Bioenergetics

• Photosynthesis

  Produces Glucose Using Light
• Photosynthesis

  1. Carbon dioxide + water

  2. Glucose + oxygen
• Ways plants use glucose

  • Formation of new plant biomass
  • Making cellulose
  • Making amino acids
  • Storing as oils or fats
  • Storing as starch
• Photosynthesis

  Putting together using light
• Limiting factors

  • Light
  • Carbon dioxide
  • Temperature
• Light intensity increases

  Rate of photosynthesis increases
• Carbon dioxide concentration increases

  Rate of photosynthesis increases
• Temperature increases

  Rate of photosynthesis increases (up to an optimal temperature)
• Temperature increases further

  Enzymes needed for photosynthesis are destroyed
• One graph may show the effect of many limiting factors on the rate of photosynthesis
• Oxygen production can be used to measure the rate of photosynthesis
• Inverse square law

  Light intensity is inversely proportional to the square of the distance from the light source
• If distance is doubled, light intensity becomes 1/4 of the original
• If distance is tripled, light intensity becomes 1/9 of the original
• Greenhouses

  • Trap heat
  • Allow temperature control
  • Provide supplementary lighting
• Farmers and gardeners can increase the carbon dioxide levels to improve photosynthesis
• Ideal Conditions for Photosynthesis

  • Greenhouse traps Sun's heat to maintain ideal temperature
  • Artificial light provided after sunset to extend photosynthesis time
  • Carbon dioxide levels increased using paraffin heater
  • Pest and disease control easier in greenhouse environment
  • Fertilizers added to soil to provide minerals for healthy growth
• Growing plants outdoors can be very difficult especially on a large scale due to weather and other conditions
• Greenhouse

  Artificial environment created to provide ideal conditions for plant growth
• How greenhouses create ideal conditions

  1. Trap Sun's heat

  2. Use heaters in winter

  3. Use shades and ventilation in summer

  4. Provide artificial light

  5. Increase carbon dioxide levels

  6. Control pests and diseases

  7. Add fertilizers to soil
• Keeping conditions just right for photosynthesis allows plants to grow much faster and produce a decent crop more often
• Respiration is the process of transferring energy from glucose
• Respiration

  Not just breathing in and out, but the chemical process of extracting energy from glucose
• Respiration transfers energy for all kinds of living processes
• Examples of how organisms use energy from respiration

  • Building up molecules from smaller ones
  • Allowing muscles to contract and move
  • Maintaining body temperature in cold environments
  • Powering other processes in the body
• Cyanide is a toxin that stops respiration by interfering with the process
• Metabolism

  All the chemical reactions happening in an organism, controlled by enzymes
• Metabolism includes

  1. Reactions that join smaller molecules into larger ones

  2. Reactions that break down larger molecules into smaller ones
• Enzymes are key to metabolism
• Aerobic respiration

  Respiration that uses oxygen
• Anaerobic respiration

  Respiration without oxygen
• Aerobic respiration

  Glucose + oxygen -> carbon dioxide + water
• Anaerobic respiration in muscle cells

  Glucose -> lactic acid
• Anaerobic respiration in plant and yeast cells

  Glucose -> ethanol + carbon dioxide
• Fermentation

  Anaerobic respiration in yeast cells, used to make bread, beer, and wine
• When you exercise

  Your body respires more to provide energy for muscle contraction
• Vigorous exercise

  Leads to anaerobic respiration and buildup of lactic acid in muscles
• After exercise

  You have an "oxygen debt" that needs to be repaid by continued heavy breathing
• Investigating the effect of exercise on the body

  1. Measure breathing rate by counting breaths

  2. Measure heart rate by taking pulse
• Vigorous exercise leads to anaerobic respiration and oxygen debt