B4 - Bioenergetics

• Photosynthesis


  • Takes place in chloroplasts in green plant cells
  • Chloroplasts Contains pigments like chlorophyll that absorb light
• Photosynthesis is endothermic

  Energy is transferred from the environment in the process
• Photosynthesis equation


  1. Carbon dioxide + water ---> glucose + oxygen

  2. 6CO2 + 6H2O ---> C6H12O6 + 6O2
• Ways plants use glucose

  • For respiration
  • Making cellulose
  • Making amino acids
  • Stored as oils or fats
  • Stored as starch
• Limiting factor


  Something that prevents a process from happening any faster
• Limiting factors of photosynthesis

  • Intensity of light
  • Concentration of carbon dioxide
  • Chlorophyll
  • Temperature
• Photosynthesis Required Practical


  1. Place a piece of pondweed (Elodea or Cabomba are often used), into a beaker of water

  2. Use a light a set distance from the plant

  3. Record the number of bubbles observed in three minutes

  4. Repeat steps for different distances
• The Photosythesis required practical has an inversely proportionate trend when the results are plotted
• Greenhouses


  • Trap the sun's heat
  • Can add a heater during the winter
  • Protect plants from pests and diseases
• Greenhouses cost money
• Inverse Square Law


  $\frac{1}{distance^2 }$
• What is respiration?


  It is the process of transferring energy from glucose in every cell.
• What is the equation for aerobic respiration?


  Aerobic respiration is represented as glucose + oxygen → carbon dioxide + water (+ energy).
• What is the chemical equation for aerobic respiration?

  $C_6H_{12}O_6 +$$6O_2 \rightarrow 6CO_2 +$$6H_2O$
• What happens during anaerobic respiration in muscle cells?


  Glucose is converted to lactic acid (+ energy).
• What is anaerobic respiration fermentation?


  It is the process where glucose is converted to ethanol and carbon dioxide (+ energy).
• What are the uses of energy in humans?

  • Maintaining body temperature
  • Cell division and growth
  • Active transport
  • Nerve impulses
  • Muscle contraction
  • Protein synthesis
• How is glucose used in plants?


  • Respiration
  • To make protein, cellulose, and fats
  • Converted to fructose (fruit), sucrose (transport), starch (storage)
• What is oxygen debt?


  It is when you require more oxygen than you have.