Question

what does it mean for an environment to be isotonic? (1 point)
○ the concentration of solute in the environment is different from the concentration inside the cell.
○ the concentration of solute is greater in the environment than inside the cell.
○ the concentration of solute is greater inside the cell than in the environment.
○ the concentration of solute in the environment and the concentration inside the cell are at equilibrium.

Explanation:

To determine the correct answer, we recall the definition of an isotonic environment. An isotonic solution (or environment, in the context of a cell) is one where the solute concentration outside the cell (in the environment) is equal to the solute concentration inside the cell. This state of equal solute concentrations is referred to as equilibrium in terms of solute concentration.

• The first option says the concentrations are different, which is incorrect for an isotonic environment (that would be hypertonic or hypotonic).
• The second option describes a hypertonic environment (higher solute outside the cell).
• The third option describes a hypotonic environment (higher solute inside the cell).
• The fourth option states that the solute concentrations in the environment and inside the cell are at equilibrium, which matches the definition of isotonic.

Answer:

D. The concentration of solute in the environment and the concentration inside the cell are at equilibrium.