IB Biology, Revised 2014-15 / IHS
D-I-Y Lab: “The Seedy Side of
Respiration”
Adapted from Lab 5, “Cell Respiration,” AP Biology, © 2001
Overview
In this experiment, we will investigate the
metabolism of germinating seeds. A germinating seed consists of
a live, respiring plant embryo (which does not have functional
leaves and is therefore not yet performing appreciable
photosynthesis) and a food supply, all surrounded by a
protective seed coat. In this design-it-yourself lab, you have
the opportunity to design a controlled experiment to test the
effect of an environmental factor on cellular respiration.
Before doing this lab, you should understand
Respiration, dormancy, and germination (see Neil 9e pp 808-809)
How respirometers and CO2 gas sensors work (you have your choice of
assays)
The general processes of metabolism in cells, and
How the rate of cellular respiration relates to the amount of activity
in the cell.
After doing this lab, you should be able to:
Calculate the rate of cellular respiration from experimental data
Relate specific gas production or consumption to respiration rate
The fine print
1. You will need to prepare your own seeds. To use peas, soak them in tap
water about 6 h (or overnight) and then place them between layers of
moist paper towel for 24 h before using them.
2. CO2 sensors cannot be placed directly into liquid! They only measure
CO2 in air.
Some available materials (you used many of these in the basic
assays):
15% KOH
250-mL gas sampling bottles
Absorbent and nonabsorbent cotton
Blenders
Centrifuges
CO2 gas sensor probes
Glass beads/rocks
Goggles and aprons
Graduated cylinders and other
glassware
Hot plates
Ice
LabQuest data logging devices
Large pans and newspaper
Peas (Alaska variety, possibly
others)
Respirometers (vials &
stopper/pipette assemblies)
Water baths