Designed to demonstrate cellular respiration, this experiment shows that germinating pea plants consume more oxygen than nongerminating plants and that peas germinating in warm water consume more oxygen than those in cold water.
- Measure displacement of water
Set up two water baths, one at 25 degrees and one at 10 degrees Celsius. Fill a 100 mL cylinder with 50 mL of water, drop in 25 germinating peas and record the volume of displaced water. Place the peas on a paper towel for use in Respirometer #1. Refill the cylinder with 50 mL of water, and drop in 25 nongerminating peas. Add glass beads until the volume is equal to that of the germinating peas. Remove the beads and peas for use in Respirometer #2. Refill the cylinder with 50 mL of water, and add glass beads to equal the volume of the germinating peas. Remove the beads for use in Respirometer #3. Perform the same steps for Respirometers #4, 5 and 6.
- Insert materials into vials
In each of six vials, place a wad of cotton saturated with 15-percent potassium hydroxide and a wad of dry cotton. Place the first set of germinating peas, dry peas plus beads and beads alone in Vials 1, 2 and 3, respectively. Place the second set of germinating peas, dry peas plus beads and beads alone in Vials 4, 5 and 6. Insert Vials 1, 2 and 3 into the 25-degree water and Vials 4, 5 and 6 into the 10-degree bath with pipettes.
- Record the results
Completely immerse the six respirometers in water for ten minutes. Then record the volume of water in each pipette every five minutes for twenty minutes. Water will move toward the areas of decreased pressure created by higher consumption of oxygen due to cellular respiration.