bioenergetics

• Photosynthesis


  Process that happens in plants and algae where carbon dioxide from the air enters the leaves by diffusion, water from the soil enters the roots by osmosis, sunlight is absorbed by chlorophyll in chloroplasts, and glucose is produced with oxygen as a waste product
• Photosynthesis


  Carbon dioxide + water → glucose + oxygen
• Endothermic reaction


  Energy is transferred from the surroundings to chloroplasts by light
• Uses of glucose produced in photosynthesis

  • Used in respiration to release energy
  • Converted to insoluble starch for storage
  • Used to make fats or oils for energy storage
  • Used to produce cellulose to strengthen cell walls
  • Combined with nitrates to make amino acids for proteins
• Limiting factors in photosynthesis

  • Light intensity
  • Carbon dioxide concentration
  • Temperature
  • Amount of chlorophyll present
• As light intensity increases

  The rate of photosynthesis increases
• As carbon dioxide concentration increases

  The rate of photosynthesis increases
• As temperature increases


  The rate of photosynthesis increases (up to an optimal temperature)
• As temperature continues to increase beyond the optimal

  The rate of photosynthesis decreases rapidly due to enzyme denaturation
• Greenhouse conditions


  • Maximizing photosynthesis while maintaining profits
• Increasing carbon dioxide concentration and temperature

  Increases the maximum rate of photosynthesis
• There is a limit to how much light intensity can be increased, as beyond a certain point there is no further increase in the rate of photosynthesis</b>
• Measuring the rate of photosynthesis

  Can be done by counting the number of oxygen bubbles produced per minute or measuring the volume of oxygen produced per minute
• Photosynthesis rate experiment


  Set up pondweed, add sodium bicarbonate, vary distance of lamp, count bubbles per minute, plot graph of bubbles/minute vs distance
• Control variables for photosynthesis rate experiment

  • Same pondweed, same length, same temperature, same carbon dioxide concentration, repeat 3 times
• Changing light color by using filters can also affect the rate of photosynthesis
• Inverse Square Law


  Light intensity is proportional to 1/distance^2
• Doubling the distance of the light source

  Reduces the light intensity to 1/4 of the original
• Doubling the distance of the light source

  Reduces the rate of photosynthesis to 1/4 of the original
• Inverse square law


  Light intensity is inversely proportional to the square of the distance from the light source
• Inverse square law examples

  • Distance 10 cm, light intensity 180 Lux, photosynthesis rate 60 bubbles/min
  • Distance 20 cm, light intensity 45 Lux, photosynthesis rate 15 bubbles/min
  • Distance 30 cm, light intensity 20 Lux, photosynthesis rate 7 bubbles/min
  • Distance 60 cm, light intensity 5 Lux, photosynthesis rate 2 bubbles/min
• Respiration


  Process that provides energy for all living things, can be aerobic (using oxygen) or anaerobic (without oxygen)
• Aerobic respiration


  1. Oxygen taken into lungs

  2. Glucose from digestive system transported in blood

  3. Respiration in cells releases energy, CO2 and water
• Aerobic respiration equation


  Glucose + Oxygen → Carbon dioxide + Water
• Anaerobic respiration in animal cells

  Glucose converted to lactic acid, less energy released
• Anaerobic respiration in plant and yeast cells

  Glucose converted to ethanol and CO2, much less energy released
• Fermentation


  Anaerobic respiration in yeast, produces CO2 that makes bread dough rise, and produces ethanol for alcoholic drinks
• Comparison of aerobic and anaerobic respiration in plants, animals and yeast

  • Tick/cross grid
• Response to exercise


  1. Increased breathing rate

  2. Increased heart rate

  3. Increased aerobic respiration in muscle cells

  4. Anaerobic respiration can occur, producing lactic acid
• Oxygen debt


  Extra oxygen needed after exercise to remove lactic acid from cells
• Metabolism


  1. Conversion of simple sugars to complex carbohydrates

  2. Conversion of amino acids to proteins

  3. Conversion of fatty acids and glycerol to lipids

  4. Breakdown of excess amino acids to urea for excretion

  5. Conversion of glucose to glycogen for storage