Bioenergetics

• Photosynthesis is the process by which plants make glucose from sunlight
• Photosynthesis is an endothermic reaction where energy is transferred from the environment to the chloroplasts by light
• The equation for photosynthesis is: light + carbon dioxide + water → glucose + oxygen
• Factors affecting the rate of photosynthesis:

  • Temperature: Increasing temperature increases the rate of photosynthesis until enzymes denature
  • Light intensity: Higher light intensity leads to a faster reaction
  • Carbon dioxide concentration: Increasing concentration increases the rate of reaction
  • Amount of chlorophyll: Essential for converting light energy to food for the plant
• Experiment to measure the rate of photosynthesis:

  • Oxygen production of a plant is measured
  • Variables that can be changed include temperature, time, and light intensity
  • Limiting factors can restrict the rate of photosynthesis despite other factors increasing
• Light intensity is measured in lux

  • Limiting factors can be identified in graphs
  • Farmers can enhance greenhouse conditions based on limiting factors for increased growth and profits
• Uses of glucose from photosynthesis:

  1. For respiration

  2. Converted into insoluble starch for storage

  3. To produce fat or oil for storage

  4. To produce cellulose to strengthen cell walls

  5. Combined with nitrates to form amino acids for proteins
• Respiration is the process of transferring energy from glucose for living processes

  • It can occur aerobically (with oxygen) or anaerobically (without oxygen)
• Response to exercise:

  • During exercise, more energy is needed for muscle contraction
  • Aerobic respiration uses oxygen and yields the most energy
  • Anaerobic respiration occurs when there is not enough oxygen and does not yield as much energy
• Anaerobic respiration:

  • Lactic acid is produced as a byproduct
  • Oxygen debt occurs when lactic acid accumulates, leading to muscle fatigue
• Metabolism is the sum of all reactions in a cell or body

  • Energy from respiration is used in metabolic processes controlled by enzymes