Cell Biology
8.2 What is photosynthesis?
In photosynthesis, plants
take in carbon dioxide
and water and release
glucose and oxygen
wastes.
•  Photosynthesis is a
chemical reaction that
takes place in the
chloroplasts of plant
cells.
•  During photosynthesis,
plants use the energy of
sunlight to produce
energy-rich molecules
called carbohydrates
(ex. glucose).
8.2 What is photosynthesis?
•  Chloroplasts are
where photosynthesis
occurs.
•  Chloroplasts work
much like solar cells
found in calculators.
8.2 Light and color
•  The Sun provides
Earth with a steady
source of light.
•  Your eyes see sunlight
as white light, but it is
really made up of
different colors of light.
A clear prism can split white
light into a rainbow of color.
8.2 Light and color
•  Light is part of a collection of waves known as
the electromagnetic spectrum.
•  Waves can be described by their wavelength
(length from peak to peak), and their energy.
8.2 Light and color
•  Color is how we experience the energy of
light.
8.2 Chlorophyll
•  A pigment is a
molecule that
absorbs some
colors of light and
reflects others.
•  Chlorophyll is the
main pigment used
in photosynthesis.
8.2 Chlorophyll
•  Chlorophyll
absorbs mostly
blue and red
light, and reflects
green light.
•  This is why most
plants look green.
8.2 Cellular respiration
•  Cellular respiration
is a chemical reaction
that occurs in all
living things.
•  Cells use oxygen and
glucose to produce
carbon dioxide,
water, and energy.
8.2 Cellular respiration
•  In most eukaryotic
organisms, cellular
respiration takes place in
the mitochondria of cells.
•  During cellular respiration,
energy is stored in a
molecule called ATP while
some energy is released as
heat.
8.2 Comparing photosynthesis
and respiration
•  The chemical equations of photosynthesis
and respiration have an interesting
relationship.
•  The reactants in photosynthesis are the
products in cellular respiration!
•  The reactants in cellular respiration are
the products in photosynthesis!
Research
Connection
Amazing Cells
•  So how do stem
cells change into
other types of cells?
•  Scientists are
studying the answer
to this question.