Unit 1.2

• Aerobic respiration


  1. Blood carries glucose and oxygen to the cells

  2. Glucose and oxygen diffuse into cells

  3. Glucose reacts releasing stored energy

  4. Energy released as ATP
• Aerobic respiration is a series of enzyme-controlled chemical reactions in the mitochondria of cells
• Aerobic respiration releases energy as ATP
• Aerobic respiration releases carbon dioxide and water
• Investigating respiration in germinating peas


  1. Peas respire releasing heat, temperature goes up

  2. Peas boiled, temperature still increases slightly due to respiring microbes

  3. Boiled and disinfected peas, temperature does not increase as no respiration
• Anaerobic respiration


  1. Shorter series of enzyme-controlled reactions

  2. Partially breaks down glucose

  3. Releases some energy

  4. Can occur without oxygen
• Anaerobic respiration


  Produces lactic acid and less ATP than aerobic respiration
• Oxygen debt must be paid back when oxygen is available to break down lactic acid
• Alveoli


  • Good blood supply
  • Large surface area
  • Thin walls
  • Moist lining
• Inspiration


  1. Intercostal muscles contract lifting ribs up and out

  2. Diaphragm contracts and flattens

  3. Chest cavity increases in volume and decreases in pressure, air is sucked in
• Expiration


  1. Intercostal muscles relax and ribs move down and in

  2. Diaphragm relaxes and domes up

  3. Chest cavity decreases in volume and increases in pressure, air is forced out
• Inspired air contains 21% oxygen, expired air contains 16% oxygen
• Inspired air contains 0.04% carbon dioxide, expired air contains 4% carbon dioxide
• Expired air is saturated with water vapour
• Limewater test can be used to detect carbon dioxide in expired air
• Cilia and mucus


  • Cilia beat and move mucus up trachea to be swallowed
  • Mucus traps particles and bacteria
• Smoking paralyses cilia and clogs mucus
• Effects of smoking


  • Tar contains carcinogens that cause lung cancer
  • Nicotine is addictive
• Emphysema


  • Smoking destroys lung tissue
  • Reduces surface area for gas exchange
  • Patients struggle to get enough oxygen
• Bell jar model of respiratory system


  Limitations: Balloons for lungs don't fill jar, bell jar for ribs doesn't move, rubber sheet pulls down further than flat
• Huff and puff apparatus


  1. Inspired air drawn through limewater, slightly cloudy

  2. Expired air bubbled through limewater, very cloudy
• Mitochondria are responsible for producing energy through respiration.
• The cytoplasm is where most chemical reactions take place, including protein synthesis.
• The nucleus contains the genetic material (DNA) which controls all cellular activity
• The process of cellular respiration involves the breakdown of glucose into carbon dioxide and water, releasing energy in the form of ATP molecules.
• Glycolysis occurs in the cytoplasm and produces two pyruvate molecules from one glucose molecule.
• Ribosomes are the site of protein synthesis.
• Pyruvate oxidation takes place in the mitochondrial matrix and converts pyruvate into acetyl CoA, which enters the citric acid cycle.
• Chloroplasts contain chlorophyll and are found only in plant cells
• Ribosomes are involved in protein synthesis
• Chloroplasts contain chlorophyll and are involved in photosynthesis.
• Vacuoles store water, waste products or pigments
• Cellular respiration occurs in three stages: glycolysis, Krebs cycle, electron transport chain.
• Pyruvic acid enters mitochondria to undergo oxidative phosphorylation, resulting in the production of more ATP molecules.
• Glycolysis takes place in the cytosol and produces two pyruvate molecules from one glucose molecule.
• Oxygen is required for aerobic respiration to occur.
• Lysosomes contain digestive enzymes that break down waste materials inside cells.
• Krebs cycle takes place in the mitochondrial matrix and breaks down pyruvate to produce NADH, FADH2, and CO2.
• The nucleus contains genetic material (DNA) that controls cell activity
• Mitochondria produce ATP through aerobic respiration