In this bundle there are more than 5000 aqa a level biology questions and if you do every question and memorise the mark scheme you will get that A* without a doubt
1. (a) (i) In context of ATP formation
light raises energy level of / excites electrons;
pass through carriers;
energy released;
ATP formed from ADP + P;
In context of producing reduced NADP
+
protons / H ions;
from photolysis / water;
electrons; max 5
(ii) GP converted to triose phosphate / GALP;
this involves reduction;
reduced NADP provides reducing power / hydrogens;
ATP supplies energy for this reaction;
phosphate from ATP;
for production of RuBP; max 4
(b) Membranes / (disc) shape provides large surface for light absorption;
layering of membrane allows a lot of pigment;
(permeable) membrane allows diffusion of gases / carbon dioxide;
membranes provide surface for attachment of electron / hydrogen
acceptors;
stroma / matrix containing enzymes for Calvin cycle /
light–independent reactions; max 3
[12]
2. (a) (i) 5 3 3 6; 1
(ii) Stroma; 1
(iii) GP (accumulates as) cannot be converted to triose phosphate;
since this requires ATP / reduced NADP /
products of light-dependent reaction; 2
+
(b) Provides protons / hydrogen ions / H ;
for reduction of NADP;
OR
provides electrons;
which replace those lost from chlorophyll / photosystem (I or II); 2
[6]
,4. (a) Light absorbed by/strikes,chlorophyll/photosystem/PSI/PSII;
electrons excited;
pass down chain of carriers;
energy released/transferred;
producing ATP from ADP and phosphate;
reduced NADP/formed with electrons;
photolysis of water /allow light splits water;
+
(water) supplies protons/H ions to reduce NADP; max. 5
(b) RuBP converted to GP;
RuBP as carbon dioxide acceptor/combines with carbon dioxide;
GP converted to triose phosphate/TP/GALP;
this reaction is a reduction;
reduced NADP provides hydrogen;
ATP provides energy;
some triose phosphate/TP/GALP converted to glucose/carbohydrate;
some triose phosphate used to produce RuBP
ATP supplies phosphate for this reaction; max. 6
(c) Both processes involve:
Transfer of energy/conversion of energy from one form to another;
Use and produce ATP;
chain of electron carriers;
located on membranes;
detail of process (eg ref to chemiosmotic theory);
involve cycle of reactions;
oxidation and reduction/redox reactions involved;
and coenzymes;
processes are controlled by enzymes; max. 6
some common intermediates/GALP is common to both;
[17]
5. (a) (i) Correct answer (0.5%) awarded two marks;;
answer involving decimal point in wrong place but derived
correctly / correct working only awarded 1 mark 2
(ii) Some fails to encounter chloroplasts/chlorophyll in producers
(e.g. some absorbed by water);
reflection;
inappropriate wavelength; max. 2
(b) Only a certain amount of light energy available / not enough energy left;
respiratory loss between each trophic level / loss in faeces; 2
(c) Incorporated in tissues of decomposers;
passed on to other organisms in decomposer food chain;
lost in respiration by decomposers; max. 2
(d) (i) Excites/raises energy level of electrons;
which pass to carriers/leave chlorophyll; 2
(ii) Fall in production of triose phosphate/no more triose phosphate produced;
triose phosphate production requires ATP/reduced NADP;
produced during passage of electrons along electron transport chain; 3
(e) Energy is available more rapidly because released in single reaction /
does not go through as many processes;
ATP releases its energy in small/manageable quantities; 2
(f) (i) Activity / needs of cell linked to level of ATP / ADP ;
Sir George Monoux Sixth Form College 2
, link made between high level of one and low level of the other;
level of ADP linked to electron transport and ATP production; 3
(ii) Energy released as heat;
because not used to produce ATP; 2
[20]
Sir George Monoux Sixth Form College 3
, 6. Scientific Content (Maximum 16 marks)
Category Mark Descriptor
16
Most of the material of a high standard reflecting a comprehensive
understanding of the principles involved and a knowledge of
Good 14 factual detail fully in keeping with a programme of A level study.
Some material, however, may be a little superficial. Material is
accurate and free from fundamental errors but there may be minor
errors which detract from the overall accuracy.
12
10
A significant amount of the content is of an appropriate depth,
reflecting the depth of treatment expected from a programme of A
Average 8 level study. Generally accurate with few, if any fundamental
errors. Shows a sound understanding of most of the principles
involved.
6
4
Material presented is largely superficial and fails to reflect the
Poor 2 depth of treatment expected from a programme of A level study. If
greater depth of knowledge is demonstrated, then there are many
fundamental errors.
0
Sir George Monoux Sixth Form College 4
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