Lab 6 Flashcards
What does a respirometer calculate
Rate of oxygen consumption or cellular respiration
What type of seed is used
Pea seeds
Seed germination
Whether a seed has broken dormancy
What is reviewed and applied for this lab
Ideal gas law
What are individual cells responsible for
Energy exchanges necessary to sustain ordered structure
How do cells do necessary energy exchanges
Breaking down nutrient molecules to generate ATP
What does cell respiration require
Nutrient molecules and oxygen
What is cell respiration
Breaking down nutrient molecules to generate ATP to fuel cell processes
What are products of cell respiration
Carbon dioxide and water
Equation for cell respiration
C6H12O6 + 6O2 –> 6CO2 + 6H2O
Ways to measure rate of cell respiration
Monitoring changes in temperature
Measure oxygen consumption or carbon dioxide production
Why can temperature be used
Respiration is Exergonic and produces heat
What is a respirometer
Devices that measure gas volume changes
What is needed to use a respirometer
Ideal gas law
Ideal gas law
Describes relationship between temperature, pressure, and volume
PV=nrT
What gases are changing in volume during cell respiration
Oxygen and carbon dioxide
What is happening to oxygen
Consumed by respiring cells
What is happening to carbon dioxide
Diffusing out
How can the respirometer deal with two gases
Potassium hydroxide which absorbs carbon dioxide
KOH formula
CO2 + 2KOH –> K2CO3 + H2O
What is potassium carbonate
A solid precipitate
What happens to carbon dioxide when potassium hydroxide is added
Turns into a solid, so respirometer will only measure consumption of of oxygen
What respirometers will be used and how
2 sets of 3, submerged in water
Each set at a different temperature
One with germinated seeds, one with non-germinating seeds and plastic beads, and one with beads
Also contain cotton saturated with KOH
Why the beads
To ensure each respirometer is uniform in volume
Why cotton
Carbon dioxide will be absorbed
What will happen in pan of water
Water will flow from high pressure to low pressure
Oxygen used up by seeds, gas pressure inside respirometer will decrease, water will flow into the pipette down pressure gradient
What do pictures look like
Pipet tip Seeds on top Beads Dry cotton Absorbent cotton with KOH Weights underneath
How many of each type of seed
50
How will the beads be
In a container
Ho many stoppers
6
What will be attached to stoppers
1 mL graduated pipettes
How many paper towels
6
How many water bath containers
2
What type of graduated cylinder
100 mL
How many thermometers
2
What other materials
Absorbent cotton No absorbent cotton Sharpie Ice Masking tape Cell phone timer Bucket of water Scissors Plastic trash bucket
What will be in the dropper bottle
15% KOH
What about respirometer tops
Be careful
They’re rubber with pipette sticking out
Will lose seal
Step 1
Label paper towels 1a, 2a, 3a, 1b, 2b, 3b
What is step 2
Label respirometer a with sharpie, same as paper towels
Step three
Fill grad cylinder with 50 mL of water
Put 25 germinating seeds in the cylinder
Record volume in Data Table 1a
Subtract 50 mL to determine total volume of seeds and record same place
Pour out water into trash bucket and put seeds on paper towel 1a
What is step 4-5
Same as step 3, but after you do 25 dry seeds, count in plastic beads until volume matches
Record same place
Put mixture on 2a
Step 6
Same as last ones, but add beads till get same volume
Data table 1a
Beads on paper towel 3a
What is step 7
Do it for the b respirometer said and record in 1b
What are the lines at in the pipette
Hundredths
Step after weighing
Put absorbent cotton to bottom of weighted vials, push down with wooden stick or stirring rod
Saturate with 4 drops of 15% KOH
About KOH
Caustic
After absorbent cotton
No absorbent cotton, push to bottom
Why non absorbent
Peas don’t touch poisonous KOH
After cotton
Add peas and beads
Put in stoppers
Should be tight and not wiggle much
Where does part 2 start
After filling vials
Part 2 step 1
Will baths with tap water 1 inch from top
Room temp, and cold temp by adding ice til 10 degrees Celsius and 25 Celsius
Continue adding ice, ask Mallett
Second step part 2
Masking tape across narrow width of bath, 2/3 way from 1 end
Wither notebook paper in bottom of tub to read pipettes easier
Step three part 2
Place thermometers on floors of baths, take temps record 1C
Step 4 part 2
Put a respirometers in room temp water bath so pipette rest on masking tape
Same with b, but put them in cold
What to do after placing respirometeso
Time for 7 minutes - equilibration period to be same temp as water
Don’t hit bath or table at any point
Start time then
Mrs. Mallet show you how to put in food coloring
Where will lab need to be fast
After food coloring
Fast part
At end of 7 minutes, put tubes entirely in baths
Cut tape ends so respirometers go in gently
Some water gets in pipettes, but influx should stop quickly, if it continues check for leaks and call for Mallett
Second step fast
Make sure you can read scale
Air bubble should extend from main chamber up tube of pipette
Record water level onto the data table at time interval 0
Record position of water in each pipette 5, 10, 15, 20 min data table 2
Clean up
Due respirometers onto paper towel and rinse beads put them back in container from Mallett so they dry
Throw out peas
Scissors to pull out cotton and throw away
Slide water tubs toward sink and dump water - careful
Sham wow dry water from pans
Rinse pipettes with distilled water
Once water is clear,s hake pipette over sham wow to remove as much water as possible and return pipette where instructed, don’t break it or its seal
Two questions
How temp and seed germination affect rate of respiration
