Question

Which of the following statements is/are true?
A. The apoplastic movement of water occurs exclusively through the cell wall without crossing any membranes.
B. Solutes present in a cell (or in any solution) increase the free energy of water or water potential.
C. The symplastic movement occurs from cell to cell through the plasmodesmata.
D. Membrane permeability depends on the membrane composition, as well as the chemical nature of the solute.

• A. A and B only
• B. B and D only
• C. A, C and D only
• D. A, B and D only
• E. C only

Answer 1

Answer: (C)

A, C and D only

The apoplast pathway comprises of non living components of a plant body i.e., intercellular spaces and cell wall. The movement through apoplast is unregulated and fast. Symplast comprises of living components i.e., protoplasm, cell membrane and plasmodesmata. Water potential or free energy of water depends on the number of water molecules in the system. More the number of water molecules greater will be water potential. When solutes are dissolved in water, there is a decrease in relative number of water molecules and this causes corresponding decrease in water potential. Membrane permeability depends on the nature of biological membrane and the nature of solutes. The membrane is composed of phospholipids and proteins. Consequently lipophilic substances can freely pass through the membrane, while hydrophilic substances cannot freely pass through the membrane and require special carrier or transport proteins for transport across the membrane.