Observing the effect that temperature has on the metabolic rate of ectotherms by measuring the production of CO2. John Upton, BIO 104, Friday Lab
Introduction
Endotherms, like humans (H. Sapiens), maintain a constant body temperature by using metabolic energy. Ectotherms on the other hand rely on the environment around them for their body temperature. Because of this as the temperature decreases, it will be harder for the ectotherm to maintain its metabolic rate, causing it to decrease (Toxopeus et al. 2019).Crickets (A. domesticus) are ectotherms, so when they are exposed to temperature changes, they will demonstrate the effect of temperature on metabolic rate.
Metabolic rate is the rate in which heat is released from breaking down food. Since this is hard to measure, the rate of respiration is used as a measurement instead. This is measured by recording the amount of CO2 produced by the animal. CO2 can be used to represent metabolic rate because it is a product of cellular respiration. Cellular respiration can be used to represent metabolic rate because it is one of the main ways organisms produce energy from food. So as respiration increases or decreases, the metabolic rate will do the same. Because CO2 is a product of respiration, the change in CO2 in the air will represent the change in respiration, therefor the change in metabolic rate.
This experiment looked at the effect that temperature had on the metabolic rate of ectotherms. The change CO2 production of crickets exposed to different temperatures were measures, thereby giving an understanding of the change in metabolic rate. Given the nature of ectotherms, the change should show that as temperatures increase, the metabolic rate will increase as well.
Methods
To start the experiment, a scale was used to weigh the crickets. Once the crickets were weighted, the rate of CO2 at room temperature (approximately 25℃). This was done by placing a CO2 sensors into the top of each cricket container far enough so that no air could enter or escape. After setting up the sensors, a minute was waited, then data (level of CO2 in parts per million per second) begun collecting. After five minutes the data collection was complete and the stop collection button was clicked. After the data was recorded, a line of best fit was placed in the graph and the slope was recorded.
After the results of the room temperature were recorded, the CO2 levels for the warm temperature were recorded next. This was done by filling up a bowl with warm water from the tab as hot as it could produce. The temperature was them measured in degrees celsius.. The cricket containers were placed into the warm water and held down so they would not float and the data was recorded again for five minutes as done previously. After the five minutes the slope of the best fit line was recorded for the warm temperature.
Once the warm temperature was recorded, the CO2 levels for cold temperature were recorded. This was done by filling up a bowl with cold ice water. The cricket containers were placed into the cold ice water and held down so they would not float and the data was recorded again for five minutes as done previously. After the five minutes the slope of the best fit line was recorded for the cold temperature.
Results
Figure 1. Average rate of cricket respiration when exposed to different temperatures.
The average temperature for cold, room temperature, and hot were 8.75 ℃, 23.75 ℃, and 41.25 ℃ respectively. The average respiration rate for cold, room temperature, and hot were 0.2002132772 ppm/s/g, 0.6817211873 ppm/s/g, and 1.045062473 ppm/s/g. On average, as the temperature rose, the respiration rate rose as well.
Discussion
The hypothesis of this lab was if the temperature increased, the metabolic rate would increase as well. There have been studies that have demonstrated the effect that temperature has on respiration rates in ectotherms (Javal et al. 2018, Źagar et al. 2018). Because ectotherms rely on the environment to regulate their body temperature, the warmer the conditions the higher the metabolic rate will be. This is supported in our results of CO2 production. The increase of CO2 levels are representative of an increase of the metabolic rate.
This was clearly demonstrated by our results. As the temperature changes, the CO2 production changed with it. Just like the studies showed, as the temperature decreased, the crickets in our experiment showed a decrease in metabolic rate. As temperature increased, there was an increase in metabolic rate as well.
One way that this study could be improved if done again is by having consistent temperatures for each trial. One question that was brought up as a result of this lab is do other ectotherms share a similar metabolic sensitivity to temperature change. A follow up study that could be done at the end of this study to answer this question is to do it with another ecotherm rather than crickets to see if they have the same sensitivity to temperature change.
Works cited
Javala M, Roquesa A, Rouxa G, Lapariea M. 2018. Corrigendum to “Respiration-based monitoring of metabolic rate following cold-exposure in two invasive Anoplophora species depending on acclimation regime”. Comparative Biochemistry and Physiology, Part A 216: 20-27.
Toxopeus J, Des Marteaux LE, Sinclair BJ. 2019. How crickets become freeze tolerant: The transcriptomic underpinnings of acclimation in Gryllus veletis. Comparative Biochemistry and Physiology – Part D 29: 55–66.
Žagar A, Carretero MA, Marguč D, Simčič T, Vrezec A. 2018. A metabolic syndrome in terrestrial ectotherms with different elevational and distribution patterns. Ecography 41: 1728–1739.
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- Scientific literacy is the knowledge and understanding of scientific concepts and processes required for personal decision making, participation in civic and cultural affairs, and economic productivity. It also includes specific types of abilities.
- I have seen examples of scientific literacy in lab. For lab, we had to find and read a scientific paper to learn and do a presentation on.
- One of the most important things about that learning outcome is that students learn scientific literacy for making personal opinions. These days, a lot of information is provided to us. This makes it so important for us to learn scientific literacy so we can research the topics being presented to us rather than blindly accepting or disregarding information presented to us.
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