Question

Pulsation theory was proposed by
A. Godlewski
B. Jagadish Chandra Bose
C. Dixon and Joly
D. Arthur

Answer 1

The theory believes that water from the outer side is absorbed by the innermost cortical cells of the root and drained into xylem channels.

Complete Answer:
- J.C.Bose(1923) put forward a popular theory of vital force regarding the ascent of sap . However, as water tends to rise upward in the plant in which roots have been cut or the living cells of the stem are destroyed by poison and heat, living cells do not tend to be involved in the ascent of sap.
- The living cells of the innermost layer of the cortex were experimentally shown to be in a state of pulsatory motion , i.e., alternate expansion and contraction. According to him, this pulsation triggered the pumping of water in an upward direction from cell to cell.
- This idea is, of course, an elaboration of Godlewski 's water translocalization. He experimented with an electric probe, a galvanometer, an electric dry cell, and a thin copper wire as a self-made apparatus.
- He took a potted plant connected to one point of the galvanometer, the other point of which was connected to a probe.The probe was slowly inserted into the stem. The galvanometer demonstrated momentary deflection for a longer time as it entered the innermost layer of the cortex.
- On either side of this particular sheet, no such deflection was observed. Bose inferred from this observation that the cells of this layer were in a state of pulsation. Upon extension, the cells absorbed water from the lower cells and contraction Water was pumped to the next higher cells. Bose has also found that for one Pulsation (i.e. contraction and expansion) it took 14 seconds to several minutes. The pulsation was named by J.C. Bose as the "heart-beating of plants."

The correct answer is option(B) Jagadish Chandra Bose.

Note: It has been calculated that to account for the usual rate of sap ascent, the sap must flow through 230 to 400 pulsatory cells per second. But it was already calculated by Bose that it took at least 14 seconds for a single pulse. Thus, the hypothesis did not provide a clear description of the mechanism of the growth of the sap and thus discarded.