Light & Photosynthesis or “You light up my life” A/H 100G J.G. Mexal

CO 2 capture Basic Photosynthetic Reaction CO 2 + H 2 O CH 2 O + O lb 0.60 lb 1.00 lb1.07 lb λ

Photosynthesis Action Spectra of Lights vs Chl a & b Absorption Incandescent light Cool white fluorescent light Chlorophyll A & B

Photosynthesis Light Compensation and Saturation Points Net Ps (mgCO 2 /cm 2 /h) Light Intensity (fc) C.P. S.P.

Photosynthesis Sun vs Shade Leaves Epidermis Palisade Mesophyll Spongy Mesophyll Epidermis Stomata Sun Shade

Photosynthesis Pathways for Photosynthesis C-3= most crops C-4= arid shrubs, grasses, pineapple CAM= succulents –(crassulacean acid metabolism)

Photosynthesis C 3, C 4, and CAM Plants

Photosynthesis Characteristics of C3 and C4 Plants

Photosynthesis Simplified C3 Pathway

Photosynthesis C3 Leaf Structure Palisade mesophyll Spongy mesophyll Epidermis Vein

Photosynthesis Light Compensation and Saturation Points

Photosynthesis Interaction between CO 2 and Light Intensity 1,300 ppm CO ppm CO ppm CO 2 Light Intensity Photosynthesis Rate

Photosynthesis Simplified C4 Pathway Spatial Separation

Photosynthesis Simplified C4 Pathway

Photosynthesis C4 Leaf Structure Bundle sheath cells Mesophyll Vein

Photosynthesis Distribution of C4 Plants/ Oecologia 23:1-12:1978 Percent of Grass Taxa Percent of Dicot Taxa

Photosynthesis C 3 & C 4 Response to Light Intensity Light Intensity Photosynthesis Sugarcane- C 4 Clover- C 3 Tobacco- C 3 Philodendron-C 3

Photosynthesis Simplified CAM Pathway 3-carbon compound Temporal Separation

Photosynthesis Simplified CAM Pathway

Photosynthesis What is this?????

Things to Know What happens to all the light striking the earth’s surface Light attributes –Quality –Quantity –Duration Plant pigments –Imp. Wavelengths –Actions Photoperiod response –Long-day –Short-day –Day-neutral –Important dates (why?) Ps Reaction –Basic –C 3, C 4, CAM

Quiz Questions Give the basic photosynthesis reaction and where does it take place? Describe the characteristics of C-3 and C-4 plants. Give examples of a C-3 and C-4 plant. Describe the differences between a C-4 and CAM plant. Give an example of a CAM plant. What is a ‘short-day plant’? ‘long-day plant’? ‘day-neutral plant’? How do plant ‘tell time’? What’s the reaction? Why do C-4 plants have a higher rate of photosynthesis. Describe leaf morphology of both.

Light and Photobiology Electromagnetic Spectrum Energy (kcal/cm Wavelength (nm)

Photosynthesis Leaf Tissues & Function Tissue –Epidermis –Guard cells & stomates –Chlorophyll- containing cells –Veins Primary Functions –Protective cells (keep water within leaf) –Allow CO 2 & O 2 diffusion for Ps & Rs –Manufacture ATP & glucose –Translocate H2O and nutrient to, and CHO & AA away from, the leaves