Question 1
Multiple choiceEasy1 markThe figure compares equal-volume samples; each dot represents the same dissolved solute. Which statements are correct?
I. A plant cell in medium P gains water and develops turgor pressure.
II. In medium Q, the plasma membrane pulls away from the cell wall because water enters the plant cell.
III. IV solution R is isotonic to blood-cell contents and is suitable because it causes no net water movement across cell membranes.
Which statements are correct?
Show answer and explanation
Answer: B. The equal-volume samples show that P has a lower solute concentration than the plant-cell contents, so water enters and turgor pressure develops. Q has a higher solute concentration, so water leaves and the plasma membrane pulls away from the cell wall (plasmolysis). R has the same solute concentration as the blood-cell contents, so it is isotonic and causes no net water movement.
A: omits III; equal concentrations in R indicate an isotonic solution suitable for intravenous use.
C: omits I; the lower solute concentration in P causes water to enter the plant cell.
D: reverses water movement in Q; water leaves the cell, rather than entering it.
Remember: hypotonic media cause water entry; hypertonic media cause plasmolysis.