Cellular Respiration Lab
Purpose
To examine variables affecting rate of cellular respiration
We will be measuring disappearance
of oxygen (oxygen consumption) to
measure reaction rate.
Setup: Respirometers
Respirometers
CO2 + 2KOH → K2CO3 + H2O
Oxygen is consumed through cellular respiration. Since the carbon
dioxide that is produced reacts with KOH, water will enter the pipet in
correlation with the consumption of oxygen.
Trays
You will have room to run THREE respirometers at one time in a water bath.
Set up each
respirometer with
its tip out (on a
tape sling).
Submerge all
respirometers at
the same time to
begin your
experiment.
Data Collection
Record data every 5 minutes over a time period of 20
minutes
White paper and a
drop of food coloring
at the tip of your
pipet can help you
easily visualize
where the water
level is inside of your
pipet.
Negative Control
You must run a negative control (beads) in each experiment,
to generate the correction factor
Difference vs. Corrected Difference
Difference:
Reading - Initial reading (at t = 0)
CORRECTED Difference:
Experimental difference - negative control difference
If there is any movement in your negative control (bead) respirometer, it
must be due to some other factor besides cellular respiration and must be
subtracted out of all of your data (for any other respirometer in the same
water bath).
Variables
Your lab group should pick the type of organism (independent
variable) to examine in this lab (you only have 3
respirometers):
Choose TWO different types to do a direct comparison
Available Organisms
DRY PEAS
GERMINATING
PEAS
CRICKETS
EARTHWORMS
Bring in your own organisms!
YOU MUST GET TEACHER APPROVAL BEFORE YOU BRING IN YOUR OWN ORGANISMS!
TERRESTRIAL ISOPODS
BEETLE LARVAE (IN ACORNS)
BEFORE Lab
Plan out protocol and get teacher approval
Put PRELAB into your lab notebook:
A.Title
B.Introduction/background (cellular respiration, respirometers, organisms)
C.Hypothesis
D.Experimental design/methodology
Prelab will be checked for a homework grade on lab day!
DURING Lab
Each group will receive a lab EXIT TICKET.
The exit ticket has 10 questions about the lab.
The questions must be completed by the end of lab, and the exit ticket must be
turned in to your teacher before you leave lab.
Each lab group member must be responsible for at least 2 questions! (You will
initial next to each question to note who is responsible for which question.)
AFTER Lab
Your lab grade will be your team exit ticket.
Complete your lab in your notebook before the quarter 1 notebook check:
E. Data (tables containing raw data, any additional observations)
F. Analysis (corrected data calculations, 2 graphs: course of reaction and rate)
G. Conclusion (no additional questions, since they’re on the exit ticket)
Rejecting/not rejecting hypothesis,
Answers to any lab questions,
Connection to course material
Suggested modifications to methodology or additional testing