sugar concentration theory ..!how turgor pressure is develop!
Answers
Explanation:
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 1930. A high concentration of organic substances, particularly sugar, inside cells of the phloem at a source, such as a leaf, creates a diffusion gradient (osmotic gradient) that draws water into the cells from the adjacent xylem. This creates turgor pressure, also known as hydrostatic pressure, in the phloem. Movement of phloem sap occurs by bulk flow (mass flow) from sugar sources to sugar sinks. 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
✡The phloem cells at source have a high concentration of sugar that draws water into them, creating a gradient in turgor pressure, which is higher in the source and lower in the sink. Movement of the phloem sap occurs by bulk (mass) flow down the turgor gradient to the sink.
✿Sugar concentration theory is very old theory according to which in the daytime, guard cells of the plant leaf start the process of photosynthesis and the sugar produced in the cell results in increase of osmotic pressure giving rise to endosmosis and solvent molecules move from higher to lower concentration.
✿Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called hydrostatic pressure, and defined as the pressure measured by a fluid, measured at a certain point within itself when at equilibrium.