Chapter 3, Section 3
 The process by which a cell captures energy in
sunlight and uses it to make food is called
photosynthesis. Photo means “light” and
synthesis means “put together”.
 Nearly all living things obtain energy either
directly or indirectly from the energy of
sunlight captured during photosynthesis.
 Grass
receives energy directly
from the sun.
 The cow receives energy
indirectly from eating the
grass.
 The owl receives energy
indirectly from eating the
mouse.


Plants manufacture
their own food
through the process of
photosynthesis.
An organism that
makes its own food is
called an autotroph.
 An
organism
that
CANNOT
make its own
food is called a
heterotroph.


Many heterotrophs
obtain food from
eating other
organisms.
Some heterotrophs,
such as fungi, absorb
their food from other
organisms.
 During
photosynthesis
plants and some other
organisms use energy from
the sun to convert carbon
dioxide and water into
oxygen and sugars.


Stage 1 involves capturing the energy in
sunlight.
In plants, the energy capturing mostly occurs
in the leaves.
The organelles called chloroplasts
contain a green pigment, chlorophyll.


Chlorophyll captures light energy to power
the second stage of photosynthesis.




Now, the cell uses the “captured”
energy to produce sugars.
It takes two raw materials, water (H20)
and carbon dioxide (C02).
In plants water is absorbed from the
roots through the stem to the leaves.
Carbon dioxide enters through tiny
openings or pores on the underside of
the leaves called stomata.
Inside the chloroplasts, the water and
carbon dioxide go through a series of
chemical reactions!
 The reactions are powered by the energy
“captured” in stage 1.
 These chemical reactions produce
new products.
 One product is SUGAR that has
six carbon atoms.



The other product of photosynthesis
is OXYGEN (O2).
Oxygen leaves through the same
stomata on the leaf of the plants.

Almost all the
oxygen on the
planet is
produced by
living things
through
photosynthesis.
6C02 + 6H20
carbon
dioxide
water
light energy
>>>>>>>>>>
(chemical reaction)
C6H1206 + 6 02
a sugar
oxygen
Use pages 88-89 to draw a leaf and show photosynthesis below: