PHOTOSYNTHESIS
Why does a leaf look green?
How much of the light absorbed is
used?
Absorption spectrum of chlorophyll
Structure of a chloroplast
thylakoid
(thylakoids stacked
like pancakes)
Light-dependent reactions:
First stage of photosynthesis
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Photolysis of water:
energy absorbed by
chlorophyll is used to
split water molecules
into hydrogen and
oxygen.
Oxygen is released as
a waste product.
ATP is produced due
to photolysis.
Light-independent reactions
Second stage of photosynthesis
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Also known as Calvin
cycle
Carbon dioxide is
absorbed to produce
glucose.
The convertion from gas
to organic molecules is
called carbon fixation.
Hydrogen release in
photolysis and ATP are
used in this second stage
to produce glucose.
To sum up
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What does photolysis mean?
When and where does it occur?
What is considered a waste product in lightdependent reactions?
For what product is carbon dioxide absorbed?
What is carbon fixation?
Photosynthesis summary
plateau
CO2 is a substrate in an
enyme-catalysed lightdependent reaction.
At low CO2 concentration, rate is
positively correlated with concentration
plateau
At low light intensity, rate of photosynthesis is
proportional to light intensity.
Optimum
temperature
Increased temp.
gives increased
energy and
increased rate of
photosynthesis
Above the
optimum temp.,
enzymes are
denatured and
rate drops steeply.
Which enzymes are
used in respiration?
Rate of photosynthesis
What are the conditions of each of these trials?
Light intensity
Photosynthesis
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What is the importance (for all
living organisms) the process of
photosynthesis?
What is the most convenient
method to measure
photosynthesis?
What factors must be consider
when you measure
photosynthesis?
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When a process is influenced by
several factors which one
determines the rate at which the
process proceeds?
What organic molecule is
produce and what gas is given
off during photosynthesis?
What are the two main groups
of photosynthesis pigments?
What is the best wavelength for
absorption?
Questions examples