section 4 - respiration and gas exchange

• Aerobic respiration


  Respiration that occurs in mitochondria and produces a lot of ATP
• Aerobic respiration


  1. Word equation

  2. Balanced chemical equation
• Anaerobic respiration


  Respiration that produces little ATP, occurs in animal muscle cells
• Anaerobic respiration in plants/fungi


  Called fermentation and used in baking
• Respiration experiments


  1. Use germinated seeds and boiled (dead) seeds

  2. Measure colour change of hydrogencarbonate indicator

  3. Germinated seeds respire, change colour to yellow

  4. Boiled seeds do not respire, no colour change

  
• Respiration experiments


  • Independent variable: living organism - dead/alive
  • Dependent variable: colour change caused by CO2
  • Control variables: volume of seeds, indicator, type of seeds, temperature, time

  
• Respiration increases temperature


  • Germinating seeds release heat, temperature increases
  • Boiled seeds do not respire, no heat released, temperature does not increase

  
• Respiration experiments on temperature


  • Independent variable: dead/alive seeds
  • Dependent variable: temperature change
  • Control variables: time, volume of seeds, type of seeds

  
• Gas exchange


  Movement of gases by diffusion
• Ventilation


  Moving air in and out of lungs
• Breathing in/inhalation


  1. Ribs move up and out

  2. Diaphragm contracts and flattens

  3. Intercostal muscles contract

  4. Volume of air in lungs increases

  5. Pressure in lungs decreases
• Breathing out/exhalation


  1. Ribs move down and in

  2. Diaphragm becomes dome-shaped and relaxes

  3. Intercostal muscles relax

  4. Volume of air in lungs decreases

  5. Pressure in lungs increases
• Alveoli


  • Large surface area for quicker diffusion
  • Good blood supply for high concentration gradient
  • One cell thick walls for shorter diffusion distance
  • Permeable walls
• Investigating release of carbon dioxide from breathing


  1. Use limewater or hydrogencarbonate indicator

  2. Flask A: no colour change, inhaled air

  3. Flask B: colour change, exhaled air

  
• Smoking causes lung cancer
• Smoking causes chronic bronchitis
• Smoking causes emphysema