Question

what is mass flow hypothesis explain?

Answer 1



The theory behind Mass flow hypothesis which is also called as pressure flow hypothesis describes the movement of sap via phloem, proposed by the German physiologist Ernst Munch in 1930. A highly concentrated organic sugar especially sugar in the cells of phloem from a source like a leaf forms adiffusion gradient which draws water in the cells from adjacent xylem. This develops turgor pressure in the phloem which is also called as hydrostatic pressure.

Phloem movement occurs by mass flow from sources of sugar to sugar sinks. The phloem movement is bidirectional but unidirectional in xylem cells. Due to this multidirectional flow, it is not uncommon for sap in the sieve-tubes besides to move in opposite direction based on the fact that sap cannot travel easily between adjacent sieve tubes.