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Respiration

Respiration. BIOLOGY 2. Energy Release. Every cell needs energy to keep it alive. This energy comes from glucose. This sugar is broken down by a series of reactions called respiration . These reactions are speeded up by enzymes acting as biological catalysts.

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Respiration

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  1. Respiration BIOLOGY 2

  2. Energy Release Every cell needs energy to keep it alive. This energy comes from glucose. This sugar is broken down by a series of reactions called respiration. These reactions are speeded up by enzymes acting as biological catalysts.

  3. This is the usual type of respiration seen in humans - it uses oxygen. The reactions of respiration take place in tiny structures called mitochondria (singular: mitochondrion) and they are referred to as the ‘power-houses’ of the cell because they produce the cell’s energy. Mitochondrion Aerobic respiration

  4. Higher Anaerobic Respiration Respiration can happen without oxygen. This process is called anaerobic respiration. Only a portion of the energy contained in the glucose is released.

  5. Higher Anaerobic respiration in yeast cells When yeast respires without the presence of oxygen (anaerobic respiration) it produces ethanol (alcohol). This process is called fermentation. Glucose CO2+ ethanol +H2O +EGNI

  6. Higher Anaerobic respiration in the muscles When muscles work hard and the oxygen level decreases in the cells, they can respire anaerobically for a short time to enable them to keep going: glucose lactic acid + energy

  7. Higher Disadvantages of Anaerobic Respiration • It doesn’t release all the energy trapped in the glucose. • Ethanol is toxic to cells. • Lactic acid builds up in muscle cells and causes cramp.

  8. During physical exercise, acid lactic builds up in the muscles and it needs to be broken down. The body needs oxygen to do this and so we breathe deeper and quicker. In a way, we are paying this oxygen back. The name given to the ‘loan’ is oxygen debt. O2 Higher Oxygen Debt

  9. Practical Work Energy release from respiring seeds. The peas in the three flasks below have been treated differently:

  10. thermos flask metal case 12 1 11 2 10 9 3 temperature probes 8 4 7 5 6 clock Flasks of peas A B C computer boiled pea seeds in disinfectant fresh pea seeds boiled pea seeds temperature datalogging interface time A computer can be used to prove that respiring peas release energy in the form of heat.

  11. Results fresh pea seeds boiled pea seeds boiled pea seeds in disinfectant

  12. Question Why do the boiled peas that haven’t been disinfected cause a temperature increase?

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