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Photosynthesis

Photosynthesis. Photosynthesis: History and Overview. Photosynthesis. Is The Use Of The Energy In Sunlight To Convert Water (H 2 0) and Carbon Dioxide (CO 2 ) Into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches. Investigating Photosynthesis. Key Concept :

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Photosynthesis

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  1. Photosynthesis Photosynthesis:History and Overview

  2. Photosynthesis Is The Use Of The Energy In Sunlight To Convert Water (H20) and Carbon Dioxide (CO2)IntoOxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

  3. Investigating Photosynthesis Key Concept: Many Scientists Have Contributed To Understanding Photosynthesis. Early Research Focused On The Overall Process. Later Researchers Investigated The Detailed Chemical Pathways

  4. Investigating Photosynthesis Several Centuries Ago,The Question Was:Where Does A PlantsMassCome From? Air? Water? Soil?

  5. Van Helmont’s Experiment 1643 • Planted A Seed Into A Pre-weighed Amount Of Soil. Added Water For 5 Years. • Weighed Plant & Soil. Plant Was 75 kg, Soil weight unchanged. Concluded Mass Came From Water

  6. Priestley’s Experiment 1771 • Burned Candle In Bell Jar Until It Went Out. • Placed Sprig Of Mint In Bell Jar For A Few Days. • Candle Could Be Relit And Burn. • Concluded Plants Released Substance Necessary For Combustion.

  7. Ingenhousz’s Experiment 1779

  8. Ingenhousz’s Experiment 1779 • Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight. • Light Was Necessary For Plants To Produce The “Burning Gas”

  9. Julius Robert Mayer 1845 Proposed That Plants Convert Light Energy Into Chemical Energy

  10. Samuel Ruben & Martin Kamen1941 Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water

  11. Melvin Calvin 1948 Traces The Path Carbon Follows To Produce Glucose. Did Not Require Sunlight Calvin Cycle AKA Light Independent ReactionAKA Dark Reaction

  12. Rudolph Marcus 1992 Describes The Chemistry Of The Light Dependent Reactions, Including The Electron Transport Chain

  13. The Photosynthesis Equation Carbon Dioxide + WaterIn The Presence Of LightReacts To FormSugar + Oxygen

  14. The Photosynthesis Equation 6CO2 + 6H2O C6H12O6 + 6O2 Light

  15. Light & Pigments Key Concept: • In Addition To Water And Carbon Dioxide, Photosynthesis Requires Light And Chlorophyll. • Chlorophyll Is Contained In Chloroplasts

  16. Light & Pigments • Energy From The Sun Enters Earth’s Biosphere As Photons Photon = Light Energy Unit • Light Contains A Mixture Of Wavelengths Different Wavelengths Have Different Colors

  17. Light & Pigments

  18. Light & Pigments • Plants Gather Suns Energy By Absorbing The Energy Into Pigments. • Pigments = Light Absorbing Molecules Plants Principal Pigment = Chlorophyll

  19. Light & Pigments Chlorophyll 2 Types Chlorophyll a Chlorophyll b

  20. Chlorophyll a & b

  21. Light & Pigments Chlorophyll a • Blue-Green • Participates Directly In The Light Reactions • Can Accept Energy From Chlorophyll b

  22. Light & Pigments Chlorophyll b • Yellow-Green • Does NOT Directly Participate In The Light Reaction

  23. Light & Pigments • Chlorophyll Absorbs Light Very Well In The Blue & Red Regions Of The Spectrum • It Does NOT Absorb Well In The Green • Absorbed Energy Is Transferred To Electrons In Chlorophyll

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