Download Photosynthesis

Photosynthesis
Ch.2 Sec. 1
The Process
• 2 steps
• Happens in the chloroplasts
• Mostly in the leaves of
plants
Step 1: Capture Energy
• Chloroplasts contain
chlorophyll
– Green pigment
• Chlorophyll absorbs solar
energy
– Like a solar panel
Step 2: Make Food
• Use energy from Step 1
• Also need water and CO2
• Water comes from soil
– Travels up from roots
• CO2 comes from air
– Enters through stomata
Stomata
• Small openings on the
bottoms sides of leaves
• Allow O2 and water out
• Allow CO2 in
• Can open and close as
needed
Stomata
•
Step 2 (cont’d)
• The energy from Step 1 is
used to take apart the CO2
and H2O and recombine
them as glucose (C6H12O6)
• O2 is produced as a
byproduct
The equation
CO2 + H2O
Light energy
C6H12O6 + O2
The equation
CO2 + H2O
Light energy
C6H12O6 + O2
Balanced:
6CO2 + 6H2O
Light energy
C6H12O6 + 6O2
The products
• Sugar – glucose
– Used as food for energy
– Combined into starches to
make cell walls = cellulose
– Stored for later – become
part of plant
The products
• Oxygen
– Passes out through stomata
– Some used to break down
sugar in mitochondria
The circle of life
• Plants and other organisms
that do photosynthesis =
autotrophs
• Organisms that can’t make
their own food =
heterotrophs
The circle of life
• Heterotrophs get their
energy
– by eating autotrophs
• Break down the stored sugar
– By eating heterotrophs that
have eaten autotrophs
The circle of life
• All living things ultimately
get their energy from the
sun
• Food chain/web
Sunautotrophsheterotro
phsother heterotrophs