Respiration

• Respiration


  A chemical process where glucose is broken down to release energy to carry out different cellular processes
• Respiration happens in almost all cells in the body
• Breathing


  The physical process of inhaling oxygen and exhaling carbon dioxide in and out of our lungs
• Breathing is often confused with respiration
• Uses of energy in living organisms

  • Muscle contraction
  • Protein synthesis
  • Cell division
  • Active transport
  • Growth
  • Passage of nerve impulses
  • Maintenance of a constant body temperature
• Investigating the effect of temperature on respiration

  1. Add yeast and glucose solution to a test tube

  2. Place test tube in water bath at 30 degrees Celsius

  3. Add methylene blue indicator

  4. Start timer and shake for 10 seconds

  5. Record time taken for methylene blue to turn colorless
• Variables in the experiment

  • Independent variable: Temperature

  Dependent variable: Rate of respiration

  Controlled variables: Amount of methylene blue, amount of yeast, concentration of glucose, pH
• As temperature increases up to 40 degrees Celsius


  Rate of respiration increases
• Beyond 40 degrees Celsius

  Rate of respiration decreases
• Aerobic respiration


  Chemical reactions in cells that use oxygen to break down nutrient molecules to release energy
• Anaerobic respiration


  Chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
• Anaerobic respiration releases much less energy per glucose molecule than aerobic respiration
• Anaerobic respiration in yeast

  Glucose to give alcohol and carbon dioxide
• Anaerobic respiration in muscle cells during vigorous exercise

  Glucose to give lactic acid
• During vigorous exercise


  Anaerobic respiration occurs to provide necessary energy
• Lactic acid builds up in muscle cells


  Can cause cramps, muscle fatigue, etc.
• After exercise


  Heart rate continues to be fast to transport lactic acid from muscles to liver
• At the liver


  Lactic acid reacts with oxygen and produces carbon dioxide and water
• Oxygen debt


  Temporary shortage of oxygen during vigorous exercise
• Comparison of aerobic and anaerobic respiration

  • Oxygen needed in aerobic, not needed in anaerobic

  Products of aerobic: CO2 and H2O, products of anaerobic in animals: lactic acid, products of anaerobic in yeast: CO2 and ethanol

  A lot of energy released in aerobic, little energy released in anaerobic