Question

In your experiment, you tested the hypothesis: If molecules are small enough, then they will diffuse across a semipermeable membrane because they can pass through its tiny openings. The independent variable in this experiment was ____, and the dependent variable was _____.

a) Temperature; diffusion rate
b) Molecule size; diffusion
c) Time; membrane thickness
d) Concentration; membrane color

Answer 1

The hypothesis being tested is that diffusion across a semipermeable membrane is dependent on molecule size. Therefore, the independent variable is molecule size, and the dependent variable is diffusion.

Step-by-step explanation:

In the stated experiment, the hypothesis being tested is that small molecules will diffuse across a semipermeable membrane due to their ability to pass through its tiny openings. Here, the independent variable is the molecule size, as it is what is being changed to test the effect on diffusion. The dependent variable is the diffusion itself, as it is what is being measured or observed when the molecule size is varied.

Looking at the options given:

• Temperature would be considered an independent variable if we were testing its effect on diffusion rate, not the molecule size.
• Time and membrane thickness might be relevant in other contexts but are not directly related to the hypothesis being tested in this experiment.
• Concentration affecting membrane color is not relevant to this hypothesis which concerns molecule size and diffusion.

Therefore, the correct answer is molecule size as the independent variable, and diffusion as the dependent variable.