E) Sugar transport does not require energy. According to Annual Review of Plant Biology, Water and sucrose flow up the stem. Before moving into the source cells present in the phloem, the prepared food is converted into sucrose. PHLOEM PRESSURE AND THE MÜNCH HYPOTHESIS: THEORY According to Münch (1927), long-distance transport is driven by osmotically generated hydrostatic pressure (phloem pressure). At the regions of lower pressure, sink cells remove the sucrose by active transport. The evolutionary journey of plants onto land involved the differentiation of the plant body into decentralized organs, such as leaves, roots, stem, and branches. Before moving into the source cells present in the phloem, the prepared food is converted into sucrose. The phloem tissue is the principal sugar conductive tissue in plants. 8. 29) According to the pressure-flow hypothesis of phloem transport, A) solute moves from a high concentration in the "source" to a lower concentration in the "sink." The flow is generated by osmosis. According to mass or passive flow hypothesis, two features are important for phloem transport of substances. It involves continuous entry of sugar molecules at the source and exit at the sink by active transport, together with the entry of water by osmosis into the source and exit out of the sink. The hypothesis describes import rate (Rf) of a nutrient as: (1) R f = L p (P source − P sink) A C Before moving into the source cells present in the phloem, the prepared food is converted into sucrose. Osmotic pressure is maintained low at the sink. 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. Companion cells control the rate and direction of movement of phloem sap. Photoassimilates and other solutes enter the source end of the sieve tube and attract water by osmosis. Which is the most abundant solute in phloem sap? • The pressure–flow hypothesis states that solutes (such as dissolved sugars) move in phloem by means of a pressure gradient—that is, a difference in pressure • The pressure gradient exists between the source, where the sugar is loaded into phloem, and the sink, where the sugar is removed from phloem. According to pressure flow mechanism water containing sugar in solution flows under pressure through the phloem. What are the components of phloem sap? phloem pressure and the mÜnch hypothesis: theory According to Münch (1927) , long-distance transport is driven by osmotically generated hydrostatic pressure (phloem pressure). Over 80 years ago, Ernest Münch (1930) proposed the now widely accepted mechanism for phl… a) concentration gradient. It is the aim of this paper to construct a mathematical model based on the Münch pressure–flow hypothesis that can reproduce these qualitative observations of phloem transport. According to the pressure-flow hypothesis, food is prepared in the plant leaves in the form of glucose. Water moves from the xylem vessels into the adjacent phloem, thereby increasing the hydrostatic pressure in the phloem. Mass flow hypothesis? Osmotic pressure rises and phloem SAP moves from an area of higher osmotic pressure to the area of low pressure. According to the pressure-flow hypothesis of phloem transport, _____ asked Aug 24, 2015 in Biology & Microbiology by Beenx A) solute moves from a high concentration in the source to a lower concentration in the sink 2. There are different evidences that support the hypothesis. The relevant points of pressure-flow mechanism are as follows: 1. So far, this widely accepted Münch theory has … Which one of the following statements about transport of nutrients in phloem is false? As the sink cells pull the solute out of the phloem, water leaves the phloem by osmosis, passing to neighboring tissues that have higher solute concentrations. Long distance transport in plants occurs in sieve tubes of the phloem. According to the pressure-flow hypothesis of phloem transport, _____. At present, it is generally agreed that P protein agglomerations are preparation artifacts due to injury, the lumen of sieve tubes is free of obstructions, and phloem flow is driven by an osmotically generated pressure differential according to Münch's classical hypothesis. Name the vascular tissue which transports sucrose in plants. The primary sources are mature leaves. c. the pressure in the phloem of a root is normally greater than the pressure in the phloem of a leaf. B) water is actively transported into the "source" region of the phloem to create the turgor pressure needed. The pressure flow hypothesis of phloem transport provides a powerful tool to identify key control points of seed loading (see Figure 3). Water moves from the xylem vessels into the adjacent phloem, thereby increasing the hydrostatic pressure in the phloem. Besides water, sugars are one of the most important components involved in this transport. Name the process by which sucrose is moved to companion cells and sieve tube cells of the phloem according to the pressure flow hypothesis. a. solute moves from a high concentration in the source to a lower concentration in the sink b. the pressure of the phloem of a root is normally greater than the pressure in the phloem of a leaf c. the formation of starch from sugar in the sink increases the osmotic concentration d. water is actively transported into the "source" region of the phloem to create the turgor pressure needed. These organs are interconnected at the whole-plant level by long-distance transport. Now that we've covered sinks and sources, let's look at the pressure flow hypothesis. See Section 35.4 (Page 739) . So, according to Munch’s hypothesis the flow through the sieve tubes is passive, although there is evidence of involvement of metabolism in bulk flow. According to the pressure flow hypothesis, food is prepared in the plant leaves in the form of glucose. At the sink again active transport is required to move the sugar out of the phloem SAP into the cell where the sugar is used to release energy by the process of respiration. sucrose glucose starch amylose 9. Answers: 1. b) phloem translocation. According to the pressure flow hypothesis of phloem transport, V 03:59 Biology According to the pressure flow hypothesis of phloem transport, A) solute moves from a high concentration in the source to a lower concentration in the sink. According to the pressure-flow hypothesis of phloem transport, _____. It was proposed by Ernst Munch, a German plant physiologist in 1930. According to Mass flow hypothesis, mass flow of solute from source to sink is due to . Pressure-Flow Theory for Nutrient Transfer. 2/27/2018 MasteringBiology: Ch 35 HW 1/1 ' Ù Part A According to the pressure­flow hypothesis, which direction are sucrose and water flowing in the phloem when roots are sources and leaves are sinks? d) osmosis and diffusion . An active removal of … b) turgor pressure gradient. Water moves from the xylem vessels into the adjacent phloem, thereby increasing the hydrostatic pressure in the phloem. Ans:- According to the pressure flow hypothesis, food is prepared in the plant leaves in the form of glucose. According to Pressure flow hypothesis, the major force responsible for mass transfer of solute from source to sink is diffusion solute moves from a high concentration in the source to a lower concentration in the sink Which one of the following statements about transport of nutrients in phloem is correct? [citation needed] The pressure flow hypothesis proposes a mechanism for phloem sap transport, [citation needed] although other hypotheses have been proposed. Ü View Available Hint(s) Water and sucrose flow down the stem. The pressure-flow hypothesis visualizes a steady, unidirectional flow of sugar solution through living sieve elements. According to the pressure flow hypothesis, food is prepared in the plant leaves in the form of glucose. Secondly, concentration gradients of organic solutes are proved to be present between the sink and the source. Before moving into the source cells present in the phloem, the prepared food is converted into sucrose. e. solute moves from a high concentration in the "source" to a lower concentration in the "sink." (leaves) II. Firstly, there is an exudation of solution from the phloem when the stem is cut or punctured by the mouthparts of an aphid, a classical experiment demonstrating the translocation function of phloem, indicating that the phloem sap is under pressure. It is generally believed that an osmotically generated pressure gradient drives the phloem mass flow. Photoassimilates and other solutes enter the source end of the sieve tube and attract water by osmosis. Phloem sap is thought to play a role in sending informational signals throughout vascular plants. Glucose is produced by photosynthesis in the mesophyll cells of the green leaves, some of which is converted into nonreducing sugar, i.e., sucrose. c) osmosis. Water moves from the xylem vessels into the adjacent phloem, thereby increasing the hydrostatic pressure in the phloem. According to the pressure flow hypothesis of phloem transport, solute moves from a high concentration in the "source" to a lower concentration in the "sink." Thirdly, when viruses or growth chemicals are applied to a well-illuminated (actively photosynth… After sugars are produced in photosynthesis, these sugars must be transported to other parts of the plant for use in the plant's metabolism.Part of the pressure-flow theory is that the sucrose produced is moved by active transport into the companion cells of the phloem in leaf veins. kvargli6h and 50 others learned from this answer "The movement of water into a nutrient-rich region of the phloem decreases the pressure in that region" is the statement that is not true according to the pressure-flow hypothesis. The correct option among all the options that are given in the question is the fourth option or the last option. 10. Pressure Flow Hypothesis. Munch postulated that solute movement occurred in the phloem along a turgor pressure gradient from source to sink. According to the pressure-flow hypothesis, the sugar concentration gradient promotes the flow of water into the phloem, resulting in the generation of pressure. Thank you :))) 10 points ^_^ The active (energy driven) transport of sugars and other solutes into the sieve types in sources areas. The transfer of sugar from leaf mesophyll to sieve elements of phloem is called osmosis phloem loading phloem unloading sink loading 10. ... MCQ munch hypothesis, MCQ phloem transport answers, mcqbiology, Multiple choice plant transport, Source sink concept. Water flows down the stem, and sucrose flows up the stem. In angiosperms, increasing evidence shows the pressure-flow hypothesis, formulated by Ernst Münch in 1930 [1 ••], to adequately explain the mechanism of phloem transport [].However, its applicability to gymnosperms is more debated than ever. 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