Photosynthesis
&
Cellular Respiration
Autotrophs & Heterotrophs
• An organism that makes
its own food is called an
autotroph.
• An organism that cannot
make its own food is
called a heterotroph.
• Nearly all living things get
their energy directly or
indirectly from
photosynthesis.
Photosynthesis
• The process by which
a cell captures energy
in sunlight and uses it
to make food.
• The raw ingredients
that go into the plant
cells are water and
carbon dioxide
• The sunlight energy
chemically changes
the ingredients into
food (glucose)
CO2
Photosynthesis
• Water is absorbed by
the roots.
• Carbon dioxide gas is
taken from the air
• Glucose is stored and
used by the plant
• Oxygen is released
into the air
The chemical formula for
photosynthesis looks like this:
Energy
6H2O + 6CO2
(water)
(carbon dioxide)
(Sunlight)
C6H12O6 + 6O2
(glucose)
(oxygen)
O2
CO2
Photosynthesis occurs in the
chloroplasts of plant cells.
Chlorophyll is the
energy absorbing green
pigment found in
chloroplasts.
Gas Exchange
• Gasses (CO2 & O2) go in
and out of leaves through
little holes called
stomata.
• Sometimes water vapor
escapes the stomata
through a process called
transpiration.
Guard cells control when the stomata
open and close.
Guard Cells
Since leaves can lose water through
stomata, on what part of the leaves
do you think stomata can be found?
 Make a prediction.
Stomata are mostly found on the underside of
leaves. This helps the plant lose less water.
Cellular Respiration
• The process by which
cells obtain energy from
glucose.
• Respiration means
“breathing”
• This chemical reaction
takes place in the matrix
of the mitochondria
Cellular Respiration
Glucose chemically reacts with Oxygen to
form the energy molecule ATP
C6H12O6 (glucose)
ATP (energy)
H2O (water)
O2 (oxygen)
CO2(Carbon dioxide)
The chemical formula for cellular
respiration looks like this:
C6H12O6 + 6O2
(glucose)
Energy
(ATP)
(oxygen)
+ 6H2O + 6CO2
(water)
(carbon
dioxide)
Does this look familiar?
6H2O + 6CO2
+ Energy
(water) (carbon dioxide)
(Sunlight)
C6H12O6 + 6O2
(glucose)
(oxygen)
The Cycle of
Cellular Energy
in Plants
• The products
made by the
chloroplasts are used
by the mitochondria.
• The products
made by the
chloroplasts are used
by the chloroplast.
Why don’t animal cells
have this cycle?
Fermentation provides energy for
cells without using oxygen.
• Deep water organisms
• Yeast (alcohol is byproduct)
• Muscle Cells (lactic acid is a
byproduct = sore muscles)