Repeat the experiment adding only one drop of chloroplasts instead of 3. 5. If Spec 20s are in short supply, have half the class complete the chromatography section while the other half completes the photosynthesis section, and then have each group switch tasks. DPIP solution can be stored in a refrigerator for one month. Dispose of it by pouring it into a sink and flushing it down the drain with running water. Using the ideal gas law, students determine the respiration rates of germinating and nongerminating peas.
Students construct respirometers from pipets, cotton, weights, glass vials, and rubber stoppers.
Fill the trays with water the day before the lab. Soak the peas in water overnight, and then place them in moist paper towels inside a closed plastic bag for one day. Determine the respiration rates for other types of seeds and compare them. Place a sheet of paper under the respirometer pipets in the water bath to facilitate viewing the air bubble. Transformed cells grow on selective media, but nontransformed cells do not.