Question

J.C. Bose proposed this theory to explain the process of ascent of sap

• A. Relay-pump theory
• B. Transpiration pull theory
• C. Pulsatory theory
• D. Capillary force theory

Answer 1

Answer: (C)

Pulsatory theory

"Vital force theory" is a proposed mechanism for the ascent of sap through the xylem tissue of plants. According to the vital force theory, the conduction of water up the xylem vessel is a result of vital action of the living cells in the xylem tissue. These living cells are involved in ascent of sap. Relay pump theory and Pulsation theory support the active theory of ascent of sap. Jagadish Chandra Bose suggested a mechanism for the ascent of sap in 1927. His theory can be explained with the help of galvanometer of electric probes. He found electrical ‘pulsations’ or oscillations in electric potentials, and came to believe these were coupled with rhythmic movements in the telegraph plant Codariocalyx motorius (then Desmodium). On the basis of this Bose theorized that regular wave-like ‘pulsations’ in cell electric potential and turgor pressure were an endogenous form of cell signaling. According to him the living cells in the inner lining of the xylem tissue pump water by contractive and expulsive movements similar to the animal heart circulating blood.

So the correct option is 'pulsatory theory'.