Chapter 10 Photosynthesis

The Process That Feeds the Biosphere

10.1 Photosynthesis converts light energy to the chemical energy of food

Site of Photosynthesis

The Equation

Where does the oxygen come from?

Photosynthesis as a Redox Process Photosynthesis reverses the electron flow as compared to cellular respiration. The electrons increase in potential energy as they move from water to sugar. The energy for this is provided by light.

The Two Stages of Photosynthesis

The Nature of Sunlight

Photosynthetic Pigments

Spectrophotometer

Absorption vs Action Spectrum

Engelmann’s Experiment

Excitation of isolated chlorophyll molecules

How a photosystem harvests light

Linear electron flow

Cyclic Electron Flow

Light reactions

Calvin Cycle

Alternative mechanisms of carbon fixation C3 plants and photorespiration Consumes oxygen and releases carbon dioxide Uses ATP but does not generate sugars Occurs when stomata are partially closed on hot, dry days Rubisco has a greater affinity for oxygen than carbon dioxide

Photorespiration

C4 plants Preface Calvin Cycle with carbon fixation that forms a 4-carbon compound as its first product Ex) sugarcane, corn, and members of the grass family

C4 pathway

CAM Plants Cacti, pineapples Open stomata at night and close them during the day

CAM Pathway