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10/24/2011
Producers and Consumers
Autotrophs (self-feeders):
•Make their own organic matter
from inorganic nutrients.
Heterotrophs (other-feeders):
(other feeders):
•Organisms that cannot make
organic molecules from inorganic
ones.
Energy Flow and Chemical Cycling
in the Biosphere
Sunlight energy
enters ecosystem
C6H12O6
(Glucose)
+
O2
(Oxygen)
CO2
(Carbon
dioxide)
+
H2O
(water)
Photosynthesis
Cellular respiration
ATP drives cellular work
Heat energy exits ecosystem
Photosynthesis
Photosynthesis:
• Is used by plants, some protists, and some bacteria
• Transforms light energy into chemical energy
• Uses carbon dioxide and water as starting materials
Light
energy
6 CO2
6 H2O
Carbon
dioxide
Water
C6H12O6
Photosynthesis
Glucose
6 O2
Oxygen gas
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Photosynthesis
– Organisms that use photosynthesis are:
• Photosynthetic autotrophs
• The producers for most ecosystems
PHOTOSYNTHETIC AUTOTROPHS
Photosynthetic Protists
(aquatic)
Photosynthetic Bacteria
(aquatic)
LM
Plants
(mostly on land)
Forest plants
Kelp, a large alga
Micrograph of cyanobacteria
Photosynthesis
found b/w
lower and upper
epidermis
Photosynthesis
CO2
H 2O
Light
Chloroplast
NADP+
ADP
P
Light
reactions
Calvin
cycle
ATP
NADPH
O2
Sugar
(C6H12O6)
2
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Photosynthesis
*photon
*Photons are
absorbed by
pigment molecules
Why Green?
Light
Reflected
light
Chloroplast
Absorbed
light
Transmitted
light
Light-harvesting complexes of the thylakoid membrane
3
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Electron Flow
Organization of light reaction machinery
Chemiosmosis: A Comparison
4
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Calvin cycle (Carbon Fixation)
Photosynthesis
Alternative
Pathways
ALTERNATIVE PHOTOSYNTHETIC PATHWAYS
CAM Pathway
C4 Pathway
(example: sugarcane) (example: pineapple)
Cell
type 1
CO2
Four-carbon
compound
Cell
type 2
CO2
Night
Four-carbon
compound
CO2
CO2
Calvin
cycle
Calvin
cycle
Sugar
C4 plant
Day
Sugar
CAM plant
5