B4: Bioenergetics

• Photosynthesis


  1. Happens in chlorophyll and chloroplasts in plant cells

  2. Provides food for the plant

  3. Requires light energy (endothermic reaction)

  4. Produces glucose
• Glucose from photosynthesis


  Used for respiration or turned into starch or fat for energy storage
• Cellulose


  Used to produce cell walls
• Amino acids


  Used for synthesizing proteins
• Factors that increase the rate of photosynthesis

  • Higher temperature (up to a point)
  • Higher light intensity
  • Higher CO2 concentration
• Limiting factors for photosynthesis

  If one factor is low, the rate will be limited by that factor even if the other factors are high
• Measuring the rate of photosynthesis

  1. Submerge pondweed in inverted measuring cylinder

  2. Measure volume of oxygen produced over time

  3. Can also count bubbles (less accurate)
• Light intensity


  Follows an inverse square relationship (doubling distance quarters intensity)
• Aerobic respiration


  1. Occurs in mitochondria

  2. Releases energy for the organism

  3. Opposite of photosynthesis
• During exercise


  Breathing rate and heart rate increase to deliver more oxygen for respiration
• Anaerobic respiration


  1. Occurs when there is a lack of oxygen

  2. Glucose converted to lactic acid (less energy released)

  3. Causes muscle ache

  4. Oxygen debt built up that needs to be repaid after exercise
• Anaerobic respiration in plants and yeast

  1. Glucose converted to ethanol and CO2

  2. Causes bread/dough to rise

  3. Used to make alcoholic drinks
• Metabolism


  The sum of all reactions in a cell or organism, including respiration, conversion of glucose, and breakdown of excess proteins
• Glucose and nitrates are used to make amino acids for protein synthesis
• Fatty acids and glycerol are built up into lipids
• Excess proteins are broken down into urea