1. Light and Photosynthesis

2. Light Light is the most familiar form of electromagnetic radiation –Electromagnetic radiation is energy that is moving in the form of waves (so has all the characteristics of waves) Examples: x-rays, radio waves, infrared, gamma rays, etc. –The visible spectrum is the range of wavelengths that our eyes can see R O Y G B I V INFRARED ULTRAVIOLET

3. Long wavelength (λ) Short λ RED ~680 nmViolet ~400 nm less energy more energy Of the light that leaves the sun ~50% is absorbed or reflected by the Earth’s atmosphere (ozone absorbs UV) –Of the remaining 50% approximately 65% of that is absorbed within one meter of water Because light is absorbed quickly in water, photosynthesis is limited to the upper 100 meters Even under the best circumstances only 1% of light reaches 100 meters

4. Absorption of Light by Ocean Water Red 5-10m Orange10-15m Violet 10-30m Yellow15-25m Green30-50m Blue50-100m

5. Turbidity is the amount of cloudiness of the water and effects the depth at which light can penetrate. In an area with high turbidity (ex. coastal area with run-off) light is not able to penetrate as deep. The lowest depth at which phytoplankton (microscopic algae) can survive is the COMPENSATION DEPTH Photosynthesis (production of glucose/energy) = Cellular Respiration (consumption of glucose/energy)

6. Photosynthesis 6 H 2 O + 6 CO 2 C 6 H 12 O 6 + 6 O 2 WATERCARBON DIOXIDEGLUCOSEOXYGEN Cellular Respiration C 6 H 12 O 6 + 6 O 2 6 H 2 O + 6 CO 2 + ATP ATP=Adenosine Tri-phosphate Requirements for Photosynthesis –Light (energy) –Water –Carbon Dioxide –Pigments (like chlorophyll) to absorb light energy

7. Because different wavelengths of light descend to different depths before they are absorbed, algae may have different pigments (or different amounts/ratios of pigments) to capture the light. –Chlorophyll (a and b) – absorbs red/orange and violet but reflects green –Xanthophyll – absorbs green very well –Fucoxanthin –Carotene – reflects orange –Phycoerythrins – absorb blue light (which penetrates deepest) allowing algae with this pigment to exist in deeper water