bioenergetics

• lipids and proteins


  2 reactions of metabolism
• Lipids (cell membrane)


  • Glycerol+3 fatty acids
• Proteins

  In excess protein broken down by chemical urea
• Metabolism


  The sum of all chemical reactions in a cell or the body
• Glucose


  An important chemical in metabolism (the starting point)
• Cellulose


  • Strengthens cell wall
• Starch

  • Storage form of glucose (plants)
• Amino acids


  • Synthesises protein - combined with nitrate ions
• Glycogen


  • Storage form of glucose
• Exercise


  Body needs a great deal of energy for muscle contraction
• Aerobic respiration increases


  Body cells need more oxygen, breathing rate and volume increases, heart rate increases to pump more oxygenated blood
• Oxygen supply is insufficient

  Anaerobic respiration takes place in the muscles
• Lactic acid is excreted by kidneys
• Respiration


  Takes place in the mitochondria, is an exothermic reaction as it releases energy
• Aerobic respiration


  Glucose + oxygen -> carbon dioxide + water, releases a lot of energy as the glucose has been fully oxidised
• Anaerobic respiration


  Glucose -> lactic acid, releases less energy than aerobic respiration as the oxidation of glucose is incomplete
• In plants, glucose -> ethanol + carbon dioxide
• Fermentation


  Anaerobic respiration in yeast used to for bread(carbon dioxide)
• Fermentation in bread making produces carbon dioxide, causing bread to rise
• Photosynthesis


  The reaction that plants use to trap light energy
• Plants use light for their source of energy
• Photosynthesis

  • It is an endothermic reaction
  • It takes place in the leaves of a plant
  • Leaves contain the green chemical chlorophyll
• Photosynthesis

  1. Plant takes in carbon dioxide and water

  2. Light energy is absorbed by chlorophyll

  3. Light energy is used to convert carbon dioxide and water into glucose

  4. Oxygen is also produced
• Chemical formulas

  • Carbon dioxide (CO2)
  • Water (H2O)
  • Glucose (C6H12O6)
  • Oxygen (O2)
• Light intensity increases


  Rate of photosynthesis increases
• Limiting factor


  The factor that is in short supply and is limiting the rate of photosynthesis
• Carbon dioxide level increases

  Rate of photosynthesis increases
• Factors affecting rate of photosynthesis

  • Light intensity
  • Carbon dioxide level
  • Amount of chlorophyll in leaf
  • Temperature
• As temperature increases, enzymes involved in photosynthesis work faster, increasing the rate, but if temperature keeps increasing, enzymes will denature and the rate will fall
• Photosynthesis


  Carbon dioxide + water + light energy → Glucose + Oxygen
• Respiration


  Process that releases energy from glucose in the mitochondria
• Photosynthesis only produces glucose during the day


  Plant cells respire all the time, including at night
• Starch


  Insoluble storage molecule made from glucose, which can be converted back to glucose when needed
• Fats and oils


  Storage form of energy made from glucose in many plants
• Cellulose


  Molecule in the plant cell wall, made from glucose, that gives it strength
• Amino acids


  Made from glucose, used by plants to synthesize proteins
• Peas are a good protein source
• Investigating the effect of light intensity on the rate of photosynthesis


  1. Take a boiling tube and place it 10 cm away from an LED light source

  2. Fill the boiling tube with sodium hydrogen carbonate solution

  3. Put a piece of pond weed into the boiling tube

  4. Leave for 5 minutes to acclimatize

  5. Count the number of bubbles produced in 1 minute
• Repeating the experiment at different distances

  1. Repeat the experiment at 20 cm, 30 cm, and 40 cm from the light source

  2. Calculate the mean number of bubbles produced per minute at each distance
• Problems with counting bubbles


  • Bubbles can be too fast to count accurately
  • Bubbles are not always the same size