CAMBRIDGE INTERNATIONAL AS & A LEVEL BIOLOGY: COURSEBOOK
Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded
may be different.
Coursebook answers
Chapter 13
Exam-style questions
The mark schemes, suggested answers and
comments that appear here were written by the
author(s). In examinations, the way marks would
be awarded to answers like these may be different.
1
a allows chlorophyll and other pigments to
be arranged into photosystems ;
provides a large surface area for pigments ;
increases efficiency of light harvesting ;
Notes about mark schemes
allows electron carriers to be arranged
appropriately ;
A or accept indicates an alternative acceptable
answer.
provides structure for proton gradient for
chemiosmosis ;
R = reject. This indicates a possible answer that
should be rejected.
anchors ATP synthase ; ; The bold semicolon indicates the award of
1 mark.
b
/ This indicates an alternative answer for the same
mark. The alternatives may be separated from the
rest of the answer by commas.
Structural feature Shared by chloroplast
and typical
prokaryotic cell
( ) Text in brackets is not required for the mark.
circular DNA
✓
Underlining This is used to indicate essential
word(s) that must be used to get the mark.
DNA combined
with structural
protein to form
chromosomes
✗
ribosomes about
18 nm in diameter
✓
complex arrangement of internal
membranes
✗
peptidoglycan
wall
✗
size ranges overlap
✓
AW means ‘alternative wording’. It is used to
indicate that a different wording is acceptable
provided the essential meaning is the same, and is
used where students’ responses are likely to vary
more than usual.
AVP means ‘additional valid point’. This means
accept any additional points given by the student
that are not in the mark scheme, provided they
are relevant. But accept only as many additional
points as indicated by the bold semicolons, e.g.
AVP ; ; means award a maximum of 2 extra marks.
ORA means ‘or reverse argument’ and is used
when the same idea could be expressed in the
reverse way. For example: ‘activity increases
between pH2 and pH5 ORA’ means accept
‘activity decreases between pH5 and pH2’.
max. This indicates the maximum number of
marks that can be given.
1
[max. 5]
2
[6]
[Total: 11]
a
photolysis of water occurs in light ;
H+ released ;
accepted by DCPIP / methylene blue ;
colourless when reduced ;
Cambridge International AS & A Level Biology © Cambridge University Press 2020
CAMBRIDGE INTERNATIONAL AS & A LEVEL BIOLOGY: COURSEBOOK
shows ‘reducing power’ of chloroplasts ;
[max. 4]
b
NADP ;
[1]
a
concentration of carbon dioxide ;
temperature ; a light-dependent photochemical stage ;
electron emitted by chlorophyll of
photosystem II does not return to
that chlorophyll (but is absorbed by
photosystem I and electron emitted by
photosystem I is absorbed by NADP) ;[2]
a light-independent temperaturedependent stage ;
photochemical reactions are not affected
by temperature ;
photophosphorylation:
at low light intensities, light intensity is
the rate-limiting factor ;
synthesis of ATP using light energy in
photosynthesis in a chloroplast ;
at high light intensities and low
temperatures, temperature is the ratelimiting factor ;
[max. 5]
oxidative phosphorylation:
c
[2]
6
a
of different wavelengths of light by a
compound ;
NADP:
hydrogen carrier in photosynthesis ;
action spectrum:
[2]
[Total: 6]
a and b
CO2 (1C)
absorption spectrum:
a graph of the absorbance ;
hydrogen carrier in respiration ;
4
[Total: 10]
NAD:
[4]
c shows that there are two sets of reactions
in photosynthesis ;
non-cyclic photophosphorylation:
synthesis of ATP using energy
released from the electron transport
chain in aerobic respiration in a
mitochondrion ;
light intensity ;
light wavelength ;
cyclic photophosphorylation:
electron emitted by chlorophyll of
photosystem I returns to chlorophyll by a
series of carriers ;
b
a limiting factor: one factor, of many
affecting a process, that is nearest its
lowest value and hence is rate-limiting ;[1]
b
[Total: 5]
3
5
rubisco
active here
a graph of the rate of a process ;
e.g. photosynthesis at different
wavelengths of light ;
[4]
b number of bubbles shows rate of
photosynthesis ;
rate similar at 450 nm (blue) and 650 nm
(red) ; these are wavelengths that are
absorbed by chlorophyll ;
rate, much lower / refer to figures, at
550 nm (green) ;
RuBP (5C)
GP/PGA (3C)
very little absorbed by any pigment ;
[max. 4]
[Total: 8]
triose phosphate (3C)
[Total: 5]
2
Cambridge International AS & A Level Biology © Cambridge University Press 2020