!
1 2 3 4 5 6 7
8 9 10 1112 13 14
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Water is split into oxygen
And hydrogen/ hydrogen ions
Light energy raises electrons t
Electrons received by photosyst
ATP
Provides energy
Reduced NADP/ NADPH
Reduces GP/ passes H to GP
Electrons in chlorophyll/
photosystems are raised to
higher energy level by
light
Electrons pass along
transfer chain
The energy is used to make
ATP from ADP and Pi
Electrons (and H+) reduce
NADP
H +come from photolysis
They are used in the light
independent stage/ Calvin
cycle
To convert GP to TP
The reduced NADP supplies
hydrogen atoms
The ATP supplies energy
Reduced by electrons
From photolysis / chlorophyll
RuBP reacts with
carbon dioxide to
form 2 molecules of
GP
Less is used to combine
with carbon dioxide /
Less used to form GP
Carbon dioxide is used
in photosynthesis /
Will allow detection
ATP and reduced NADP are not
produced
GP is not being used to form
RuBP
Used in respiration/
formation of starch/
cellulose
Original / 100% reading
light meter reading
–
Oxygen produced / change
in oxygen concentration in
unit time
Oxygen is produced in light
dependent reaction
Light energy absorbed by
chlorophyll/ excites
electrons
Electrons leave the
chlorophyll
Photolysis of water occurs
Electrons replaced in
chlorophyll
Red light leads to more
photosynthesis / more oxygen
produced with red light
(compared to green light)
More red light absorbed (by
chlorophyll)
(Most) green light reflected
Water is split using light e
It provides electrons/ hydro
Replaces the electrons lost
Provides hydrogen ions for A
It binds to chlorophyll
molecules
Prevents the release/
absorption of electrons
Stops the movement of
electrons down the first
Less ATP produced
For the Calvin cycle/
light independent
reaction
So less sugar produced
for respiration
Rate of reaction becomes
Reduced NADP/
NADPH
2
Less GP formed
So less TP
Less RuBP regenerated/ made
Less CO 2 taken up
High levels of oxygen reduce
the rate of photosynthesis,
effect greater at higher
temperatures
Higher concentration means
more effective competitor/
ATP
Reduced NADP / NADPH
O 2 produced / CO 2 taken
up
To ensure a high rate of
photosynthesis/ so that
neither factor is limiting
More photosynthesis when
the dark period increased
from 3 to 17ms
Even though amount of
Products made in the light
dependent system have been
used up (in 17ms)
Few/no trees already
present
Species X has high rate
of photosynthesis at
high light intensities
Species X trees grow
Species X trees will
provide shade / reduce
light intensity
Species Z grows best/ more
photosynthesis in low
High concentration of CO 2 at
night/ darkness
No photosynthesis in dark/
light required for light
dependent stage
Plants respire [all the time]
In the light there is a net
uptake of CO 2 by plants/ rate
of photosynthesis is higher
than rate of respiration
Decrease in CO 2 concentration
Carbon dioxide combines with
ribulose bisphosphate/ RuBP
To produce two molecules of
glycerate 3-phosphate/ GP
GP is reduced to TP
Which requires reduced
NADP/NADPH
And energy from ATP
24 2 =
1  576 =
576
0.0017
0.001
7
Radius/ diameter of the
capillary tube
Bubble in CO 2
Add(dissolved) hydrogen
carbonate
Oxygen used in respiration
Oxygen would dissolve in the
water
Oxygen may leak from the
apparatus
May remain as bubble in leaf
air spaces
Nitrogen present in the air
in the leaf/
Will leave leaf with the
oxygen/
May come
outthan
of solution
Level
higher
expected/
normal/ in atmosphere
Plant is respiring/ produces CO 2
CO 2 has been added to the water/
present in excess
Comes out of solution
Intensity:
less/lower light intensity
in deep water
pigments can absorb what
Wavelength:
light
is
notthere
all wavelengths
of light
can penetrate/ mainly
short
wavelengths/ mostly blue light
penetrates
pigments can absorb these
Light
intensity
Some other factor is now
limiting the rate
e.g. carbon dioxide
concentration or
1
Rate increases when
temperature increases from
15 O C to 25 O C
Rate increases when carbon
dioxide concentration
Enzymes will (start to)
denature
E.g. rubisco
Active site will change
shape
Less photolysis
Less ATP produced
Named step in Calvin cycle
affected
Increased rate of
transpiration
Less reflection of light
More light absorbed
More wavelengths of light
absorbed
More ATP / reduced NADP produced
Temperature of leaf will
increase
Enzymes work more effectively
Reduces limiting effect of light
intensity / temperature
As a control
To show that light is pro
Cut discs the same siz
To give same surface a
Cut discs from same/si
To give same amount of
Carry out at same tempe
Temperature affects enzy
Carry out repeats
To calculate
means/identify
anomalous results
Place lamp same distan
To give same light int
Use filters of same th
To give same light inte
Carry out in darkened
To ensure only one wav
Give CO2 in excess
So that CO2 is not a li
Use same volume/concent
So that colour changes
Put heat sink between
To minimise temperature
Chlorophyll a
Chlorophyll reflects/does n
Little/no photosynthesis/li
Little/no photolysis/ split
Little/no CO2 taken up
Some CO2 produced in respir
CO2 increases acidity/ lowe
Photosynthesis is control
Optimum temperature can
heaters/
be controlled with
ventilation/air
CO2 can be increased by
conditioning
burning
gas/paraffin
CO2 will not be a
will
increase
limiting
factor/ Calvin
cycle
Chlorophyll a
Chlorophyll b
Carotene
Obtaining
individual
organelles
Xanthophyll
Fucoxanthin
From water
Water is split in
photolysis
Linked to photosystem 2
Reduced NADP/
NADPH
Chloroplasts retain
biochemical activity
Prevent activity of
(lysosome) enzymes
Prevent membrane/protein
damage
Buffer keeps pH constant
No (net) water movement/
osmosis
So no change in volume/
turgidity of chloroplasts
blue
gree
n
Boiled suspension:
enzymes denatured
change in tertiary
structure/ active site
no photolysis
no hydrogen released
DCPIP remains blue/
oxidised
The End
!!!!!