Bioenergetics

• Photosynthesis


  A chemical reaction which takes place in plants, converting carbon dioxide and water into glucose and oxygen using light energy absorbed by chlorophyll
• Photosynthesis


  1. Measure light

  2. Collect pondweed

  3. Clamp pondweed

  4. Place in boiling tube

  5. Wait two minutes

  6. Measure bubbles produced

  7. Repeat at different distances
• Photosynthesis


  • An endothermic reaction
  • Takes place inside chloroplasts in plant cells
  • Plants acquire carbon dioxide via diffusion through stomata
  • Plants absorb water from soil through roots and transport it via xylem
• Products of photosynthesis


  • Glucose
  • Oxygen
• Uses of glucose produced in photosynthesis

  • Respiration
  • Stored as starch, fat or oils
  • Produce cellulose
  • Produce amino acids for protein synthesis
• Limiting factors for rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide level
• Increasing temperature


  Increases rate of photosynthesis up to 45°C, then enzymes become denatured
• Increasing light intensity


  Increases rate of photosynthesis
• Increasing carbon dioxide concentration

  Increases rate of photosynthesis
• Inverse square law


  Light intensity is inversely proportional to the square of the distance from the source
• Respiration


  The chemical reaction in the mitochondria of cells to release energy for living functions and processes
• Aerobic respiration


  Glucose + Oxygen → Carbon dioxide + Water + ATP
• Anaerobic respiration

  Glucose → Lactic acid + ATP
• During exercise


  Respiration rate increases to meet increased energy demand, leading to oxygen debt if oxygen supply is insufficient
• Metabolism


  The combination of all the chemical reactions in a cell or body, including respiration and other processes to synthesise new molecules
• Oxygen debt


  The amount of oxygen required by the body to convert built-up lactic acid back into glucose and remove it from respiring cells
• Greenhouse economics can be used to grow plants in optimal conditions by controlling temperature, light, and carbon dioxide levels