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Respiration, ATP and respiring seeds
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Every living cell respires all the time. Respiration makes ATP, which cells use as their energy supply.
Respiration and ATP
Respiration is a series of chemical reactions in cells that release energy from glucose.
The energy is used to make ATP. ATP then provides energy for cells, for example for muscle contraction, active transport and building large molecules.
The energy is used to make ATP. ATP then provides energy for cells, for example for muscle contraction, active transport and building large molecules.
Aerobic and anaerobic
Aerobic (with oxygen): glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2 → 6CO2 + 6H2O
Anaerobic (without oxygen) releases much less energy:
Animals: glucose → lactic acid
Plants and yeast: glucose → ethanol + carbon dioxide
C6H12O6 + 6O2 → 6CO2 + 6H2O
Anaerobic (without oxygen) releases much less energy:
Animals: glucose → lactic acid
Plants and yeast: glucose → ethanol + carbon dioxide
Investigating respiring seeds
Heat: put germinating peas in a vacuum flask with a thermometer. A second flask holds boiled (dead) peas as a control. Rinse both in disinfectant so microorganisms do not respire. The temperature rises only in the flask of living peas.
Carbon dioxide: hydrogencarbonate indicator changes from red (or orange) to yellow as carbon dioxide increases. Limewater turns milky.
Carbon dioxide: hydrogencarbonate indicator changes from red (or orange) to yellow as carbon dioxide increases. Limewater turns milky.
Why are the peas in the control flask boiled?
- Boiling kills the peas, so they cannot respire.
- Any temperature change in the control is then not caused by respiration of the peas.
Answer: So they are dead and cannot respire, making a fair comparison.
Respiration releases energy to make ATP, which powers cell processes. Aerobic: C6H12O6 + 6O2 → 6CO2 + 6H2O. Anaerobic in animals gives lactic acid; in plants and yeast it gives ethanol and carbon dioxide. Respiring seeds release heat and carbon dioxide.
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