Energy Transfers

• What are the two main stages of photosynthesis?

  Light dependent and light independent reactions

  
• Where does the light-dependent reaction occur?

  Thylakoid membrane of chloroplast

  
• Where does the light-independent reaction occur?

  Stroma of chloroplast
• What happens during photoionisation in the light-dependent reaction?

  Chlorophyll absorbs light energy, exciting electrons

  
• What occurs after photoionisation in the light-dependent reaction?

  Electrons move along the electron transfer chain

  
• How is ATP produced during the light-dependent reaction?

  Protons move through ATP synthase, forming ATP

  
• What is photolysis of water in the light-dependent reaction?

  Water splits into protons, electrons, and oxygen

  
• What is the first step of the Calvin cycle in the light-independent reaction?

  CO2 reacts with ribulose bisphosphate (RuBP)
• What enzyme catalyzes the reaction between CO2 and RuBP?

  Rubisco
• What happens to glycerate 3-phosphate (GP) in the Calvin cycle?

  GP is reduced to triose phosphate (TP)
• What happens to some triose phosphate (TP) in the Calvin cycle?

  Some TP is converted to useful organic substances
• How does temperature affect the rate of photosynthesis?

  Rate increases with temperature until enzymes denature

  
• What happens to enzymes at temperatures above the optimum?

  Enzymes denature as hydrogen bonds break
• How does light intensity affect the rate of photosynthesis?

  Rate increases with light intensity until a limiting factor occurs

  
• What happens to the light-independent reaction as light intensity increases?

  More ATP and reduced NADP are produced

  
• How does CO2 concentration affect the rate of photosynthesis?

  Rate increases with CO2 concentration until a limiting factor occurs

  
• What is the key consideration when evaluating agricultural practices?

  Profit from yield must exceed costs
• What does respiration produce?

  ATP to release energy
• What are the stages of aerobic and anaerobic respiration?

  Aerobic respiration:

  1. Glycolysis - cytoplasm (anaerobic)
  2. Link reaction - mitochondrial matrix
  3. Krebs cycle - mitochondrial matrix
  4. Oxidative phosphorylation - inner mitochondrial membrane

  
  

  Anaerobic respiration:

  1. Glycolysis - cytoplasm
  2. NAD regeneration - cytoplasm
• What is the process of glycolysis?

  Glucose is phosphorylated, hydrolyzed, and oxidized

  
• What happens to pyruvate in anaerobic respiration?

  Converted to lactate or ethanol

  
• Why does anaerobic respiration produce less ATP?

  Only glycolysis occurs, producing little ATP
• What happens to pyruvate in aerobic respiration?

  Pyruvate is transported into the mitochondrial matrix
• What occurs during the link reaction?

  Pyruvate is oxidized to acetate, producing CO2

  
• What is produced in the Krebs cycle per glucose molecule?

  6 reduced NAD, 2 reduced FAD, 2 ATP, 4 CO2

  
• What is oxidative phosphorylation?

  Process of ATP production using electron transfer chain

  
• What is the role of oxygen in oxidative phosphorylation?

  Oxygen is the final electron acceptor
• How is biomass formed in plants?

  Plants make organic compounds from CO2
• How can biomass be measured?

  Mass of carbon or dry mass of tissue
• Why is dry mass more representative than fresh mass?

  Water volume in wet samples varies
• How can chemical energy in dry biomass be estimated?

  Using calorimetry to measure heat released
• What is gross primary production (GPP)?

  Total energy transferred into chemical energy
• What is net primary production (NPP)?

  Energy store after respiratory losses accounted
• What is the significance of biomass in ecosystems?

  It represents energy available to consumers
• Does water volume in wet samples affect dry mass?

  No, it does not affect dry mass.
• How can the chemical energy stored in dry biomass be estimated?

  By using calorimetry to measure heat energy.
• What are the steps in estimating chemical energy using calorimetry?

  1. Fully combust known mass of dry biomass.
  2. Heat a known volume of water.
  3. Calculate chemical energy from temperature increase.
• What is the function of a stirrer in a calorimeter?

  It evenly distributes heat energy in water.
• How does insulation in a calorimeter help measurements?

  It reduces heat loss and gain from surroundings.
• Why is water used in calorimetry?

  It has a high specific heat capacity.