How do Autotrophs Produce their own Food?

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How do Autotrophs Produce their own Food?

• Chemosynthesis chemical energy sources (ex. H2S)
• Ex., producers in deep-sea vent communities are
  chemosynthetic bacteria (animals still dependent
  on oxygen from photosynthesis)
• Photosynthesis 6CO2 12H2O ? C6H12O6 (glucose)
  6O2 6H2O
• For plants, occurs in chloroplasts (mainly in
  leaves) need sunlight and light-sensitive
  pigments (ex. chlorophyll)
• Light-dependent reactions (occur in thylakoids of
  chloroplast)
• Capture of light pigments absorb photons color
  you see is reflected part of spectrum (blue and
  yellow with chlorophyll)
• Water is split (photolysis), releasing oxygen
  gas, electrons
• Electron transport reactions and chemiosmosis
  production of ATP, NADPH
• Light-independent reactions (Calvin cycle)
• Formation of glucose in step-wise fashion from
  CO2, using the energy gained from the
  light-dependent reactions
• Carbon fixation CO2 molecules joined (involves
  enzyme, rubisco)
• Carbon reduction hydrogen atoms added, oxygen
  atoms removed
• Glucose is used for cell respiration, or
  converted to starch or cellulose
• Variations of metabolic pathways c3, c4, CAM
  plants

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Figure 10.2
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Figure 10.4
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Figure 10.5
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Figures 10.6
and 10.9
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Figures 10.10 and 10.11a
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Figure 10.12
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Figure 10.13
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Figure 10.16
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Figure 10.17
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Figure 10.18
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Figure 10.21
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What are C4 and CAM Plants?

• C3 Plants and Photorespiration in C3 plants (ex.
  rice, wheat, soybeans), when CO2 is low, rubisco
  adds O2 to the Calvin Cycle, reducing sugar
  yield
• Considered a byproduct of the fact that C3
  photosynthesis evolved when oxygen levels were
  relatively low
• C4 Plants (ex. sugarcane, corn) produce a
  four-carbon compound in mesophyll cells, release
  CO2 molecules to Calvin Cycle in adjacent
  bundle-sheath cells enzyme in mesophyll cells
  (PEP carboxylase) has no affinity for O2
• CAM Plants (ex. cacti, pineapples) carbon
  incorporated into organic acids at night, which
  release CO2 to the Calvin Cycle in the day (when
  stomata closed)

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Figure 10.19
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Figure 10.20