Flashcards · 0610 · Topic 12

Respiration flashcards

15 cards on Topic 12, subtopics 12.1 to 12.3. Pick a subtopic or study them all.

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Seven uses of energy in the human body: Muscle contraction, protein synthesis, cell division, active transport, growth, passage of nerve impulses, maintenance of a constant body temperature.
Respiration v breathing: Chemical energy release in cells v air moving in and out of the lungs.
Release v produce (energy in respiration): Energy is released, never produced or made.
Effect of temperature on respiration in yeast: The rate rises towards an optimum, then falls and almost stops at high temperatures, because the enzymes controlling respiration are denatured. (The enzymes are denatured, not the yeast.)
Measuring the rate of respiration of yeast at different temperatures: Keep yeast and glucose volumes and concentrations the same, equilibrate in a water bath, then count bubbles of carbon dioxide per minute (or measure gas volume). Repeat and take a mean.

Aerobic respiration: The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
Word equation for aerobic respiration: glucose + oxygen → carbon dioxide + water
Balanced equation for aerobic respirationExtended: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
How many oxygen molecules are needed to respire 2 glucose molecules aerobically?Extended: 2 × 6 = 12.

Anaerobic respiration: The chemical reactions in cells that break down nutrient molecules to release energy without using oxygen.
Word equations for anaerobic respiration in yeast and in muscles: Yeast: glucose → alcohol + carbon dioxide. Muscles (vigorous exercise): glucose → lactic acid.
Energy released by anaerobic compared with aerobic respiration: Anaerobic respiration releases much less energy per glucose molecule.
Balanced equation for anaerobic respiration in yeastExtended: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
Cause of the oxygen debtExtended: During vigorous exercise muscles respire anaerobically, so lactic acid builds up in the muscles and blood.
How the oxygen debt is removed after exerciseExtended: A fast heart rate continues, carrying lactic acid to the liver. Deeper, faster breathing continues, supplying oxygen. In the liver, lactic acid is broken down by aerobic respiration.