Virtual Cellular Respiration Lab Report

Cellular Respiration Lab Introduction : Cellular respiration is the release of energy from organic compounds by metabolic chemical oxidation in the mitochondria within each cell. Cellular respiration involves a series of enzyme-mediated reactions. The equation below shows the complete oxidation of glucose. Oxygen is required for this energy-releasing process to occur. C 6 H 12 O 6 + 6O 2 --> 6 CO 2 + 6 H 2 O + 686 kilocalories of energy /mole of glucose oxidized By studying the equation above, you will notice there are three ways cellular respiration could be measured. One could measure the: 1. Consumption of O 2 (How many moles of oxygen are consumed in cellular respiration?) 2. Production of CO 2 (How many moles of carbon dioxide are produced by cellular respiration?) 3. Release of energy during cellular respiration. In this lab, we will measure rates of cellular respiration by measuring the amount of CO 2 produced by crickets and a mouse, at various temperatures. It is important to keep in mind that crickets are ectotherms while mice are endothermic. Because the organisms we are studying have different masses, we will need to take this into account and convert our data into respiration rates per gram. We will also compare rates of cellular respiration between mice and rats to see how the size of an organism affects its rate of cellular respiration. *Please note that all of the animals used in this experiment were kept safe and comfortable during the recording of the videos. Lab Objectives: ● Calculate the rate of cell respiration from experimental data. ● Relate gas production to respiration rate. ● Test the effect of temperature on the rate of cell respiration in different organism. Part 1 Research Question: How does temperature affect the rate of cellular respiration in ectotherms vs endotherms? Write an experimental hypothesis: As the temperature decreases, the metabolic rate of the ectotherm will decrease while the metabolic rate of the endotherm will increase because ectotherms rely on environmental temperature while endotherms rely on cellular respiration. Procedure: 1. View each of the following videos. As you view the videos, record your data in Table 1. ● Crickets 12 – 15 o C ● Crickets 24 – 26 o C

● Crickets 31 – 37 o C ● Mouse 12 – 15 o C ● Mouse 24 – 26 o C ● Mouse 31 – 37 o C Table 1: Initial and Final amounts of CO 2 produced by crickets and mice in timed trials at three different temperatures Organism Temp o C Initial amt of CO 2 (ppm) Final amt of CO 2 (ppm) Total amt of CO 2 produced (ppm) (Final – initial) Length of trial in minutes Crickets 12 - 15 582 1263 681 23.37 Crickets 24 – 26 826 3007 2181 23.33 Crickets 31 – 37 737 4884 4147 23.38 Mouse 12 – 15 765 7041 6276 13.28 Mouse 24 – 26 640 3975 3335 13.15 Mouse 31 - 37 612 4714 4102 9.87 2. When referring to gasses, the unit “parts per million (ppm) is often used. Because the air in the tank where the organisms are located during the experiment is a mixture of different gases (O 2 , CO 2 and other gases), the CO 2 data collected in ppm allows us to determine the proportion of the total gas molecules in the tank that is made up of carbon dioxide molecules. We will now convert our data from ppm to mL of CO 2 produced. To do this you need to perform the following calculations: With gasses, parts per million (ppm) is defined as the number of CO 2 molecules in a sample of 1 million total gas molecules. In other words, the proportion of the total gas molecules (remember, air is a mixture of different gasses) that is made up by the carbon dioxide molecules. For example, a sample of 1000 ppm CO 2 is equal to : 1000 CO 2 _______ = 0.001 1,000,000 total molecules This is the percentage of the total number of gas molecules in the mixture made up by the CO 2 . The volume of the tank is 32 L or 32,000 mL. Since we know what percentage of the total gas mixture in the tank is CO2, we can calculate what part of the total volume of the tank is made up of CO 2 molecules. In this example: 0.001 x 32,000 mL = 32 mL of CO 2 Using the above example as a guide, convert your data for CO 2 produced from ppm to mL and record your values in Table 2.

Part 1 – Conclusion Questions: 1. Describe how respiration rates are affected by temperature in crickets. As temperature increases in crickets, respiration rates also steadily increase. From the results we can see that crickets have a higher cellular respiration rate in warmer temperatures because they have the highest respiration rates between 31-37 °C. The lowest cellular respiration rate is in cold temperatures which is between 12-14 °C. 2. Describe how respiration rates are affected by temperature in mice. When a mouse is exposed to colder temperatures the respiration rate is higher than when exposed to the other two temperatures. At the lowest temperature between 12-14 °C, the mouse had the highest cellular respiration rate. The rate dropped over the next two temperature intervals and from this we can infer that the mouse is producing more carbon dioxide at lower temperatures. 3. Compare how respiration rates are affected by temperature in crickets vs mice. Crickets have very low respirations rates in low temperatures and even in high temperatures, the rate does not increase by too much. However, mice have very high rates at low temperatures and even though the rates fall in higher temperatures, their cellular respiration rates are fairly high compared to the crickets.

4. Explain why changes in temperature affect the crickets’ rate of respiration in a different way than the mice. Crickets have lower respiration rates because they produce less carbon than mice do. Because they produce less carbon that in turn affects their respiration rate and respiration rate per gram. Another reason could be because crickets are cold blooded creatures which mean that they take on the temperature of their surroundings. The cold generally tends to slow down the reactions. Mice are warm blooded so their regular respiration rate is higher than mice. 5. What did you notice in general about the differences in the rates of respiration in crickets (ectotherms) vs mice (endotherms)? Explain. As seen in the graph, the rates of respiration in crickets increased as the temperatures increased and in mice the rate of respiration did not seem to have any relationship with temperature because it was fluctuating. This shows that the crickets’s respiration rates are dependent on their environment and that the mice do not rely on their environments to increase the rate of respiration. Part 2 Research Question: How does size affect the rate of cellular respiration in mice vs rats? Write an experimental hypothesis: If the size of the rat is bigger than the mouse then the cellular respiration rate will be lower than that of the mouse. Procedure: 1. View each of the following videos. As you view the videos, record your data in Table 4. ● Mouse 24 – 26 o C ● Rat 24 – 26 o C Table 4 – Initial and Final amounts of CO 2 produced by a mouse and a rat in timed trials at 24 – 26 o C Organism Initial amt of CO 2 (ppm) Final amt of CO 2 (ppm) Total amt of CO 2 produced (ppm) (Final – initial) Length of trial in minutes Mouse 640 3975 3335 13.15 Rat 809 7384 6575 14.40 2. As you did in Part 1, convert your data for CO 2 produced from ppm to mL and calculate the respiration rate per minute. Record your values in Table 5. Table 5 - Amounts of CO 2 produced by a mouse and a rat in timed trials at 24 – 26 o C