AP Biology
Lab Report
Experiment
Title: The Effect of Salt Concentration on the Rate of Transpiration in Petunia Plants
Hypothesis: The greater the salt concentration, the faster the rate of transpiration. Rationale: High salt concentrations in the environment cause the plant cells to plasmolyse and lose water fairly quickly. Not only will the plant lose water through the stomata, but also through the root cells. The net change in mass would help determine how much water loss there was and in turn the rate of transpiration.
Purpose: The purpose of this study was to determine if there is a relationship between the salt concentration and transpiration rate. Animal cells require a certain salt concentration in the environment to remain stable and isotonic. Plants cells, however, have a cell wall and therefore would not need a salt concentration to keep their walls from lysing.
Methods:
1: A box containing six Petunia plants were store bought and separated into six cups.
2: Soil was added to each cup.
3: Six salt concentrations of approximately 100mL were prepared using appropriate masses of sodium chloride.
4: Each plant was assigned a solution randomly.
5: 10mL from each solution was added to the plant that the solution was assigned to using a pipette.
6: Once all the plants were watered, they were massed.
7: The watering and massing procedure was repeated for five days.
*The surface area of theleaves were also measured so that the transpiration rate could be calculated.
Dependent Variable: Transpiration Rate
Constants: Type of plant, watering, sunlight, nutrients,temperature, wind
Control: 0.0 M
