Use the diagram below to answer the question.
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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?
a
Molecules of red dye moved by diffusion from a higher concentration to a lower concentration.
b
Molecules of red dye moved by active transport from a higher concentration to a lower concentration.
c
Molecules of water moved by active transport from a higher concentration to a lower concentration.
d
Molecules of water moved by osmosis from a lower concentration to a higher concentration.
The correct answer is a) Molecules of red dye moved by diffusion from a higher concentration to a lower concentration.
Based on the diagram, the best explanation for what happened is option a: molecules of red dye moved by diffusion from a higher concentration to a lower concentration. This is indicated by the fact that initially at Time 1, there is a higher concentration of red dye molecules on the left side of the beaker compared to the right side. However, after 30 minutes at Time 2, the concentration of red dye molecules became more evenly distributed throughout the beaker, indicating movement from a higher concentration to a lower concentration through diffusion.
To answer this question, we need to understand the process that is happening in the beaker. From the provided diagram, we can observe the movement of molecules in the beaker before and after 30 minutes.
Looking at the diagram, we see molecules of red dye that are initially concentrated in one area of the beaker (Time 1). After 30 minutes (Time 2), the red dye molecules seem to have spread out more evenly throughout the beaker.
Based on this information, the most likely explanation is option (a): Molecules of red dye moved by diffusion from a higher concentration to a lower concentration.
Diffusion is the passive movement of particles from an area of higher concentration to an area of lower concentration. In this case, the red dye particles are initially more concentrated in one area (Time 1) and then spread out more evenly throughout the beaker (Time 2). This movement of the red dye molecules is a classic example of diffusion.
Option (b), active transport, is not applicable here because it involves the movement of molecules against their concentration gradient, requiring energy. Since the red dye molecules are moving from higher to lower concentration, it is a passive process and does not require energy.
Option (c), molecules of water moving by active transport, is also not applicable because the question specifically refers to the movement of red dye molecules and not water molecules.
Option (d), molecules of water moving by osmosis from lower concentration to higher concentration, is incorrect because osmosis refers to the movement of water molecules across a semipermeable membrane, typically from an area of lower solute concentration to an area of higher solute concentration. The diagram and the question do not mention the presence of a semipermeable membrane that would allow osmosis to occur.
Therefore, the best explanation based on the information provided is (a) "Molecules of red dye moved by diffusion from a higher concentration to a lower concentration."