Question

The pulsation theory is related with

• A. Guttation.
• B. Bleeding.
• C. Vital theory for ascent of sap.
• D. Physical theory for ascent of sap.

Answer 1

The correct option is C Vital theory for ascent of sap.

Vital force theories:

The proponents of vital force theories believe that the ascent of sap is under the control of vital activities of the stem. Two theories are put under this category.

i. Rolay pump theory :

Godlewski (1884) proposed this theory. According him the rhythmic changes in the osmotic pressure of living cells of xylem parenchyme are responsible for upward movement of water.

This theory seemed only hypothetical and was discarded because ascent of sap continues in the stem in which the living cells are killed by poison.

ii. Pulsation theory :

According to sir J. C. Bose (1923) ascent of sap takes place due to pulsatory mechanism of living cortical cells present nearer to the vessels and tracheids of xylem. By means of electric probe needle he demonstrated the pulsatory mechanism of living cells.

This theory was also rejected because many workers could not repeat the experiment and there was no co relation between pulsatory activity and the ascent of sap.

Therefore, the correct answer is option C.