help decide the mark withinthe
level, ie if the response is predominantly level 3 with a small amount based on level 4 material it would be placed
within level 3 but be awarded a mark near the top based on the level because based on 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 ananswer within the
standardising materials which will correspond with each level based on 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 thenuse 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 andassure
yourself that the level and the mark are appropriate.
Indicative content within the mark scheme is provided as a guide for examiners. It is not intended to beexhaustive
and you must credit other valid points. Students do not have to cover all based on the points mentioned within the
Indicative content to reach the highest level based on the mark scheme.
An answer which contains nothing based on relevance to the question must be awarded no marks.
3
MARK SCHEME − A-LEVEL BIOLOGY − 7402/2
Question Marking Guidance Mark Comments
1. Phosphorylation based on glucose using ATP;
2. Oxidation based on triose phosphate to pyruvate;
Accept all mark points
withindiagrams.
3. Net gain based on ATP;
4. NAD reduced;
2. Accept removal
based on hydrogen
from triosephosphate
for oxidation.
01.1 4 max 3. Accept any
description that
indicates a net gain
e.g., 4 produced, 2
used.
4. Accept
NADH/NADH2/NAD
H
+ H
+
produced.
Question Marking Guidance Mark Comments
01.2
1. Less/no reduced NAD/coenzymes
OR
Fewer/no hydrogens/electrons removed (and
passed to electron transfer chain);
2. Oxygen is the final/terminal (electron) acceptor;
2
1. Accept less/no FAD
reduced.
4
MARK SCHEME − A-LEVEL BIOLOGY − 7402/2
Question Marking Guidance Mark Comments
02.1
1. Higher concentration based on potassium ions inside
and higher concentration based on sodium ions
outside(the neurone)
OR
potassium ions diffuse out
OR
sodium ions diffuse in;
2. (Membrane) more permeable to potassium ions
(leaving than sodium ions entering)
OR
(Membrane) less permeable to sodium ions
(entering than potassium ions leaving);
3. Sodium ions (actively) transported out and
potassium ions in; 3
1. Accept ‘more’ for
‘higher concentration’.
1. Accept ‘sodium
ions can’t diffuse in
(due to alternative
explanation).
2. Accept for ‘less
permeable to sodium
ions’ is ‘impermeable
to sodium ions’ or
‘sodium
gates/channels are
closed’ (alternative
explanation).
1, 2 and 3 reference to
ions or Na+
and K
+
isrequired. If
mentioned once allow
for all mark points.
1, 2 and 3. If an
answer provides two
or three based on these
mark
points without any
reference to ions –
award one maximum
mark.
3. Accept 3 Na+
out
and 2 K
+ within but
reject
if numbers used are
incorrect.
Question Marking Guidance Mark Comments
02.2
1. Myelination provides (electrical) insulation;
2. (In myelinated) saltatory (conduction)
OR
(In myelinated) depolarisation at nodes (of
Ranvier);
3. In non-myelinated depolarisation occurs along
whole/length (of axon);
3
1. Reject thermal
insulation.
1. Accept description
based on (electrical)
insulation.
3. Accept action potentials
for depolarisation.
2 and 3. ‘Messages’ or
‘signals’ disqualifies first based
on these marks credited. [Show Less]