What does the pressure-flow hypothesis explain?

The Pressure-Flow Hypothesis It proposes that water containing food molecules flows under pressure through the phloem. The pressure is created by the difference in water concentration of the solution in the phloem and the relatively pure water in the nearby xylem ducts.

What is pressure-flow hypothesis Class 11?

The Pressure Flow Hypothesis is also known as the Mass Flow Hypothesis. It is the most accepted theory of movement of food through phloem. it was proposed by Ernst Munch in 1930s. A high concentration of glucose in the cells of phloem at the source sets up osmotic gradient.

How does the pressure-flow hypothesis explain the function of phloem?

Explanation. The pressure-flow hypothesis explains how the sugar molecules from a source cell forms a high concentration inside the cells of the phloem. This causes an osmosis that draws the water from the xylem to go into the cells of the phloem.

What fluid moves through pressure-flow hypothesis?

The accepted mechanism needed for the translocation of sugars from source to sink is called the pressure flow hypothesis. According to the “Pressure-Flow Hypothesis”, water and dissolved sugars flow through the sieve tubes from an area of higher pressure to an area of lower pressure.

Who gave the mechanism of pressure-flow hypothesis?

In angiosperms, increasing evidence shows the pressure-flow hypothesis, formulated by Ernst Münch in 1930 [1••], to adequately explain the mechanism of phloem transport [2].

What is the function of P protein?

The main function of the phloem is conduction of food materials. P-protein and callose protein act as damage control team. P-protein is also called as phloem protein. If there is disruption of sieve element, P-protein aggregates at the sieve plate and prevents the leakage of phloem exudates.

Who proposed the pressure flow hypothesis?

Ernst Münch
43 Physiology and metabolism 2018 In angiosperms, increasing evidence shows the pressure-flow hypothesis, formulated by Ernst Münch in 1930 [1••], to adequately explain the mechanism of phloem transport [2].

What is mass flow hypothesis Class 10?

Mass flow hypothesis is the theory that translocation of sugars in the phloem is brought about by a continuous flow of water and dissolved sugars between sources and sinks. (A source is the site of production of sugars, usually leaves, and the sink is the site of their utilization, for example the root system.)

How does the pressure flow theory explain the movement of sugar through the plant?

Pressure Flow At the sources (usually the leaves), sugar molecules are moved into the sieve elements (phloem cells) through active transport. Water follows the sugar molecules into the sieve elements through osmosis (since water passively diffuses into regions of higher solute concentration).

What causes sap to flow out of the tube?

Tree sap flows through sapwood, which produces carbon dioxide. Sometimes this carbon dioxide causes pressure to build up within the tree. If there are any wounds or openings, this pressure will eventually force the tree sap to ooze from the tree.

Where is P-protein found?

P-proteins or phloem proteins are proteinaceous substances found in cells of flowering plant phloem, particularly in seive tube members where it may block or hinder translocation through sieve pores.

Where are P-proteins synthesized?

P-proteins subunits are synthesized in immature, nucleated sieve elements (Cronshaw and Esau, 1967,1968; Esau and Cronshaw, 1967; Noll et al., 2007,2009; Rüping et al., 2010; Bucsenez et al., 2012; Ernst et al., 2012) and initially assemble as large protein bodies (Steer and Newcomb, 1969).