Question

Match the theories given in column I with the names of scientists listed in column II. Choose the answer which gives the correct combination of the alphabets.

• A. A = r; B = s; C = t; D = q
• B. A = s; B = r; c = p; d = q
• C. A = r; B = q; C = t; D = p
• D. A = q; B = p; C = t; D = r

Answer 1

The Correct Option is A

The theories given in question are related with ascent of sap (the process of translocation of sap from the roots to the top of the plants). Relay pump theory was given by Godlewski in 1884. According to this theory living tissues in the xylem bring about the pumping action of water in an upward direction. Transpiration-Cohesion theory, given by Dixon and Jolly in 1894, is based on following three facts: -Cohesive force or tensile strength of water -Continuity of water column -Transpiration pull Mass flow theory was given by Ernst Munch (1927, 1930), according to which food material is translocated through phloem along the concentration gradient between the source of food material to the site of utilization i . e ., sink. Pulsation theory was given by J.C. Bose in 19

Answer 2

Ans. Relay pump hypothesis (also known as the Cammbering theory): According to Godlewski (1884), the ascent of sap is caused by a rhythmic shift in the osmotic pressure of live cells in the xylem parenchyma and medullary rays, which causes water to pump upward. The notion was backed by Janse (1887), who demonstrated how the top leaves were impacted if the bottom half of the shoot was destroyed.

Henry Dixon, a botanist, first suggested the idea of water pulling itself upward in 1939, according to the transpiration cohesion hypothesis. Water is pulled from roots to leaves by tension created when a plant's leaves transpire water. Due to the cohesiveness that water molecules exhibit towards one another, this tension needs to be maintained. The water column doesn't break because of this cohesive force between the water molecules. Water cannot divide because of hydrogen bonding, therefore it is drawn upward through the continuous fluid column. 

The pace at which a huge fluid moves through a unit area is known as mass flow rate. The density, velocity, and size of the cross-section all influence mass flow. It is the movement of mass per unit of time, in other words. Its units are kilograms per second. The mass flow rate formula is as follows:

Mass Flow Rate = (density)*(velocity)*(area of the cross-section)

m = ρ v A

Where,