Warm Up Monday
November 19th
List 5 common household
items that you use everyday
that come from plants.
PHOTOSYNTHESIS
The Sun
the ultimate source of all
energy for all life on Earth
Autotrophs Vs. Heterotrophs
An autotroph is an organism that feeds itself!
(produces its own food!)
A heterotroph is an organism that feeds on
another organism (cannot produce own
food!)
Can you think of an example of each?
Poison Sumac
Lions (and Zebras for that matter!)
Autotroph or Heterotroph?
Autotroph or Heterotroph?
Autotroph or Heterotroph?
Autotroph or Heterotroph?
Autotroph or Heterotroph?
Photoautotrophs
Photo = Light
Auto = Self
Troph = Feed
Plants are “photoautotrophs”
because they feed
themselves with light.
PHOTOSYNTHESIS
…is the conversion of light
energy into chemical energy by
living organisms
Prickly Pear Cactus
Cedar Tree
Why should I
care about
photosynthesis?
More than 200 years ago, Priestly
stumbled upon the answer!
Who? Me?
NO! ME!!!
Joseph Priestly
1733-1804
Photosynthesis
overview
What Light is Available
for Plants to use?
Light acts as both a
particle (photon) and
a wave!
The different lengths
of light waves create
the spectrum of colors
we can see!
Red = LONG waves
Violet = SHORT waves
How do plants absorb
light?
Pigments in the chloroplast absorb a
variety of light energy wavelengths.
Examples:
Chlorophyll A & B
Xanthophyll
Carotenoids
Chlorophyll a
Found in all plants, algae and
cyanobacteria.
 Makes photosynthesis possible.
 Participates directly in light reactions
 Can accept energy from chlorophyll b

Chlorophyll b
Is an accessory pigment
 Chlorophyll b acts indirectly in
photosynthesis by transferring the light
it absorbs to chlorophyll a

Plant Pigments
Seen w/ Paper Chromatography
Absorption Spectrum
Plants only absorb violet and red light,
and reflect green light, which
is why plants appear green!
Where does
Photosynthesis happen?
In Chloroplasts!
What’s in a Chloroplast?
Photosynthesis takes place
within the thylakoid membranes!
Light Reactions
Light Reactions
First step in photosynthesis
where light energy is
converted to chemical energy.
Light energy is used to break
apart H2O into H2 & O2.
Light Reactions
The H+ ions and the free
electrons that result from
breaking apart water make
high energy molecules!
ATP & NADPH
The Calvin Cycle
A set of reactions that turn CO2 into Carbon
assembled into glucose.
CO2  Sugars
The Calvin Cycle requires energy from ATP
& NADPH made by Light Reactions!
aka “Dark Reactions” b/c doesn’t need light
Dark Reactions
(calvin cycle)
Chemical reactions that convert
CO2 and other compounds into
Glucose!
Doesn’t require light energy.
Takes place in the space outside
the thylakoid membrane.
Photosynthesis