topic b4- bioenergetics

• carbon dioxide + water -> glucose + oxygen

  6CO2 + 6H2O -> C6H12O6 + 6O2

  -> = light
• photosynthesis

  an endothermic reaction in which energy is transferred to chloroplasts from the environment by light
• uses of glucose in plants

  • respiration- energy is transferred from glucose
  • strengthening cells walls- glucose is converted into cellulose, which is used to make strong cell walls
  • protein synthesis- glucose and nitrate ions are used to make amino acids, which are then made into proteins
  • energy storage- glucose is turned into lipids or insoluble starch to store energy
• limiting factors of photosynthesis

  • light intensity
  • concentration of carbon dioxide
  • temperature
  • amount of chlorophyll
• greenhouse gases

  can control the limiting factors
• the rate of photosynthesis- light intensity graph

  • light intensity on the x axis
  • rate of photosynthesis on the y axis
  • rises then plateaus
  • plateaus- co2 or temp needs increasing
  • lack of light slows down the rate of photosynthesis
• the rate of photosynthesis- % levels of co2

  • % level of co2- x axis
  • rate of photosynthesis- y axis
  • rises then plateaus
  • plateaus- light of temp needs increasing
  • lack of co2 slows down the rate of photosynthesis
• the rate of photosynthesis- temperature

  • temperature- x axis
  • rate of photosynthesis- y axis
  • rises, peaks, decreases
  • decreases- enzymes are destroyed
  • the temperature needs to be just right
• light intensity is directly proportional to

  1/ distance (d) squared
• pondweed experiment

  1. a light source is placed at a specific distance from the pondweed
  2. pondweed is left to photosynthesise; the o2 releases will collect in the capillary tube
  3. at the end of the experiment, use the syringe to draw the bubble in the tube alongside the ruler; this measures the length of the bubble
  4. the temperature and time should be controlled
  5. repeat the experiment twice the same to calculate the mean volume of o2 produced
  6. repeat the whole experiment with the light source at difference distances from the pondweed
• pondweed experiment equipment

  • light source
  • ruler
  • tube should have in it:
  • o2
  • pondweed
  • water
  • ruler
  • syringe
• metabolism

  • all the chemical reactions in and organism
  • order:
  • reactant
  • enzyme
  • product
  • enzyme
  • product
  • enzyme
  • product
• in some reactions, large molecules are made from small ones

  e.g. lipid molecules are made from 1 molecule of glycogen of glycerol + 3 fatty acids; glucose molecules are joined to make starch, glycogen, cellulose; glucose is combine with nitrate ions to make amino acids
• in some reactions, larger molecules are broken down into smaller ones

  e.g. glucose is broken down in respiration; excess protein is broken down to produce urea
• respiration

  • the process of transferring energy from glucose (exothermic reaction)
  • used to- build large molecules from small ones/ muscle to contracts/ keep body temperature steady
• aerobic respiration- respiration using oxygen

  glucose + oxygen -> carbon dioxide + water

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• anaerobic respiration- respiration without oxygen

  • in muscle cells- glucose -> lactic acid
  • in plant and yeast cells- glucose -> ethanol + carbon dioxide
  • in yeast cells anaerobic respiration is called fermentation