Cell Respiration Lab
rank seeds from fastest to slowest rates of respiration
1) Room temp germinated 2) 10C germinated 3) 10 C dry 4) Room dry
3 ways cellular respiration can be measured
1) consumption of O2 (in this lab) 2) production of CO2 3) release of energy
3 purposes of lab
1) measure oxygen consumption during germination 2) measure change in gas volume in respirometers containing either germinating or nongerminating seeds 3) measure rate of respiration of peas at 10 C or room temp
Explain relationship between amount of O2 consumed and time
As time increases, O2 consumption increases
Explain how the water moving in shows that oxygen is being consumed
CO2 converting to solid causes O2 volume to be reduced Net decrease in gas volume --> decrease in pressure Water moves into pipette Water displacement shows mL of O2 consumed
Explain the roles of the cotton
First put in KOH-soaked absorbent cotton Then put nonabsorbent cotton over it
Hypotheses for lab
Germinating seeds will have higher respiration rate Seeds in warm temperature will have higher respiration rate (both were correct)
mL O2 consumed vs Temp graph
Graph goes up constantly but then around 45C it spikes down bc denaturing of enzyme
What compound removes CO2 to form solid K2CO3?
KOH; CO2 + 2KOH = K2CO3 + H2O
If respiration in small mammal were studied at both room temp and 10C, what results would you predict?
Lower respiration rate at 21C Faster respiration rate at 10C because its colder so mammal needs to respire faster to create more heat
Using same experiment, compare respiration rates of 25 g reptile and 25g mammal at 10C
Mammals are endotherms- need respiration to maintain warmth Reptiles are ectotherms- coldblooded Mammals will have higher rate
Gas Law
PV=nRT
Why do you need to stopper?
Prevent gases from leaving
What does slope of graph tell you?
Rate in mL O2/minute
Why do you lean tubes against tape first then immerse them in water?
So they can adjust to the temperature
Graph of data
Time- x-axis mL of O2 consumed- y-axis Straight lines
Constants in experiment
amount of KOH cotton # seeds temperature (for each set of 3)
Why do you correct readings from peas with the readings from the beads?
beads are only acting as something to take up space to make volumes equal needs to be subtracted at end to compare germinating vs dry peas
purpose of glass beads
detect change in atm pressure acts as control- make sure pressure stays constant
Explain effect of germination vs non on pea seed respiration
germinating seeds have higher respiration rate bc they are alive they require more energy
Gases and liquids flow from regions of _____ pressure to regions of ____ pressure.
high to low
Where does the water in the pipette come from?
made from the reaction goes up the pipette bc O2 is being consumed so theres less pressure in pipette
Why did you put beads with dry peas?
make all the volumes equal then subtracted volume of beads later
The more water that goes in the pipette, the less _______ in pipette, which means more ____ was consumed
pressure; O2
Purpose of KOH
prevent CO2 from interfering with gas pressure
What was measured in the lab?
relative volume of O2 consumed
Aerobic cellular respiration
release of energy from organic compounds by metabolic chemical oxidation in mitochondria within each cell; oxygen is required
How does CO2 being removed relate to the experiment?
since its being removed, O2 volume is decreasing
How do u calculate mL of oxygen consumed?
subtract volume of water from total volume of pipette
what if you examined rates of cellular respiration with peas that have been germinating for 0, 24, 48 and 72 hours. Results?
time increases, rates increase. but if it's fully grown, then the rates would fluctuate
What 2 things had to remain constant in order for lab to work?
water temp and volume
