ch 8: photosynthesis

• Photosynthesis


  Process converting solar energy to chemical energy
• CO2


  Waste product in photosynthesis
• Autotrophs


  Organisms producing organic molecules from inorganic sources
• Heterotrophs


  Organisms consuming organic material from others organisms and are consumers of the biosphere
• Leaves


  Major sites of photosynthesis in plants
• Chlorophyll


  Pigment absorbing light energy in photosynthesis
• Stomata


  Microscopic pores allowing CO2 entry and O2 exit in leaves
• Jan Baptist van Helmont

  Conducted 1600's experiment on plant growth from water
• Light reactions


  Photosynthesis stage in thylakoids splitting H2O, releasing O2, ReducingNADP+to NADPH, and Generating ATP from ADP byphotophosphorylation
• Calvin cycle

  Photosynthesis stage in stroma forming sugar from CO2 using ATP and NADPHbegins withcarbon fixation, incorporating CO2 into organic molecules
• Electromagnetic radiation


  Form of light energy traveling in waves
• Pigments

  Substances in leaves absorbing visible light· Different pigments absorb different wavelengths· Wavelengths that are not absorbed are reflected or transmittedLeaves appear green because chlorophyll reflects green light
• Photon


  Discrete particle of light energy
• Absorption spectrum

  Graph showing pigment's light absorption vs. wavelength
• Chlorophyll a


  Primary photosynthetic pigment absorbing violet-blue and red light
• Accessory pigments


  Pigments broadening light spectrum for photosynthesis
• Chemiosmosis


  Process generating ATP in organelles using energy sources
• Rubisco


  Enzyme catalyzing carbon fixation in the Calvin cycle
• Glyceraldehyde-3-phosphate (G3P)


  Sugar produced in Calvin cycle from CO2
• Starch


  Excess sugar stored in plants for energy