Energy for Biological Processes

• What is photosynthesis?

  A reaction using light energy to produce glucose
• What is the purpose of photolysis in photosynthesis?

  To split water molecules for hydrogen
• What is produced as a waste product of photosynthesis?

  Oxygen
• What factors determine the rate of photosynthesis?

  Carbon dioxide concentration, light intensity, temperature
• Where does photosynthesis occur in plant cells?

  In the chloroplast
• How is the chloroplast adapted for photosynthesis?

  • Contains stacks of thylakoid membranes (grana)
  • Contains photosynthetic pigments like chlorophyll
  • Has stroma with enzymes for light-independent reactions
• What are the two stages of photosynthesis?

  Light-dependent and light-independent reactions
• What happens during the light-dependent reaction?

  Electrons are excited and ATP is generated
• What is photophosphorylation?

  Process generating ATP from ADP and phosphate

  
• What is the Calvin cycle also known as?

  Light-independent reaction
• What is produced alongside ATP in the light-dependent stage?

  Reduced NADP (NADPH)
• What are the steps of the Calvin cycle?

  1. Carbon fixation with RuBP and CO2
  2. Conversion of RuBP to glycerate 3-phosphate (GP)
  3. Conversion of GP to triose phosphate (TP)
  4. Some TP is used to make glucose
  5. Remaining TP reforms RuBP using ATP
• What is a limiting factor in photosynthesis?

  The factor in lowest supply affecting rate
• How does low light intensity affect photosynthesis?

  Slows light-dependent reactions, reducing ATP and NADPH
• What happens if CO2 concentration is low?

  The light-independent reaction will slow down
• How does low temperature affect photosynthesis?

  Reduces kinetic energy of Rubisco and enzymes
• What is aerobic respiration?

  Respiration using oxygen to release energy
• What is the main difference between aerobic and anaerobic respiration?

  Aerobic uses oxygen, anaerobic does not
• What is glycolysis?

  • First step of both aerobic and anaerobic respiration
  • Occurs in the cytoplasm
  • Converts glucose to 2 pyruvate, 2 NADH, and 2 ATP
• What happens during the link reaction in aerobic respiration?

  Pyruvate is converted to acetyl and CO2 is released

  
• What does coenzyme A do in respiration?

  Delivers acetyl to the Krebs cycle

  
• What are the products of the Krebs cycle per glucose molecule?

  • 4 CO2
  • 4 NADH
  • 2 FADH
  • 2 ATP
• What is oxidative phosphorylation?

  Process synthesizing ATP in the electron transport chain

  
• How is ATP produced in the Krebs cycle?

  By substrate-level phosphorylation
• What is the theoretical yield of ATP per glucose molecule?

  38 ATP molecules
• What occurs during oxidative phosphorylation?

  • Reduced coenzymes deliver electrons to the chain
  • Electrons move through carriers in redox reactions
  • Hydrogen ions are pumped into the intermembrane space
  • ATP is produced via ATP synthase
  • Oxygen acts as the final electron acceptor
• Why is the theoretical yield of ATP rarely achieved?

  Inner membrane is leaky to H+
• What are respiratory substrates?

  Carbohydrates, lipids, and proteins used in respiration
• How is the respiratory quotient (RQ) calculated?

  RQ = CO2 produced / O2 consumed
• What are the RQ values for carbohydrates, lipids, and proteins?

  Carbs: 1.0, Lipids: 0.8, Proteins: 0.9
• What happens during anaerobic respiration?

  ATP is produced without oxygen
• What is produced from pyruvate in mammals during anaerobic respiration?

  Lactate
• How does lactate convert back to pyruvate?

  In liver cells when oxygen levels rise
• What is alcoholic fermentation in yeast and plants?

  Conversion of pyruvate to ethanol and CO2

  
• What is the first step of alcoholic fermentation?

  Decarboxylation of pyruvate to produce CO2