Photosynthesis Chapter 8

Trophs Autotrophs Heterotrophs

The Meaning of Life…

Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen. Green things are generally understood to be photosynthesizers

Chlorophyll Chlorophyll a Chlorophyll b Pigments that absorb varying frequencies of light. Poor absorbers of blue-green frequency

Chloroplasts Thylakoids- contain photosystems which are the light-collecting units Sunlight excites electrons in the chlorophyll which are then passed to electron carriers (Sound familiar?) NADP+ is charged with an electron to form NADPH

Light Dependent Reactions

Light Dependence Two reactions are considered light-dependent in photosynthesis Photosystem II absorbs light and produces energized electrons, H+ ions, and water. Photosystem I receives tired electrons from II, are re-energized by sunlight, and used to make NADPH which passes to Calvin.

Mr. Calvin ATP and NADPH from the light-dependent reactions are used by the Calvin Cycle to create sugars.

Factors Affecting Photosynthesis Water availability Sunlight intensity Temperature (photosynthetic enzymes function best from 0-35 degrees C) Light Wavelength

Back and Forth light 6CO2 + 6H2O C6H12O6 + 6O2

O2 + sugar CO2 + H2O