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Photosynthesis Using Light to Make Food

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Using Light to Make Food Photosynthesis : Why Study It? Most Important biological process on earth Fills food requirements & needs for fiber & building material ... – PowerPoint PPT presentation

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Title: Photosynthesis Using Light to Make Food


1
PhotosynthesisUsing Light to Make Food
2
Photosynthesis Why Study It?
  • Most Important biological process on earth
  • Fills food requirements needs for fiber
    building material
  • Petroleum, natural gas, coal, firewood

3
Photosynthesis
  • Three major events
  • Absorption of light energy
  • Conversion of light energy into chemical energy
    (ATP and NADPH)
  • Storage of potential energy in carbohydrates
  • Photo
  • Means Light
  • Synthesis
  • Means to Make

4
Spectrum of Light Energy
Spectrum of light energy - Photosynthesis uses
only a small portion of this spectrum of light
energy.
5
Where does it happen?
  • Green tissues of plants
  • Mostly in the leaves, but not always
  • Cells of green tissues have chloroplasts which
    contain
  • Thylakoids (pan-cake)
  • Chlorophyll found here
  • Grana (stacks)
  • Light reactions occur here
  • Stroma (thick fluid)
  • Carbon Fixation
  • Uses carbon from CO2 to make carbohydrates
  • Dark reactions occur here

6
Two Stages
  • Light-Dependent Reactions
  • Temperature independent
  • (Light Reactions)
  • Temperature-Dependent Reactions
  • Light independent
  • (Dark Reactions)

7
Light Reactions
  • Requires direct energy of light to make carrier
    molecule needed for Stage 2
  • Occurs in the Grana
  • Absorption of light by pigments
  • Light energy is converted into chemical energy
  • Three products formed
  • Oxygen gas
  • ATP
  • NADPH (hydrogen carrier)

8
Dark Reactions
  • Occurs in Stroma
  • Requires energy carriers from light reactions
    (ATP, NADPH)
  • Calvin Cycle
  • Incorporates carbons into carbohydrates

Carbon Fixation
9
The Equation
6CO2 6H20 Light energy
----gt
C6H12O6 6 02
How does this equation compare to cellular
respiration?
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