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8.2 Photosynthesis: An Overview

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8.2 Photosynthesis: An Overview Photosynthesis - The process by which plants use the energy from sunlight to convert water and carbon dioxide into high energy ... – PowerPoint PPT presentation

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Title: 8.2 Photosynthesis: An Overview


1
8.2 Photosynthesis An Overview
2
Photosynthesis
  • - The process by which plants use the energy from
    sunlight to convert water and carbon dioxide into
    high energy carbohydrates, oxygen.
  • The formula
  • 6H2O 6CO2 ? C6H12O6 6O2

3
Photosynthesis History
  • Van Helmont (1643)
  • Devised an experiment that led him to conclude
  • That a tree gains most of its mass from water
  • J. Priestley (1771)
  • Using a bell jar, candle, and a plant he
    concluded
  • The plant releases oxygen

4
  • J. Ingenhousz (1779)
  • Found that aquatic plants release bubble of
    oxygen in the light but not in the dark
    concluding
  • Plants need sunlight to produce oxygen
  • The above scientists, led others to discover that
    in the presence of light, plants transform carbon
    dioxide into carbohydrates and they also release
    oxygen.

5
The Photosynthesis Equation
  • 6H2O 6CO2 ? C6H12O6 6O2
  • Photosynthesis is a series of reactions that use
    light energy from the sun to convert water and
    carbon dioxide into sugars and oxygen.

6
Lights and Pigments
  • In addition to water and carbon dioxide,
    photosynthesis requires light and chlorophyll, a
    molecule in chloroplasts.
  • Cliff notes on light
  • White all color wavelengths being reflected
    back at you.
  • Black all color wavelengths being absorbed and
    none being reflected back at you.
  • The color you see is not absorbed but is reflected

7
Lights and Pigments
  • Pigment light absorbing molecules
  • Chlorophyll plants primary pigment
  • Chlorphyll a
  • Chlorophyll b
  • When plants absorb light, the energy is
    transferred directly to electrons in the
    chlorophyll, powering photosynthesis.

8
Section Assessment
  • 1.  Key Concept What did van Helmont, Priestley,
    and Ingenhousz discover about plants?
  • 2.  Key Concept Describe the process of
    photosynthesis, including the reactants and
    products.
  • 3.  Key Concept Why are light and chlorophyll
    needed for photosynthesis?
  • 4. Describe the relationship between chlorophyll
    and the color of plants.
  • 5. Critical Thinking Predicting How well would a
    plant grow under pure yellow light? Explain your
    answer.
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