cell respiration (lab)

if you used the same experimental design to compare the rates of respiration of a 25 g mammal at 10°C, what results would you expect? explain your reasoning.

I would expect the respiration to be higher in the mammal, since they are warm-blooded; they respire more to keep their higher body temperature at 10°C. in other words, mammals produce more ATP to keep warm, unlike reptiles, who are cold-blooded and survive in lower temperatures.

what might happen to the oxygen consumption of the peas if the temperature continues to increase up to 45°C?

as the temperature increases, the enzymes will start to denature, therefore inhibiting germination

explain the effect of germination (versus non-germination) on pea seed respiration.

in germination, the seeds are growing and need to respirate in order to continue growing. the germinated peas will therefore consume more oxygen than those not germinated

what would the dependent variable be in the experiment?

oxygen consumption (mL)

if respiration in a small mammal were studied at both room temperature (21°C) and 10°C, what results would you predict? explain your reasoning.

respiration would be higher at 10°C because the animal would have to keep up its body temperature and remain in a state of homeostasis; the small mammal would essentially be producing more ATP in order to keep its body temperature up. not much respiration would be needed at 25°C because it is already warmer and there isn't as much of a temperature regulation needed.

design an experiment to examine the rates of cellular respiration with peas that have been germinated for different lengths of time: 0, 24, 48, and 72 hours. what results would you expect? why?

set up four respirometers as the following: (1) seeds that have not begun to germinate, (2) seeds that have been germinating for one day, (3) seeds that have been germinating for two days, (4) seeds that have been germinating for three days. it is expected that there will be no oxygen used by the seeds that have not germinated yet; the seeds that have germinated for three days would consume most of the oxygen and as the time passes, the rate of cellular respiration increases.

what is the relationship between the amount of oxygen consumed and time?

the amount of oxygen consumed was greatest in germinating peas in warm water; as time increases, the consumption of oxygen increases too

why did the vial have to be completely sealed around the stopper?

the stopper at the top of the vial needs to be completely sealed so that no gas can leak out of the vial or water to enter into the vial

what would the independent variable be in the experiment?

time (minutes)

what is the purpose of KOH in this experiment?

to react with/absorb the carbon dioxide and form an insoluble precipitate (solid), so that it doesn't affect the gas pressure of oxygen entering the respirometer when the carbon dioxide is trying to be released

why is it necessary to correct the readings from the peas with the reading from the beads?

to show the actual rate at which cellular respiration occurs in the peas; the beads were the control variable. changes in the environment (e.g. in atmospheric pressure and temperature) affect the rate of respiration, so the readings are corrected to prevent the results from being inaccurate.

explain why water moved into the respirometers' pipettes.

while the peas underwent cellular respiration, they consumed oxygen and released carbon dioxide. the carbon dioxide reacted with the potassium hydroxide resulting in a decrease in the volume of gas in the pipette and the vial. because the pipette tip was exposed to the water bath and there was a lower pressure, water moved into the pipette.

identify two hypotheses being tested in this lab.

• if germinated peas and non-germinated peas are used, then the germinated peas will consume more oxygen or respirate more. • if the temperature of the water bath is cooler, then the rate of respiration will be slower.

what are some controls/constants, and why do you need them?

• the water baths are held at a constant temperature • the volume of KOH is equal in every tube • the equilibration time is identical for all respirometers *constants and consistency are needed to keep the data accurate and reliable