translocation of organic materials is best explained by\tinbibtion theory\tactive transport\tmass flow hypothesis

ThePressure Flow Hypothesis, also known as theMass Flow Hypothesis, is the best-supported theory to explain the movement of food through thephloem i.e. translocation.It was proposed byErnst Munch, aGermanplant physiologistin 1930.A high concentration of organic substance insidecellsof the phloem at a source, such as aleaf, creates a diffusion gradient(osmotic gradient) that draws water into the cells. Movement occurs by bulk flow (mass flow); phloem sap moves fromsugar sources tosugar sinksby means of turgorpressure, also known as hydrostatic pressure. A sugar source is any part of the plant that is producing or releasing sugar. During the plant's growth period, usually during the spring, storage organs such as therootsare sugar sources, and the plant's many growing areas are sugar sinks. The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward).