Photosynthesis

• What is the overall equation for photosynthesis?

  6 carbon dioxide + 6 water -----> Glucose + 6 oxygen
• What role does carbon dioxide play in the Calvin cycle?

  Carbon dioxide is used in the Calvin cycle
• What is the purpose of water in photosynthesis?

  Water is used in photolysis
• What is produced in the Calvin cycle?

  Glucose is made in the Calvin cycle
• What is produced through photolysis?

  Oxygen is made through photolysis
• What are the two main stages of photosynthesis?

  1. Light dependent - occurs in the thylakoid membrane
  2. Light independent - occurs in the stroma
• What happens to light energy during photosynthesis?

  Light energy is transferred to chemical energy in carbon compounds
• How is hydrogen obtained for glucose production?

  Hydrogen is obtained from water to convert carbon dioxide to glucose
• What is photolysis?

  Photolysis is the splitting of water by the energy of photons from light
• What is thin layer chromatography used for?

  • It uses a thin layer of absorbent such as silica gel
  • The mixture travels faster and separates more distinctly
• What are the similarities and differences between absorption and photosynthetic action spectra?

  Similarities:

  • Peaks for blue and red
  • Green has the lowest levels

  
  

  Differences:

  • Rate of photosynthesis for green is higher than the light absorbed due to accessory pigments
• What do enclosed greenhouses and FACE experiments investigate?

  • Effects of increased carbon dioxide
  • Enclosed greenhouses artificially increase levels
  • FACE investigates elevated carbon dioxide in natural ecosystems
• How is the structure of chloroplasts adapted to their function?

  • Thylakoids have a small internal volume to maximize the hydrogen gradient
  • Many grana increase surface area
  • Grana contains photosynthetic pigments
  • Chlorophyll is arranged into photosystems to maximize light absorption
  • Stroma has suitable pH and enzymes for the Calvin cycle
  • Lamellae connect grana to maximize photosynthetic efficiency
• What are photosystems?

  Photosystems are arrays of pigment molecules that can generate and emit excited electrons
• What occurs during photoactivation?

  Light hits the system, is absorbed, and sends the electron to a higher energy level
• What are the steps of the light dependent reaction?

  1. Chlorophyll in photosystem II absorbs light, producing an excited electron
  2. Photophosphorylation occurs, electrons pass along the ETC
  3. Protons are pumped into the thylakoid space
  4. ATP is produced through chemiosmosis by ATP synthase
  5. Electrons from photosystem II are passed to photosystem I
  6. Photoactivation excites electrons in photosystem I
  7. NADPH is produced using electrons from the photosystem
  8. Electrons from photolysis are needed in photosystem II
  9. Oxygen is a waste product of photolysis

  10. In cyclic phosphorylation, electrons from photosystem I return to it
• What are the products of the light dependent reaction?

  Oxygen, NADPH, and ATP
• What is the role of NADP in photosynthesis?

  NADP is the terminal electron acceptor
• What is photophosphorylation?

  • Production of ATP
  • Light is absorbed by photosystem I
  • Photolysis separates hydrogen from its electrons
  • Electrons move through carriers in the thylakoid membrane
  • Protons build up in the thylakoid space
  • Protons move through ATP synthase to produce ATP
  • ATP synthase is a protein complex in the thylakoid membrane
  • Chemiosmosis links proton gradient and ATP synthesis with electron transport
• What are the steps of the light independent reactions (Calvin cycle)?

  1. Carbon fixation
  2. Reduction of G3P to TP
  3. Synthesis of glucose
  4. Regeneration of RuBP
• What occurs during carbon fixation in the Calvin cycle?

  Carboxylation by enzyme rubisco in the stroma combines 3 carbon dioxide with 3 RuBP to produce a 6C compound
• What is produced during the reduction of G3P to TP?

  Produces 6 ADP and Pi from ATP and oxidizes 6 NADPH to 6 NADP and protons
• How is glucose synthesized in the Calvin cycle?

  One TP is used to make half a glucose
• What happens during RuBP regeneration?

  5 molecules of TP are used to make 3 RuBP, and 3 ATP produces 3 ADP and Pi
• What is produced in the Krebs cycle?

  • 6 molecules of TP are produced per cycle
  • One TP makes half a glucose
  • Two cycles make one glucose
  • Produces glucose, NADP, and ADP + Pi
• What is the role of chlorophyll in photosystem II during the light-dependent reaction?

  Chlorophyll absorbs light and produces an excited electron through photoactivation.
• What happens during photophosphorylation in the light-dependent reaction?

  Electrons pass from carrier to carrier along the electron transport chain (ETC).
• What is the effect of protons being pumped along the thylakoid membrane?

  Protons are pumped into the thylakoid space, creating a proton gradient.
• How is ATP produced during the light-dependent reactions?

  ATP is produced through chemiosmosis by ATP synthase.
• What happens to electrons from photosystem II after they are excited?

  Electrons from photosystem II are passed to photosystem I.
• What occurs during the photoactivation of electrons in photosystem I?

  Electrons in photosystem I are excited to a higher energy level.
• What is produced using electrons from photosystem I?

  NADPH is produced using electrons from photosystem I.
• Why are electrons from photolysis important in photosystem II?

  Electrons from photolysis are needed to replace those lost in photosystem II.
• What is a waste product of photolysis?

  Oxygen is a waste product of photolysis.
• What is the process of cyclic phosphorylation in photosystem I?


  • Electrons from photosystem I return to it after being excited.
  • This process allows for the continuous production of ATP.