Question

The vital force theory was rejected because

• A. It was unable to correlate pulsatory action of living cell and upward movement of sap.
• B. A remarkable difference is observed between the rate of pulsation and rate of ascent of sap.
• C. Both A and B.
• D. None of the above.

Answer 1

The correct option is C Both A and B.

The classical vital theories attempted to explain mechanism of ascent of sap. The vital force theory was a theory presented by Berzelius. The theory stated that for the ascent of sap vital capacity of a living cell is necessary. Many scientists supported the theory by demonstrating their experiments. Some of such theories are Godlewski's relay pump theory and Bose's pulsatory movement theory. These classical theories have not been accepted much and rejected by the German scientist Wohler because of some reasons. For example, according to these theories ( Godlewski's relay pump theory), the force necessary for the ascent of sap is provided by the living cells of plants. He also assumed that a pumping action was generated due to the rythmic change in the water potential of the living cell to raise water upward against gravity. Further, it was found by Strasberger that translocation of water was continued even after the death of living cells. Many scientists like Dixon, Shull, MacDougal etc. proposed that pulsatory movement and the rate of water translocation is not related to each other. The normal rate of ascent of sap at which sap flows through pulsatory cells was observed 230 to 400 pulsatory cells per second. Whereas, earlier it was observed (by Bose) 14 seconds, for one pulsation. The remarkable difference was observed between them and the theory was rejected. Therefore, the correct option is C.