The Effects of Temperature on Aerobic Cellular Respiration


Mary Freeman


CU Boulder, Fall 2006


The question of this investigation was does temperature effect the rate of aerobic cellular respiration in organisms. Aerobic cellular respiration involves the breaking of sugars, proteins, carbohydrates, and other molecules with the effect of producing chemical energy in the form of ATP. In the process of aerobic cellular respiration, sugar and oxygen are used, while water, carbon dioxide, and energy are yielded. Respiration is necessary in the function of all cells and is necessary for the continuation of life.

         Temperature can be described as the average kinetic energy of some given group of molecules. As temperature increases, molecules have more motion and activity, and as temperature decreases, molecules have less motion and activity. With this known, it is hypothesized that this change in cellular activity that change temperature does to molecules will alter aerobic cellular respiration in a similar way; such that as the temperature rises, so will the rate of cellular respiration, and as the temperature decreases, so will the rate of cellular respiration.

         To test this hypothesis, the rates of CO2 levels were found for crickets in different temperature environments (room temperature, hot and cold). 5 crickets were placed in a sealed environment at room temperature (a 25C bottle) and a CO2 probe was connected to the environment. CO2 levels were monitored in approximately 20 second intervals for six minutes. The rate of change in CO2 levels was derived from this data, and finally, the rate of change in CO­2 per cricket was determined. This process was repeated in a hot temperature environment (28C) and finally for a cold temperature environment (15C). This entire process was conducted two other times (with different crickets for each trial) and the average rates of changes in CO2 per crickets were determined for all three temperatures. These averages were then compared using a T-test to determine significant trends

         In analyzing the results, all the data points for the first minute of observation were dropped. These data points were not used because they represented the period of time in which the crickets took to become acclimated and adjusted to the new temperature environment. During this one minute period, the respiration rates were always high because the crickets experienced mild panic in acclimating, however, after the first minute, the crickets settled in and the respiration rates began to follow implied trends.

A significant difference was found between the rate of change in CO2 per cricket in the hot environment compared to the room temperature environment (P=.022). This supports the hypothesis because the rate of respiration rose significantly when the temperature was increased. The difference between the rate of respiration in the cold temperature environment and the room temperature rate was also found to be significant (P= .046) which further supported the hypothesis.

         Both the hot temperature data, the cold temperature data supported the hypothesis. As the temperature of the environment rose, so did respiration rates, and when the environment cooled, respiration rates dropped. The temperature altered the cellular activity of the crickets, and thus affected their cellular rates of respiration. While a similar study was conducted in 2004 by Amy Hambrick, she only ran one test trial, and thus was unable to derive any statistical comparisons, and it is thus difficult to compare the results in this experiment with hers. 

         The hypothesis was partially supported by the data; however, flaws could have led to inaccurate trends. Such errors include only monitoring the respiration rates for five minutes, as well as not using enough crickets in the trial. If the experiment were to be repeated, CO2 levels should be monitored for more than 6 minutes. Also, different organisms should be tested.