Unit 3, AoS 2

• Explain what occurs during photosynthesis

  Chlorophyll in the chloroplasts absorb light energy, converting carbon dioxide into oxygen and glucose, providing the cell with energy
• Differentiate between thylakoids, grana and stroma (components of a chloroplast)

  • Thylakoid: a flattened membrane-bound sac containing chlorophyll
  • Grana: stack of thylakoids
  • Stroma: fluid between grana
• What are the inputs and outputs of the light dependent stage?

  Inputs

  • 12NADP+, 18ADP+Pi, 12H2O, Light energy

  Outputs

  • 12NADPH, 18ATP, 6O2
• What are the inputs and outputs of the light independent stage?

  Inputs

  • 12NADPH, 18ATP, 6CO2

  Outputs

  • C6H12O6, 6H2O
• Explain what happens in the Calvin Cycle

  Rubisco enzyme converts carbon dioxide into glucose, using ATP to break carbon molecules into different configurations. Occurring in the light independent stage of photosynthesis, in the stroma
• Explain C4 photosynthesis


  An adaptation of plants, to combat the active site shape change of Rubisco that occurs at hot temperatures. Bundle sheath cells around vascular tissue in C4 photosynthesising plants limits the amount of oxygen that can interrupt the Calvin Cycle, therefore limiting photorespiration and ensuring that only carbon dioxide is able to be used in the cycle (thereby producing glucose)
• Explain CAM photosynthesis


  Adaptations in plants in hot environments, whereby stomata of plant only opens at night, as evaporation due to heat is lower, and more carbon dioxide can be taken in. Carbon dioxide absorbed during the night is stored as malic acid (malate) until the day until it can be used
• Describe the factors which impact rate of reaction for photosynthesis

  • Temperature - rate of photosynthesis increases as it nears optimal (25 degrees), until Rubisco affinity for oxygen increases, causing photorespiration
  • light intensity - photosynthesis increases with light intensity, before levelling off
  • wavelength - preference for red/blue light increases rate of photosynthesis, slowest when exposed to green light
  • CO2 concentration - higher concentration = increased rate
• Aerobic cellular respiration


  Takes place in the mitochondria, focusses on the breakdown of glucose into ATP, energy which can be used in the cell

  Glucose + oxygen -> carbon dioxide + water
• Explain the role of NADH and FADH2 in aerobic cellular respiration

  act as coenzymes, which carry electrons across the concentration gradient to fuel ATP production
• In what stage of aerobic cellular respiration is the largest ATP yield?

  Electron transport chain
• What are the inputs and outputs of each stage of aerobic cellular respiration?

  Glycolysis - NAD+ -> NADH, glucose -> 2pyruvate, 2ATP

  Krebs cycle - NAD+ -> NADH, FAD+ -> FADH2, 6CO2, 2ATP

  Electron transport chain - FADH2 -> FAD+, NADH -> NAD+, 6H2O, 6O2, 26 or 28 ATP

  
• What is anaerobic cellular respiration?

  The breakdown of glucose to 2ATP following the absence of oxygen. Produces considerably less ATP compared to aerobic cellular respiration. Also called fermentation

  Animal cells: (2ADP+Pi) Glucose -> lactic acid + 6CO2 (2ATP)

  Yeast: (2ADP+Pi) Glucose -> ethanol + 6CO2 (2ATP)
• What are biofuels?


  Derived from the anaerobic fermentation of biomass. Ethanol as a bioproduct of fermentation (yeast) can be used to create fuel