Chapter 10 Photosynthesis

Photosynthesis

Ps General Equation Requires:

Question u Does the Oxygen in sugar come from the CO 2 or from the H 2 O ? u Model: CO H 2 O ----> CH 2 O + O 2

Proof u Used 18 O as a tracer. CO H 2 O ----> CH 2 O + O 2

Ps: a redox process

Ps

Light

Too Hot Too Cold Just Right

Action Spectrum

Comment u In oceans, red light is lost or filtered out early because it has lower energy. u Only blue light which has higher energy can reach the lower depths.

Result u Many deep ocean fish are bright red in color. u Why? u They can’t be seen because there is no red light to reflect their color.

Photosynthesis Pigments

Chlorophylls

Accessory Pigments

Fall Leaf Colors

Chloroplast Structure

Photosystems

Cyclic Photophosphorylation

Noncyclic Photophsphorylation

Light Reaction

u Location – u Function

Light Reaction RequirementsProducts

Chemiosmosis Model

Chemiosmosis

Comment u There can be a 3 pH unit difference between the thylakoid space and the stroma.

Movie - Summary

Dark Reactions

Dark Reaction

Rubisco

C3 Ps RequirementsProducts

Photorespiration

Alternate Ps Methods 1. C4 Ps 2. CAM Ps

C4 Ps

PEP Carboxylase

C4 Ps

C3 Ps vs C4 Ps Photorespiration Shade to full sun High water use Cool temperatures Slow to moderate growth rates Cool season crops No Photorespiration Full sun only Moderate water use Warm temperatures Very fast growth rates Warm season crops

CAM Ps

CAM plants

Ps:Rs Ratios u Reflect a plant’s balance in making food and using food. 1. Ps > Rs, energy available for growth and reproduction. 2. Ps = Rs, no growth, but don’t die either. 3. Ps < Rs, death by starvation

Comments - Ps:Rs

Factors That Affect Ps 1

Importances of Ps

Summary u Know the main Ps equation. u Know Light Reaction. u Know Dark Reaction. u Alternate Ps forms. u Ps:Rs ratios.