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 nongerminated 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)
-.00004519
-.001664
-.001837
-.00009618
-.0002676
-.001356
.0004635
-.0002631
-.002294
-.0001346
-.001546
-.001020
.0002669
-.0004350
-.0009608
.0003844
-.0006285
-.001171
-.00050869
Adjusted Germinated and Non-Germinated Pea Rates of Oxygen Consumption (Average of 2 trials):
-.000513845
-.0011592 .000457
.000304
-.0014009
-.00033859
-.000519
-.00058185
-.0009175
.0005741
.000151
red=germinated
blue=non-germinated
green=glass beads
Cold Temp
(10°C)
Data:
Room temp
(~20°C)
Hot Temp
(40°C)
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?