WebThe Mass-flow Theory of Phloem Transport; A Supporting Calculation L. K. WIERSUM Institute for Soil Fertility, Groningen Received 14 July 1966 The mechanism of long … Webof solutes through the phloem. Munch’s Mass Flow Hypothesis The mass flow or pressure theory was first proposed by Munch (1930) and later elaborated by Crafts (1938). According to this theory, organic solutes are translocated en masse through the sieve tubes from the source (leaves) to the storage sites (roots, fruits and tubers).
Pressure (hydrostatic) flow gradient
The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward). Because of this multi-directional flow, coupled with the fact that sap cannot move with ease between adjacent sieve-tubes, it is not unusual for sap in adjacent sieve-tubes to be flowing in opposite directions. Ver más The pressure flow hypothesis, also known as the mass flow hypothesis, is the best-supported theory to explain the movement of sap through the phloem. It was proposed by Ernst Münch, a German plant physiologist in … Ver más There are different pieces of evidences that support the hypothesis. Firstly, there is an exudation of solution from the phloem when the stem is cut or punctured by the Stylet of an aphid, a classical experiment demonstrating the translocation … Ver más Some plants appear not to load phloem by active transport. In these cases a mechanism known as the polymer trap mechanism was … Ver más 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 the Ver más While movement of water and minerals through the xylem is driven by negative pressures (tension) most of the time, movement through the phloem is driven by positive hydrostatic … Ver más Opposition or criticisms against the hypothesis are often voiced. Some argue that mass flow is a passive process while sieve tube vessels … Ver más Web25 de ene. de 2024 · Mechanism of Translocation In The Phloem The process of translocation of sugars from source to sink in plants is best explained by the mass flow hypothesis or pressure flow hypothesis, given by German physiologist Ernst Munch in 1930 and elaborated by Grafts. According to this hypothesis- 1. semara beach house
14.6 Pressure Flow Theory Mechanism of Phloem Transport
WebLong-distance transport in the phloem takes place in living cells, the sieve tubes (Fig. 3.9).The principles of the phloem transport mechanism were proposed as early as 1930 by Münch in a pressure flow hypothesis based on the principle of an osmometer (Chapter 5; White, 2024).Münch suggested that solutes such as sucrose are concentrated in the … WebMost accepted theory on Phloem translocation Mass flow of solute is a passive process occurs from source to sink along a hydrostatic pressure gradient or Turgor pressure gradient HPG exists between source and sink This difference drives the movement of solutes from leaves to other parts through phloem Web8 de oct. de 2013 · As phloem of higher plants has multiple functions in plant development, reproduction, signalling, and growth, the fundamental understanding of the mechanisms … semarang city size