Question

Cohesion transpiration pull theory of ascent of sap was proposed by
A) Munch
B) Stephen Hales
C) Dixon and Joly
D) Bose

Answer 1

Transpiration is outlined because the method during which loss of water happens within the kind of vapours from the aerial components of the plant. It happens chiefly through the stomata within the leaves. Transpiration has some properties similar to evaporation therein water from the wet surface is born-again into vapours type. Transpiration has some properties completely different from evaporation in being controlled by structural and physiological variations of plants.

Complete answer:
Transpiration is each necessary and evil too as a result of the loss of water is thus nice that it reduces water level within the soil and might cause the death of plant, however transpiration is often thought of as a necessary method for water and mineral absorption, ascent of sap and lowering the temperature (cooling effect).

Transpiration is evil because it causes loss of water. It is necessary as it causes movement of water from root to different components of plants. Despite the absence of a heart or vascular system in plants, the flow of water upward through the vascular tissue in plants can do fairly high rates up to fifteen metres per hour.

Now let us find solution from given options:
A) Munch : He gave mass flow hypothesis or can be termed as pressure flow hypothesis. He talked about translocation of food with the help of phloem.
B) Stephen Hales :He was known as father of plant physiology and provided a machine that is used for ventilating buildings.
C) Dixon and Joly : Most researchers believe that water is principally forced through the plant and therefore the propulsion for this method is transpiration from the leaves. This model that explains translocation of water by the method of transpiration, is thought as Cohesion tension- transpiration pull model (Dixon and Jolly) of water transport. But a simple fraction of water reaching the leaves is employed in chemical processes and plant growth. Most of it is lost through stomata within the leaves. This water loss is thought of as transpiration. Thus, water is transient in plants.
D) Bose : He gave contribution to plant physiology and told about response to stimuli. Our required option is c that is Dixon and Joly.

Hence the correct answer is option ‘C’.

Note: The transpiration driven ascent of vascular tissue sap depends chiefly on the subsequent 3 physical properties of water:
i) Cohesion : it's a sort of force Mutual attraction happens between water molecules.
ii) Adhesion : it a sort of force during which Attraction of water molecules happens to polar surfaces (such because the surface of tracheary parts like that of vascular tissue vessels)
iii) Physical phenomenon: The force during which Water molecules remain interested in one another within the liquid part as additional than to water within the gas part.