Introduction: Aerobic respiration is the process by which glucose and oxygen produce carbon dioxide, water and large amounts of energy through the action of mitochondrial enzymes. Plants can also perform respiration in addition to photosynthesis. Today's experiment is to detect the aerobic respiration of peas with DrDAQ. In this experiment, it can be seen that the oxygen content in the sealed container decreases with time due to the oxygen consumption of the peas.
Equipment required: PC; DrDAQ data logger; oxygen sensor; 2 liter beaker; 100 ml beaker; beehive rack; sink container; water; peas - soak a little thyme in water overnight to kill bacteria; cotton handkerchief or cotton wadding.
Experimental setup:
1. Connect the DrDAQ data logger to the parallel port (or USB if using a USB to parallel port adapter).
2. Install the oxygen sensor on the honeycomb stand. Use a little bit of glue to help hold it in place. Run it to connect the wires through the center hole of the honeycomb stand.
3. Fill the sink to a depth of about 3 cm at room temperature and place the honeycomb stand in the sensor. Plug the sensor's connecting wires into an external socket on the DrDAQ.
4. Place a piece of tissue or a piece of lint on the bottom of a 100 ml beaker and place 10 ounces of peas. Place this beaker in the water next to the honeycomb stand.
5. Now place the 2 liter beaker on the honeycomb stand and 100 ml beaker and place in water to seal it in the air.
The experiment should be in a thermostatically controlled room or laboratory. It should not be in a place with a large temperature difference, such as: suddenly opening/closing windows or turning on/off the air conditioner will cause room temperature instability.
conduct experiment:
1. Load the PicoLog and configure it to collect oxygen sensor readings for three days per minute (4320 samples). This is actually not the data you need to keep, but it will let you know when to start recording real data.
2. Set it to start recording. Regular reference to oxygen content over the next two or three days. During this time, the peas should start to germinate, breathing will begin and the oxygen content will drop. At this stage, stop recording and discard the data.
3. Reconfigure the software to collect the oxygen sensor readings every minute for two days (2880 samples) to set it to start recording. A chart showing % oxygen versus time when the data record is complete.
4. Ideally, it will also investigate how the temperature of the peas and their environment changes as the respiration occurs (should rise). However, what is difficult to achieve is to provide a sealed environment. Perhaps the best way is to place the peas, oxygen sensor and temperature sensor in an upward vacuum bottle and place in the water. The external temperature will also be monitored. Obviously some of the energy will be transferred through the water, but the increase in the temperature of the peas and their environment in the external environment should be obvious.
Extended research:
The extension of the basic experiment may be to place the trough, honeycomb frame, beaker, peas, etc. into a thermostatically controlled heated water bath or on a hot plate, and observe whether the temperature affects the respiration rate, thus absorbing oxygen at a rate. The temperature can reach about 40 °C.
A further investigation may be to see if there is any effect on the light intensity, illuminate the peas with a light bulb, and additionally record the light level. Energy-saving fluorescent lamps should be used because fluorescent lamps are rarely heated. The readings should then be taken from outside the oxygen sensor connected to the DrDAQ and the readings taken from the DrDAQ's on-board light level sensor.
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