Photosynthesis Chapter 8 Trophs Autotrophs Heterotrophs The Meaning

Photosynthesis Chapter 8

Trophs • Autotrophs • Heterotrophs

The Meaning of Life…

Photosynthesis 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 • 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 lightdependent 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 6 CO 2 + 6 H 2 O light C 6 H 12 O 6 + 6 O 2

O 2 + sugar CO 2 + H 2 O