A single-celled photosynthetic protist, the euglena, is pictured here. A student has a sample of euglena in a culture. In order to determine the most likely aquatic environment where the euglena lives in nature, the student places samples of euglena in distilled water, 0.5% saltwater, and 5% saltwater. The student measures the activity of the contractile vacuole, an organelle to maintain homeostasis, at the various salinity levels. What are the variables and explain the expected results for this freshwater protist?
Responses
A Independent variable:number of contractions of the vacuole
Dependent variable:type of solution in which the euglena are placed
Expected result: Contractions will be highest in the pure water solution.
Independent variable:number of contractions of the vacuole Dependent variable:type of solution in which the euglena are placed Expected result: Contractions will be highest in the pure water solution.
B Independent variable:number of contractions of the vacuole
Dependent variable: volume of water in which the euglena was placed
Expected result: Contractions will be highest in the 5% saltwater solution.
Independent variable:number of contractions of the vacuole Dependent variable: volume of water in which the euglena was placed Expected result: Contractions will be highest in the 5% saltwater solution.
C Independent variable: type of solution in which the euglena are placed
Dependent variable: number of contractions of the vacuole
Expected result: Contractions will be highest in the pure water solution.
Independent variable: type of solution in which the euglena are placed Dependent variable: number of contractions of the vacuole Expected result: Contractions will be highest in the pure water solution.
D Independent variable: type of solution in which the euglena are placed
Dependent variable: number of contractions of the vacuole
Expected result: Contractions will be highest in the 5% saltwater solution.
Independent variable: type of solution in which the euglena are placed Dependent variable: number of contractions of the vacuole Expected result: Contractions will be highest in the 5% saltwater solution.
C Independent variable: type of solution in which the euglena are placed
Dependent variable: number of contractions of the vacuole
Expected result: Contractions will be highest in the pure water solution.