Bioenegetics

• Photosynthesis


  Produces glucose using light
• Photosynthesis


  Carbon dioxide + water -> glucose + oxygen
• Ways plants use glucose


  • Cellular respiration
  • Making cellulose
  • Making amino acids
  • Stored as oils or fats
  • Stored as starch
• Limiting factors of photosynthesis


  • Intensity of light
  • Concentration of CO2
  • Temperature
• Any of the three limiting factors can be the factor that is chopping photosynthesis from happening any faster
• The limiting factor depends on the environmental conditions
• Chlorophyll can also be a limiting factor of photosynthesis
• Factors that can affect the amount of chlorophyll include disease and environmental stress
• Relationship between light intensity and rate of photosynthesis


  • Not enough light slows down the rate
  • Rate increases steadily as light intensity increases, up to a point
  • Beyond that point, increasing light intensity makes no difference
• Relationship between CO2 concentration and rate of photosynthesis


  • Rate increases as CO2 increases, up to a point
  • After that point, increasing CO2 no longer increases the rate
• Relationship between temperature and rate of photosynthesis


  • Rate increases as temperature increases, up to an optimal temperature
  • Above the optimal temperature, enzymes are damaged and the rate decreases
• The apparatus used to measure the rate of photosynthesis can be altered to measure the effect of temperature or CO2
• Inverse square law

  Light intensity is inversely proportional to the square of the distance from the light source
• Advantages of growing plants in a greenhouse


  • Can control temperature, light, CO2 and nutrients to provide ideal conditions for photosynthesis
  • Protects plants from pests and disease
• The plants will grow much faster and a decent crop can be harvested much more often, which can be sold
• It's important that a farmer supplies just the right amount of heat, light, etc. - the plants grow well, but not more than the plants need, as this would just be wasting money
• Don't blame it on the sunshine, don't blame it on the CO2
• Now don't let the inverse square law put you off learning everything on these past three pages
• An experiment was carried out to find out the effect of temperature on the rate of photosynthesis
• Variables that should have been controlled in the experiment

  • Two variables
• Inverse square law


  Inverse relationship between light intensity and distance
• Respiration is NOT "Breathing In and Out"
• Respiration


  Process of TRANSFERRING ENERGY FROM GLUCOSE
• How organisms use the energy transferred by respiration


  • To build up larger molecules from smaller ones
  • To allow the organism to move
  • To keep their body in the right temperature
• Metabolism


  All the chemical reactions in an organism
• Examples of reactions in metabolism


  • Larger molecules made from smaller ones (e.g. starch, glycogen, cellulose)
  • Larger molecules broken down into smaller ones (e.g. glucose broken down in respiration, protein broken down to urea)
• The sum of all the reactions that happen in a cell or the body is called its metabolism
• How animals use the energy transferred by respiration


  • To build up larger molecules
  • To allow the organism to move
  • To keep their body in the right temperature
• Aerobic respiration


  Respiration that needs plenty of oxygen
• Anaerobic respiration


  Respiration used if there's not enough oxygen
• Anaerobic respiration in muscle cells


  Glucose -> Lactic acid
• Anaerobic respiration in plants and yeast


  Produces ethanol and carbon dioxide
• Fermentation

  The process of anaerobic respiration in yeast cells
• Reactants of aerobic respiration


  • Glucose
  • Oxygen
• Anaerobic respiration leads to an oxygen debt
• Oxygen debt


  The amount of oxygen your body needs to deal with the build-up of lactic acid and remove it from the cells
• How to investigate the effect of exercise on the body


  1. Measure breathing rate and heart rate at different exercise intensities

  2. Plot the results in a bar chart
• Muscle fatigue is caused by the build-up of lactic acid