Cellular Respiration Lab Sam Larkey, Lynette Santhakumar, Amy Hu, Dylan Flynn

Problem : Does the temperature of pea seeds affect the rate of cellular respiration? How will we design and conduct an experiment to explore the effect of temperature on the oxygen consumption of germinated pea seeds? Background : All living systems and organisms require free energy and matter to maintain order, grow, and reproduce. Cellular respiration converts the chemical energy in organic molecules into ATP. Glucose may be oxidized completely through aerobic respiration if sufficient oxygen is available (C6H12O6 + 6O2 → 6H2O + 6CO2 +energy). To measure the rate of the consumption of O2, we will monitor the pressure changes inside a respirometer. Physical laws pertaining to the properties and behaviors of gases must be considered to monitor pressure changes due to temperature. Hypothesis : We predict germinating peas will consume more O2 than non- germinated peas. Also, we predict that the rate of cellular respiration will increase as temperature increases until the proteins involved reach a point of denaturation.

Procedure : 1. Set up 3 test tubes as directed in the original lab procedure (germinated, non-germinated w/glass beads, and glass beads; all with KOH, cotton, etc.) 2. Cut out 3 evenly spaced crosses in a piece of square cardboard to serve as test tube holders 3. Place cardboard over a beaker filled with room temperature water; insert test tubes into holes and incubate for 10 minutes with plastic tubings detached 4. Perform trial by connecting plastic tubings to each rubber stopper connector and collect data for approximately 20 minutes, ensuring that the temperature stays constant as much as possible 5. Repeat for another trial in same temperature water 6. Repeat steps 1-5 using 10 C (ice bath) and 40 C (hot plate) water respectively

Data: Rate of Oxygen Consumption (kPa/sec) Adjusted Germinated and Non-Germinated Pea Rates of Oxygen Consumption (Average of 2 trials):

Data: Hot Temp (40°C) Cold Temp (10°C) Room temp (~20°C) red=germinated blue=non-germinated green=glass beads

Conclusion: - The germinating and non-germinating peas had the fastest rate of oxygen consumption at room temperature. - The next fastest rate was at 10 C. The colder temperature most likely slowed down the metabolic rate of the seed. - The slowest rate was at 40 C. After the corrected pressure difference, the slope for 40 C was positive for both trials of both germinated and non-germinated pea seeds -> possibly due to the denaturation of CR enzymes at/before 40 C - Gay-Lussac law (directly proportional relationship between pressure and temperature) - Hypothesis correct (germinated=faster CR than non-germinated for all 3 temperatures) * Error considerations: difficulty maintaining exact temperature in beaker, stopper/tubing too loose, experiment performed over course of three day period (varying temperatures). Where can we go from here? - At what temperature do the enzymes/proteins involved in pea respiration denature? - How are different species of plants affected by temperature? Is the point of denaturation of CR enzymes similar in most plants or does it vary by organism? - How is the metabolic rate of animals/small invertebrates affected by temperature?