Energy Relationships: Photosynthesis

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Energy RelationshipsPhotosynthesis

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Capturing light photons

• Pigments are molecules that absorb photons of
  light.
• 1)Main- Chlorophyll a absorb violet-blue-red
• 2)Accessory-
• Chlorophyll b violet-blue-red light
• Carotenoids green light
• Xantophylls yellow light

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• Pigments can only absorb certain wavelengths of
  light due to their structure
• Accessory pigments are necessary due to the fact
  that chlorophyll do not absorb wavelength in the
  range of 500-600 NM

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Importance of the Process

• Light is the initial energy source for almost all
  communities
• Most producers use sunlight to make complex
  nutrient compounds (carbohydrates)
• Plants do most of the planets photosynthesis but
  there are some photosynthetic bacteria
  (cyanobacteria)
• All other organisms in ecosystems are consumers
  (get energy by feeding on the tissues of
  producers or other consumers)

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The process

• Photosynthesis involves an energy conversion
• Hundreds of chemical change take place in the
  sequence but the overall reaction could be
  summarizes as
• CO2 H2O solar energy
  carbohydrate oxygen

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• Light energy is used to split H2O molecules
  (photolysis), producing O2 and H and releasing
  ATP
• ATP (adenosine triphosphate) and H are used to
  fix CO2 to make complex organic molecules

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Factors that affect photosynthetic rate

• CO2 concentration
• Light intensity
• Temeperature
• Students need to draw graphic representations

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• CO2 concentration
• Studies suggest that increasing CO2 increase
  photosynthetic rate, with the increased growth of
  producers removing more CO2 from the atmosphere
  thus slowing global warming
• Light intensity
• Normally, as light intensity increases,
  photosynthetic rate increases. The amount of
  light that penetrates the plant depend on several
  factors type of forest, type of crown, foliage
  density (leaf area index)

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• Temperature
• Temperature is associated with light intensity
  but producers have certain temperature tolerance
  (because of plant hormones)