bioenergetics

• Lactic acid processing


  1. Lactic acid is transported to the liver by the blood

  2. Lactic acid is oxidised to CO₂ and H₂ or converted to glucose, then glycogen

  3. Restores glycogen in the liver and muscles
• Period of activity is over


  Breathing and heart rate is not restored straightaway
• Oxygen debt


  The amount of oxygen required to remove lactic acid, and replace the body's reserve of oxygen
• Bringing more oxygen into the body


  Increases the heart rate
• Muscles continue to contract during long periods of vigorous activity
• Lactic acid builds up during long periods of vigorous activity, producing an oxygen debt
• Respiration


  An exothermic reaction that releases energy to drive chemical reactions needed to keep organisms alive and enable movement
• Respiration is only around 40% efficient
• Heat


  Heat is released and distributed around the body by the blood, keeping animals warm and at a constant temperature
• Aerobic respiration


  Glucose + oxygen -> carbon dioxide + water + energy
• Anaerobic respiration


  1. Glucose -> lactic acid + energy (in muscles)

  2. Glucose -> ethanol + carbon dioxide (in yeast)
• Light intensity increases


  The rate of photosynthesis increases
• Carbon dioxide concentration increases

  The rate of photosynthesis increases
• Temperature


  Photosynthesis is an enzyme-controlled reaction, so at low temperatures the rate is limited by enzyme-substrate collisions, and at high temperatures the enzymes are denatured
• Chlorophyll


  Leaves with more chlorophyll are better able to absorb the light required for photosynthesis
• Measuring photosynthesis rate


  1. Set up a boiling tube with sodium hydrogen carbonate solution

  2. Cut a piece of pondweed and place in the tube

  3. Position the tube near a light source

  4. Count the number of bubbles emerging from the pondweed in 1 minute

  5. Repeat the count 5 times and calculate the average
• Photosynthesis


  Carbon dioxide + water -> Glucose + oxygen
• Photosynthesis


  An endothermic reaction that requires light energy absorbed by chlorophyll in the chloroplasts
• Carbon dioxide for photosynthesis comes from the air, entering through the stomata
• Water for photosynthesis enters through the roots and is transported to the leaves in the xylem
• Glucose produced in photosynthesis is used to build up fats, oils, cellulose, amino acids, starch, and for respiration
• Metabolism


  The chemical reactions that build up and break down molecules inside an organism's body
• The liver has many different metabolic functions including detoxifying, excreting waste, and storing iron