Photosynthesis
Where in the leaf does it happen?
Photosynthesis!
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Plants make food by the process called
photosynthesis. It is a process by which
chlorophyll uses the light energy from the sun
to convert CO2 & H20 into glucose & O2.
Photosynthesis occurs in unique organelles of
plant cells  CHLOROPLASTS!
Anatomy of the Chloroplast  Let’s draw it
Please Label on your sheet!
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Are the site of
photosynthesis
Found in green
plants, algae &
euglena
Football
shaped
Contain green
pigment
Granum
(stack of
thyllakoids)
Outer Membrane
Inner Membrane
Thyllakoid
Stroma
(fluid
filled)
Chloroplast Anatomy  It contains:
A) Double membrane which functions to:
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Support the organelle (encloses it)
Allow nutrients in.
Allow products to flow out.
B) Contains light-capturing sacs called
Thyllakoids (contain CHLOROPHYLL)
C) Stacks of thyllakoids Granum
D) Stroma –
1) liquid region granum float in
2) contain numerous enzymes needed for
the reaction
3) Light independent reaction occurs
here!
4) Light Independent reaction = Glucose
maker!
The Role of Pigments in Photosynthesis!
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Light is captured by PIGMENTS
The pigments can ABSORB or REFLECT
light
Leaves appear GREEN because green light
is REFLECTED to your eye.
What colour is a plant at night?
ROYGBIV  ROY & BIV are absorbed,
G is reflected
Photons
Photons – a packet of light energy
 Each photon corresponds to a small unit of
energy of a particular wavelength
 Photons with short wavelengths have high
energy and those with long wavelengths
have low energy
Do Questions #1 and 2 pg. 181
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Practice pg. 181
1.
2.
Name the three large groups of organisms
that carry out photosynthesis.
a) Define light.
b) What is a photon?
The Role of Chlorophyll
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Chlorophyll absorbs photons from solar
energy and begins the process of
photosynthesis
Chlorophyll a (blue-green) and chlorophyll
b (yellow-green) are the two most common
Chlorophyll a is the only pigment that can
transfer the energy from sunlight to the
reactions of photosynthesis. Chlorophyll b
acts as an accessory pigment, absorbing
photons that chlorophyll a absorbs poorly
or not at all.
 Carotenoids also act as accessory pigments
Do Questions 3-4 pg. 182

Practice pg. 182
3.
4.
What is the primary light absorbing
pigment in all photosynthetic organisms?
What colour(s) of the spectrum is absorbed
by chlorophyll a and chlorophyll b?
What colour(s) is transmitted by these
pigments?
3 Plant Pigments:
A) Chlorophyll (Appears GREEN)
* Absorbs ROY & BIV, Reflect or Transmits G
B) Carotene (Appears RED)
* Absorbs GBIV, Reflect or Transmits ROY
*** Green is the major pigment but fades in the fall to
reveal the lesser pigments  red, yellow and
brown (pg. 182)
Now What!
Textbook
questions:
Pg. 185 #1-3
Questions pg. 185
a) How are the wavelength and energy of a
photon related?
b) Which possesses a higher energy
value: red light or green light? Explain.
c) How is the color of light related to its
energy? Provide examples.
1.
Questions pg. 185 continued. . .
2. a) What pigments are present in green
leaves?
b) Explain why yellow-coloured pigments are
visible in autumn leaves but not in summer
leaves.
3. What do all photosynthetic organisms have
in common?
Label the diagram!
E- single
disc