Transport in Plants Question 34
34. The most widely accepted theory for ascent of sap in trees is
[1991]
(a) capillarity
(b) role of atmospheric pressure
(c) pulsating action of living cell
(d) transpiration pull and cohesion theory of Dixon and Jolly
Show Answer
Answer : d
Hints & Solutions
(d) Transpiration pull and cohesion theory was put forward by Dixon and Jolly in 1894. According to this theory water rises due to the transpiration pull, continuity of water column and the cohesive power of water molecules from the lower part of the roots to the higher peaks of the trees.
