8.2a Overview of Photosynthesis
Photosynthesis & Producers
Overview of
Photosynthesis
· producers (autotrophs)
use light energy from
the sun to produce their
own food
· photosynthesis =
process that captures
energy from sunlight to
make sugars that store
chemical energy
Section 8.2a
reveal answers
Photosynthesis
Pull
Light & Pigments
· chlorophyll (green pigment in chloroplasts) absorbs
some of the energy in visible light
What do plants
O2 breathe?
visible light (a.k.a. white light) = ROY G BIV
chlorophyll a and chlorophyll b absorb mainly red
and blue light
What doHplants
drink?
2O
· plants look green because they reflect green light
in the chlorophyll rather than absorb it
· light absorbed excites electrons (e-) in chlorophyll
· excited electrons run photosynthesis
sunlight
Do plants
need light?
Whatsugar;
do plants
C6H12make?
O6
What do plants
CO2 give off?
6CO2 + 6H2O
light, enzymes
Roy G BIV
C6H12O6 + 6O2
Photosynthesis & Chloroplasts
· membrane-bound organelle
· 2 main parts
grana
stacks of thylakoids
looks like a stack of coins
stroma
space/fluid surrounding grana
· photosynthesis occurs in 2 main stages
light-dependent reactions (light required)
occurs across thylakoid membrane
needs sunlight and water
light-independent reactions (NO light required)
occurs in stroma
uses energy fro the light-dependent reactions to
make sugars
8.2a Overview of Photosynthesis
Rate of Photosynthesis
· rate affected by light intensity and temperature
Review Questions
1. What is photosynthesis?
2. What is the chemical equation of photosynthesis?
3. Why are plants green?
4. Where does photosynthesis occur?
5. What are the two different series of reactions in
photosynthesis?
6. What two things affect the rate of photosynthesis?