The diagram shows a beaker of water and molecules of red dye at the beginning of an experiment (Time 1) and the same beaker of water and molecules of red dye after 30 minutes (Time 2). Which of the following best explains what happened?

Question

a
Molecules of red dye moved by diffusion from a higher concentration to a lower concentration.
b
Molecules of water moved by active transport from a higher concentration to a lower concentration.
c
Molecules of water moved by osmosis from a lower concentration to a higher concentration.
d
Molecules of red dye moved by active transport from a higher concentration to a lower concentration.

Answer 1

The best explanation for what happened is:

a. Molecules of red dye moved by diffusion from a higher concentration to a lower concentration.

This option accurately describes the process by which the molecules of red dye spread throughout the water, moving from an area of higher concentration (where the dye is first added) to areas of lower concentration (the surrounding water), resulting in an even distribution over time.

The other options involve processes (active transport and osmosis) that do not apply to the movement of dye in this context.