Life Sciences, Metabolism, Plant Physiology / Principles and Exploration
Cellular respiration and oxygen use — principles and investigation
The amount of oxygen consumed by germinating seeds can be an indicator of changes in cellular respiration. Compare oxygen reduction over time by changing seed mass, temperature, condition, and initial oxygen amount. Read about total consumption, respiration per unit mass, and when oxygen is sufficient and when it is insufficient.
How does it work?
If there is enough oxygen, the speed doubles with a 10 °C rise, and the total speed is proportional to mass. When oxygen becomes scarce, the rate of consumption decreases and it becomes non-negative. Boiled seeds are 0.
v₀ = k·mass·2^((T−20)/10) · Q10=2
Try this investigation
- Compare sprouted seeds and boiled seeds. CO₂ is absorbed into the separated KOH, and when oxygen is consumed, the blue ink in the scale moves toward the seed.
- Keep the mass, temperature, and initial oxygen the same, and run and record germinated and boiled seeds, respectively.
- Compare the initial speed when the temperature is increased to 30 °C and the speed when the mass is increased to 4 g. By reducing only the oxygen, we check whether the speed decreases near depletion.
Interpreting your results
Why does the gas volume decrease even though the respiring seeds produce CO₂?
Assume that KOH absorbs CO₂ in a closed respiratory system. The remaining gas loss represents oxygen consumption. Boiled seeds are the control group with a respiration rate of 0.
Assumptions and limitations
It is a virtual model that assumes constant temperature, sealing, no leakage, and complete absorption of CO₂ by KOH. k=0.02 mL/(g·s), Q10=2 is used, and below the oxygen amount of 1 mL, the speed decreases in proportion to the oxygen amount. Assume that all initial oxygen is available. The scale moving distance is an explanatory scale and does not cover changes in gas temperature and pressure, actual practice of KOH hazards, and differences/denaturation by species.