Respiration

  1. Respiration - a chemical process where glucose is broken down to release energy to carry out different cellular processes, process of respiration is controlled by enzymes

  2. Uses of energy - 1. Muscle contraction
    2. Protein synthesis
    3. Cell division
    4. Active transport
    5. Growth
    6. The passage of nerve impulses
    7. The maintenance of a constant body temp

  3. Effect of temp on respiration investigation - yeast is a living organism so it can be used to investigate how its respiration is affected by temperature
    1. Add yeast and glucose solution to a test tube.
    2. Place test tube in a water bath of 30C
    3. Add a drop of methylene blue to the test tube and start the timer. Shake for 10 seconds
    4. Record how long it takes for methylene blue to turn colorless. The faster the color changes the faster the rate of respiration
    5.  Repeat the experiment at different temperatures with water baths of different temps
    6. Find the rate of respiration at each temperature.
    Independent variable(changing factor): temperature
    Dependant variable(measuring factor): time taken for color change can be converted to  rate of resp. with formula rate = 1/time
    Control: amt. of methylene blue, amt of yeast suspension, conc. of glucose, pH
    *as temp increases, rate of respiration also increases until a certain point afterwhich the rate will decrease 

  4. Respiration can take place - aerobically (with oxygen) or anaerobically (without oxygen)

  5. Aerobic respiration - chemical reactions in cells that use oxygen to break down nutrient molecules (glucose) to release energy. The word equation: glucose + oxygen —> carbon dioxide + water. Balanced chemical equation: C6 H12 06 + 602 —> 6CO2 + 6H20

  6. Anaerobic respiration - chemical reactions in cells that break down nutrient molecules (glucose) to release energy without using oxygen. Releases much less energy per glucose molecule than aerobic respiration. 

  7. Anaerobic respiration in yeast - process used in breadmaking, brewing. glucose —> alcohol + carbon dioxide. Balanced equation: C6 H12 06 —> 2C2 H5 OH + 2CO2 (carbon dioxide and ethanol)

  8. Anaerobic respiration in animals - When we do strenuous exercise, muscles deman more energy. The energy needed cannot be provided only by AR because muscles may not be receiving oxygen quick enough. Therefore, ANR takes place to provide the necessary energy. breaks down glucose without oxygen and produces lactic acid, a toxic waste product. Less energy is produced when glucose is broken down anaerobically.
    word equation for ANR in muscles during vigorous exercise is: glucose —> lactic acid.

  9. Lactic acid - builds up in muscle cells and blood, can be toxic to muscle cells (eg. cramps, muscle fatigue) so needs to be removed, causes oxygen debt

  10. Oxygen debt - temporary shortage of oxygen during vigorous exercise is known as oxygen debt. oxygen debt is removed after exercise, limited to: 1. continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver 2. continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid 3. aerobic respiration of lactic acid in the liver: In the liver, lactic acid reacts with oxygen and produces carbon dioxide and water. (aerobic respiration since LA is nutrient molecule)