The mensuration of cell respiration of plants based off of the amount of O 2 produced Abstract: In this experiment, the rate of reaction for plant cell respiration will be measured, based upon the amount of O 2 consumed in order to form CO 2 based along the standard equation defining the breakdown of glucose and oxygen into carbon dioxide, water, and free energy. The amount of O 2 used will be measured by a re spirometer, an apparatus that functions based off the the common ideal-gas principles of the relationship between pressure, temperature, number of molecules, and volume of gas. Dormant and germinating plant seeds will be observed, and their rates of cellular respiration calculated for two different temperatures to note the effects temperature has upon catabolic molecular reactions. Introduction: Cellular respiration is the act of releasing energy from organic compounds by metabolic chemical in the mitochondria of a cell.
A common molecule used in respiration is glucose. The oxidation of glucose is an aerobic one, meaning that it requires oxygen in order to occur. The equation below shows what is happening on the molecular level. C 6 H 12 O 6 + 6 O 2 -- -> 6 CO 2 + 6 H 2 O + 686 KCal / mole of glucose oxidized. This experiment will measure the amount of O 2 by both germinating and non germinating peas, at both 10 degrees and 25 degrees Celsius. The three ways the process of cellular respiration can be measured.
The first way is to measure the amount of O 2 consumption. The second is to measure the a mound of CO 2 produced. The third is to measure the amount of energy released through respiration. The amount can of the gasses produced can be measured using a re spirometer. A re spirometer utilizes the principle of the ideal gas law, which states that PV = nRT In that P is the pressure of the gas in atmospheres, V is the volume of the gas in liters, n is the number of molecules of gas in moles, R is the gas constant, and T is the temperature of the gas in Kelvins.
Naturally, since this is a catabolic process, the reaction will happen at a faster rate the higher the temperature is. The CO 2 produced during respiration will in this experiment be removed by KOH to form solid k allium carbonate (potassium carbonate) based on the reaction: CO 2 + 2 KOH -- -> K 2 CO 3 + H 2 O Since the CO 2 is being removed from the cellular respiration reaction due to its reaction with KOH, the change in the volume of gas in the re spirometer will be directly proportionate to the amount of O 2 consumed. This is because there will be no alteration in the temperature, rather only in the gas pressure, which is lessened the fewer the number of particles of the gas contained therein. The net change in the gas volume within the tube is a result of the oxygen being converted to carbon dioxide, which then sublimes into k allium carbonate, and thus exhibits no gas pressure.
Materials and Procedure: Six will be obtained, along with 2 baths, one at room temperature, 25 degrees C, and the other at 10 degrees Celsius. The cooler bath will be maintained in temperature by the addition of ice so that the conditions remain the same. A 100 mL graduated cylinder will be filled with 50 mL of water. Then, 25 germinating peas will be added to determine the volume of the water displaced, which was found to be 2 mL.
The peas will then be removed and set aside, for use in re spirometer one. The cylinder will be refilled with 50 mL of water, 25 dried peas, and then sufficient glass beads to displace an equal amount of water as the germinating peas. The beads will be removed, and then placed aside like the first for use in the second re spirometer. Re spirometer three will be filled with glass beads equal in volume to the displacement value, 2 mL. The same pattern will be repeated for four, five, and six as used for one, two, and three, respectively.
The six will be assembled with six phials, each with a stopper and attached pipette. The pipette will be bonded to the stopper so that it doesn't slip nor let any gas escape through the opening in the middle of the stopper. Absorbent cotton will be placed in the bottom of the phial, which will be saturated with a 15% solution of KOH. The phial will be wiped so that no KOH gets on the inside.
A small wad of dry, non-absorbent cotton will be placed on top of the absorbent cotton. The first set of three, 1, 2, 3, will be filled with the respective germinating peas, dry peas+ glass beads, glass beads, will be closed with the stopper, and placed in over a sling of masking tape attached to each side of the 10 degree Celsius water bath to hold the pipette out of the water during an equilibrium period of seven minutes. The second set, 4, 5, 6, will be filled with their respective contents and placed in the same manner as the first set in the other bath of 25 degree Celsius water. After the equilibrium period is spent, all six will be immersed in their water baths entirely.
Water should enter the pipettes for a short distance, and then stop. After this immersion, the should not be molested for the rest of the experiment. Another equilibrium of period will begin, this one is for 3 minutes. Afterwards, the initial position of water will be recorded every 5 minutes for a period of time of 20 minutes. Results: Discussion: The data obtained were mostly meaningless, because of several things. Firstly, the only non-zero data obtained were from from the glass beads, and the germinating peas at 25 degrees.
This means that most of the rates were indeterminate because there was no slope for the lines in these cases. Also, it is relatively unlikely that glass beads undergo cellular respiration, and thus the data for those two control groups are flawed, as glass beads are not alive. Thirdly, although plants undergo respiration, it is in the form of photosynthesis, and happens to be the EXACT OPPOSITE equation written above, meaning that the plants produce glucose and oxygen from energy, water, and carbon dioxide. This shows that the last nonzero data are useless as well.