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Photosynthesis
Photosynthesis
The process where light energy is
converted into chemical energy
Photosynthesis
• Autotrophs change light
energy into chemical energy
in the process of
photosynthesis.
• Plants use light energy to
convert water and carbon
dioxide into oxygen and
carbohydrates (sugars and
starches)
Process of Photosynthesis
• Photosynthesis is a
process used by green
plants
• The is a type of
autotrophic nutrition.
• Photosynthesis is
carried out by
chloroplasts, which
contain chlorophyll
• In the chloroplasts,
CO2 and H2O are used
to form C6H12O6 and
O2
Process of Photosynthesis
6 CO2 + 6 H2O
C6H12O6 + 6 O2
= light energy
trapped in the
chloroplast makes
this process
happen
Process of Photosynthesis
Photosynthesis Equation
6CO2 + 6H2O
carbon
water
C6H12O6 + 6O2
light energy
dioxide
sugar
oxygen
(glucose)
• Requirements:
– 6CO2 – carbon dioxide
is absorbed from the
environment
– 6H2O – water
absorbed from the
environment
– Energy – energy from
the sun is trapped by
the chlorophyll in the
chloroplasts
• Products/Wastes:
– C6H12O6 – organic
sugar (glucose) is
stored in the plant
– 6O2 – oxygen is
released as a waste
product
Factors Affecting Photosynthesis
• Water or Carbon dioxide (wax prevent water loss)
• Temperature (0-35°C for enzymes)
• Light intensity (min and max)
or water
Adaptations for Photosynthesis
• Autotrophic algae
carries out
photosynthesis
• They are responsible
for the large
percentage of oxygen
found on the Earth (in
water)
Adaptations for Photosynthesis
• Terrestrial plants are
complex organisms
also adapted for
photosynthesis
• Photosynthesis may
occur in the stems of
some plants
• Leaves are best
adapted for the
process of
photosynthesis
http://earthguide.ucsd.edu/earthguide/diagra
ms/photosynthesis/photosynthesis.html
Stomata
• Pore-like opening on the bottom of plant leaf
that allows carbon dioxide to diffuse in or
oxygen to diffuse out.
Light and Pigments
• Energy from the sun travels to Earth in the
form of light of different wavelengths of the
visible spectrum as different colors
• Plants gather the sun’s energy with lightabsorbing molecules called pigments.
Chloroplasts
• Chlorophyll in the
chloroplast is the green
pigment that captures light
energy.
• Oxygen is released through
the leaves
• Organic sugars made are
used by the autotroph to
grow/develop or stored as
carbohydrates or lipids.
Photosynthesis: Reactants and
Products
Section 8-2
Light Energy
Chloroplast
CO2 + H2O
Go to
Section:
Sugars + O2
Green Plants
• Chlorophyll absorbs light in the red and blue regions
of the visible spectrum, but does not absorb light in
the green region.
• Green light is reflected making plants appear green!
• Plants also contain red and orange pigments (ex.
Carotene) that absorb light in other regions of the
spectrum.
• Any compound that absorbs light absorbs energy
from that light and transferred it directly to electrons
in the pigment molecules, raising the energy level of
the electrons.
Figure 8-5 Chlorophyll Light
Absorption
Section 8-2
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a
V
Go to
Section:
B
G
YO
R