Cell Respiration Lab Report PDF

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Michael Williams Professor Marlena Koper Biology 106-F Lab Investigation Write Up Due: March 2019 Ectotherm’s and Cellular Respiration: Comparing the Respiration Rates of Acheta Domesticus in Different Temperatures Introduction: This study was completed in order to determine how changes in temperature affect the respiration rate of Acheta domesticus (house crickets). House crickets are ectotherms, which means that they use energy from the environment and behavioral adaptations in order to regulate their body temperatures. This differs from endotherms (ex. humans) which use metabolic energy in order to maintain a constant interior body temperature. Ectotherms are sometimes referred to as cold blooded organisms because they move slow when their environment is cold. In our study there will be three different temperatures that are measured, and the control will be the metabolic rate of crickets at room temperature. The same crickets will then be exposed to a warmer environment (about 35 degrees Celsius) and then finally a colder environment (about 15 degrees Celsius). Cellular respiration is how an organism breaks down carbohydrates in order to produce energy and can be represented by the equation C6H12O6 + 6O2 —> 6CO2 + 6H20 + ATP + Heat. In order to measure metabolic rate (the rate at which cellular respiration occurs) either heat production or carbon dioxide production can be measured. Recently a mathematical equation has been derived which is able to connect both size of an organism and surrounding temperature to metabolic rate (Jonsson and Audrey 2017). Based on this previous research and the fact that Acheta domesticus are ectotherms, it is predicted that as the temperature increases, so will the production of carbon dioxide and therefore so will the metabolic rate. Methods: Thirty-six cricket respiration chambers each had three crickets placed inside. The mass of the crickets combined was found using an Ohaus top loading electrical balance. The crickets were given time to acclimate to their chamber before the study proceeded in order to allow their metabolic rate to adjust from the stock container. A carbon dioxide sensor was then placed in each of the respiration chambers to measure the amount of carbon dioxide that was produced as the study ran for three minutes. Six extra respiration chambers had thermometers in them held by a rubber stopper, and the temperature was taken and recorded. When the three minutes had passed, the carbon dioxide sensors were removed. Six water baths of about 35 degrees Celsius was prepared, and each bath had six cricket respiration chambers were placed into the water baths so that the water almost reached the neck of the chamber. The crickets were allowed time (about three minutes) to acclimate to the new environment. After this, the temperature was recorded from the six temperature chambers (each in a water bath) and the carbon dioxide sensors were placed in the chambers and the study ran for three minutes. The sensors were then removed from the chambers, and the crickets were removed from the water bath.

Six ice baths of about 15 degrees Celsius was prepared and all of the respiration chambers were placed into the new environment, for which they were given time to acclimate. It is important to do the cold environment last as the crickets may experience a shock which will leave them motionless for some time, and the same crickets are used for each trial. After about three minutes the temperature was recorded from each ice bath, the carbon dioxide sensors were placed in the respiration chambers, and the study ran for three minutes. After this, the crickets were removed from their chambers and placed into the used cricket bin. Using the temperature, mass of crickets and the carbon dioxide production measurements, the rate of carbon dioxide production and metabolic rate of the crickets were found, and an ANOVA (α=0.05) was run to determine the significance of the results. Analysis: Each of the six trials had six respiration chambers, totaling thirty-six chambers in each of the environments. Due to equipment malfunction, trial two and five both had only five respiration chambers, bringing the total down to thirty-four chambers. The respiration rate averages were always higher in the 35-degree Celsius environment compared to the 15-degree Celsius environment. The trend can be seen in Figure 1, which generally shows that the warmer the temperature the higher the respiration rate. The average respiration rates for the 15-degree environment, 25-degree environment and 35-degree environment were 1.171±0.407 ppm/sec/gram, 1.967±0.433 ppm/sec/gram, and 3.071±0.434ppm/sec/gram, respectively. A single factor ANOVA test (α=0.05) determined that the data was significant (p ¿ .003). The ANOVA rejected the null hypothesis (H0) that there was no difference in respiration rate. Therefore, we have convincing evidence to conclude that the true mean respiration rates of Acheta domesticus in the three environments (15, 25, and 35 degrees Celsius) were significantly different.

Respiration Rate (ppm/sec/gram)

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Trial Respiration Rate 25 degees Celsius (ppm/sec/gram) Respiration Rate 35 degees Celsius (ppm/sec/gram)

Respiration Rate 15 degees Celsius (ppm/sec/gram)

Figure 1: The respiration rate of the crickets was calculated at all three temperatures and then graphed. The data represents that of the of six water/ice baths.

Discussion: This study was conducted in order to discover how temperature affected the respiration rate of Acheta domesticus (house crickets). The results show statistically significant evidence that as the temperature increases, so does respiration rate. The control for the experiment was respiration rate at room temperature (25 degrees Celsius), and then two other environments of warm (35 degrees Celsius) and cold (15 degrees Celsius) were tested. The mean respiration rates increased as the temperature did. The respiration rate increased due to the fact that Acheta domesticus are ectotherms. Similar relationships between temperature and respiration rates using other ectotherms (reptiles, amphibians and fishes) have been found and published (Gillooly et. al. 2016). The ectotherms, often called cold-blooded, organisms use their surroundings in order to regulate their body temperatures. The mean respiration rates were analyzed using a single factor ANOVA test ( α=.05). The results of this test did confirm that the difference of all three respiration rates were significant, rejecting the null hypothesis (H0) that the respiration rates did not differ at different temperatures. It was therefore confirmed that, with 95% certainty, the different temperate environments had different respiration rates in Acheta domesticus. The concern of respiration rates in insects is steadily growing as Earth’s biodiversity continues to be threatened. Research has been continuing on many insects, including Acheta domesticus, and how they adapt to temperate changes as they are necessary to keep a stable ecosystem (Lachenicht et. al. 2010). Continuing research on respiration rates may help in eventual and current invasive species outbreaks and movement, along with the risks and distributions of diseases. In summary, it was determined that as environmental temperature increased, so did respiration rate in Acheta domesticus, and it is important to continue learning what we can about the respiration rates in insects as the benefits are abundant.

References: Gillooly, James F., Gome, Juan Pablo., Rong, Yue, et. al.. (2016). Body mass scaling of passive oxygen diffusion in endotherms and ectotherms. Proceedings of the National Academy of Sciences. 113(19):5340-5345. Lachenicht, M.W., et. al.. (2010). “Effects of Acclimation Temperature on Thermal Tolerance, Locomotion Performance and Respiratory Metabolism In Acheta domesticus L. Journal of Insect Physiology. 56(7):822-830. Johnsson, Tomas., Dussutour, Audrey. (2017). Metabolic Theory Predicts Animal self-thinning. Journal of Animal Ecology. 86 (3): 645-653....