Question

question 3
a scientist wants to test whether the ph, salinity, or temperature of seawater impacts coral development. he sets up an experiment with three conditions:
aquarium 1: normal ph, normal salinity, normal temperature
aquarium 2: high ph, high salinity, high temperature
aquarium 3: low ph, low salinity, low temperature
what factor would improve experimental design the most?
eliminating aquarium 1 since it only uses normal conditions.
testing one variable at a time and keeping the other two variables constant.
using one aquarium and changing the variables from day to day.
setting up the variables on a gradient in each aquarium.

Explanation:

In an experiment, to determine the effect of a variable, it is crucial to use the controlled - variable method. This means changing one variable at a time while keeping others constant. In the given experiment, multiple variables (pH, salinity, temperature) are changed simultaneously in Aquariums 2 and 3. By testing one variable at a time and keeping the other two variables constant, the scientist can accurately determine which variable (pH, salinity, or temperature) impacts coral development.

• Eliminating Aquarium 1 is incorrect because it serves as a control.
• Using one aquarium and changing variables day - to - day may introduce time - related confounding factors.
• Setting up variables on a gradient in each aquarium still does not isolate the effect of each variable as effectively as testing one variable at a time.

Answer:

Testing one variable at a time and keeping the other two variables constant.