Q37 - Root Water Movement and Osmotic Regulation
Figure 1 provides a schematic representation of one eudicot plant’s growing root. It illustrates, through red arrows, the pathway of water solution movement within a healthy plant under optimal conditions.
Assume that the water solution inside the cells of the B zone has an osmolarity of 0.3 osmoles per liter (Osm/L).
Figure 1. Diagram of a plant root; Zone A - soil, Zones B and C - parts of the root.
On your answer sheet, indicate “T” for true statements and “F” for false ones.
A. All molecules of water cross through the plasma membrane to enter zone B from zone A.
B. In a healthy plant and under natural conditions, the concentration of free water molecules in zone B is greater than in zone A.
C. During a flood, certain plants experience cellular death in zone B. This process results in the formation of voids.
D. If we clean the roots of this plant and place them in a 0.2 molar NaCl solution, the cells in zone B will begin to lose water.
Question reproduced from IBO 2024, Theoretical Exam Part A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)