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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 of plants. [ 1][ 2] It was proposed by Ernst Münch, a German plant physiologist in 1930. [ 3] Organic molecules such as sugars, amino acids, certain hormones, and messenger RNAs are known to be ...
Pressure flow hypothesis: Sugars produced in the leaves and other green tissues are kept in the phloem system, creating a solute pressure differential versus the xylem system carrying a far lower load of solutes- water and minerals. The phloem pressure can rise to several MPa, [12] far higher than atmospheric pressure. Selective inter ...
Biological fluid Dynamics (or Biofluid Dynamics) involves the study of the motion of biological fluids (e.g. blood flow in arteries, animal flight, fish swimming, etc.). It can be either circulatory system or respiratory systems. Understanding the circulatory system is one of the major areas of research. The respiratory system is very closely ...
"Bulk flow" is the movement/flow of an entire body due to a pressure gradient (for example, water coming out of a tap). "Diffusion" is the gradual movement/dispersion of concentration within a body with no net movement of matter. An example of a process where both bulk motion and diffusion occur is human breathing. [2]
In nonideal fluid dynamics, the Hagen–Poiseuille equation, also known as the Hagen–Poiseuille law, Poiseuille law or Poiseuille equation, is a physical law that gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section. It can be successfully applied to ...
In the life sciences, mass flow, also known as mass transfer and bulk flow, is the movement of fluids down a pressure or temperature gradient. [1] As such, mass flow is a subject of study in both fluid dynamics and biology. Examples of mass flow include blood circulation and transport of water in vascular plant tissues.
The clouds in this image of the Amazon Rainforest are a result of evapotranspiration. Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant. [ 1]
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H +) across a membrane during cellular respiration or photosynthesis . An ion gradient has potential energy and can be ...