According to this theory lbllow ing factors play role in the ascent of sap. 10. Answer: (d) transpiration-cohesion theory of Dixon. This theory states that the. Strong cohesive force or tensile strength of water Options (a) capillarity (b) pulsatory movement of living tissue (c) role of atmospheric pressure (d) transpiration pull and cohesion. Capillary force theory. negative pressure or pull or suction is created in the leaves as a result of transpiration pulls the water upward. Transpiration Pull What is the driving force? •Godlewski (1884) proposed ‘relay pump theory… The ascent of sap in tall trees, however, is not possible by capillary force. 9. Cohesion Tension Theory of Ascent of Sap Dixon and John Jolly observed that transpiration, osmotic uptake of water by living cells, and hydration of cell walls (adhesion) create tension. The work was published by Dixon in book-form with a great wealth of experimental details in 1914. negative pressure or pull or suction is created in the leaves as a result of transpiration pulls the water upward. This theory states that the. Transpiration pull cohesion theory for ascent of sap in trees is most widely accepted. •These theories have been proposed by several workers viz., Godlewski (1884), Bose (1923) and Molish (1929). 3. The most widely accepted theory for movement of water through plants is known as the cohesion theory. This theory is very convincing and has now been widely supported by many work­ers. The theory states that transpiration pull or tension, cohesion property of water, and hydration of the cell walls (i.e., adhesion) are collectively responsible for the ascent of sap. Christian Wolf proposed this theory in 1873 and he suggests that water rises up in the narrow tubes of xylem vessels by surface tension. The most widely accepted theory of ascent of sap is . (D) Transpiration Pull and Cohesion of Water Theory: This theory was originally proposed by Dixon and Joly (1894) and greatly supported and elaborated by Dixon (1914, 1924). According to this theory lbllow ing factors play role in the ascent of sap. Correct Answer: transpiration pull and cohesion. This tension is relieved by an upward movement of water from below (ascent of sap), and the columns of water are being held together by cohesion. his theory %s as enunciated by Dixon (1910). Explanation: Cohesion and transpiration pull theory was proposed by Dixon and Jolly in 1894. Cohesion and Transpiration Pull Theory was first proposed by Dixon and Joly (1894) and is based on the following features: (i) Cohesion and Adhesion: Mutual attraction between water molecules is called cohesion. According to this theory, atmospheric pressure is responsible for as< of sap. The most widely accepted explanation for the ascent of sap in trees is (a) capillarity (b) atmospheric pressure (c) pulsating action of living cells (d) transpiration-cohesion theory of Dixon. This concept was proposed by Dixon and Jolly, 1884. Cohesion -tension theory was originally proposed by Dixon and Jolly (1894) and again put forward by Dixon (1914, 1924). It is based up on three basic assumptions which are cohesion in between water molecules, continuity of water column and transpiration pull. Cohesion-tension or Cohesion and transpiration pull theory . Atmospheric pressure theory. This theory was proposed by Dixon according to this theory a number of forces responsible for upward movement of sap in plants. (d) COHESION TENSION THEORY. idea of cohesion-tension mechanism of ascent of sap. This theory is based on the following features: i. his theory %s as enunciated by Dixon (1910). 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