photosynthesis

• What are autotrophs?


  Organisms that make their own food
• What do photoautotrophs do?


  They transform sunlight energy into chemical energy using CO2 and H2O
• How do chemoautotrophs obtain their nutrients?


  They obtain inorganic nutrients and combine them with CO2 to make organic food
• What are heterotrophs?


  Consumers that obtain organic food by eating other organisms or their by-products
• Which organisms make the majority of O2 on our planet?

  Cyanobacteria
• What is the major site of photosynthesis in plants?


  Leaves
• What is the function of stomata in plants?


  They facilitate gas exchange
• What is the organelle where photosynthesis occurs?


  Chloroplast
• What are the main components of a chloroplast?


  Double membrane, thylakoids, grana, stroma, and chlorophyll
• What is the chemical equation for photosynthesis?


  6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2
• What type of process is photosynthesis?


  It is a redox process
• What happens to water during photosynthesis?


  Water is oxidized, and electrons are transferred to CO2
• What are the two major steps of photosynthesis?


  1. Light reactions: Excite electrons in chlorophyll, produce NADPH and ATP
  2. Calvin cycle: Fix carbon into organic molecules like glucose
• What is the visible spectrum?


  The array of colors from red to violet that can be separated using a prism
• What is the role of pigments in photosynthesis?


  Pigments absorb visible light and reflect certain colors
• What are the two most common types of chlorophyll?


  Chlorophyll a and Chlorophyll b
• What are accessory pigments?


  They absorb colors that chlorophyll a cannot and help capture more light energy
• What was the conclusion of Engelmann's experiment?


  Violet-blue and red light are most effective in driving photosynthesis
• What are the phases of the Calvin cycle?


  1. Carbon fixation: CO2 attached to RuBP
  2. Reduction: Electrons from NADPH reduce to G3P
  3. Regeneration: G3P rearranged to RuBP

  
• What is chemiosmosis?


  The process of making ATP using a proton concentration gradient across membranes
• What is the role of ATP synthase in chloroplasts?


  It uses the proton-motive force to make ATP
• How do light reactions and the Calvin cycle differ?


  • Light reactions: Convert light energy to ATP and NADPH, release O2
  • Calvin cycle: Use ATP and NADPH to convert CO2 to G3P
• How do chloroplasts and mitochondria generate ATP?


  Both use chemiosmosis but different energy sources
• What is the spatial organization of chemiosmosis in chloroplasts?


  It occurs across the thylakoid membrane and stroma
• What is the main product of the Calvin cycle?


  G3P (glyceraldehyde 3-phosphate)
• What happens to G3P produced in the Calvin cycle?


  It can be used to make glucose and other organic compounds
• What is cyclic electron flow?


  An alternative cycle when ATP is deficient, using Photosystem I only
• What are the key differences between light reactions and Calvin cycle reactions?

  • Light reactions: Occur in thylakoid membranes, produce ATP and NADPH, split water
  • Calvin cycle: Occur in stroma, use ATP and NADPH to convert CO2 to G3P
• What is the role of RuBP in the Calvin cycle?

  RuBP is the molecule to which CO2 is attached during carbon fixation
• What is the significance of the porphyrin ring in chlorophyll?


  It is the light-absorbing "head" of the molecule
• How does the structure of chlorophyll a differ from chlorophyll b?

  A slight difference in molecular structure allows them to absorb different colors of light