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