Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day. Answer: Answer: 1. Give details of symplast route of water movement. (a) oxidation reaction Atmospheric pressure: In low atmospheric pressure, the rate of transpiration increases. The turgor pressure in the cells of stem and the roots are comparatively low and hence, the soluble organic solutes begin to flow en masse from mesophyll through the phloem to the cells of stem and roots along the gradient turgor pressure. Root pressure is absent in woody plants. Answer: Question 9. (b) increase of dissolved solutes in the solution. Fill the cavity with concentrated sugar solution and mark the initial level. (a) the rate of photosynthesis (b) ranslocation of food due to TP. (e) With reference to artificial cell state, the process is endosmosis or exosmosis? In stems of woody plants and trees, the epidermis is replaced by periderm because of secondary growth. Exosmosis in a plant cell leads to plasmolysis. Answer: Answer: Ans. In pure water, the addition of solute reduces its free energy and lowers the water potential value from zero to negative. Answer: Answer: Pulsation theory was proposed by: Question 25. Question 12. With the help of your teacher discuss the results. However, at very high – temperatures stomata closes because of flaccidity and transpiration stop. (c) (i) and (ii) only Question 3. (a) Steward Answer: There was no … The method of demonstration of endo – osmosis by potato Osmoscope: Instead of potato use beetroot or bottleguard and repeat the above experiment. Phenyl Mercuric Acetate (PMA), when applied as a foliar spray to plants: (d) The cell become more turgid. A . Question 6. Question 15. Place this setup in a beaker of pure water. Answer: In plants, such a pull is generated by the process of transpiration which is known as transpiration pull. (b) (i) and (iii) only. (d) Anti – transpirants reduce the enormous loss of wafer by transpiration in crop plants. Two hours and discuss with your teacher: Question 1. (d) Salisilic acid c. root pressure. (d) all the three above Two objections to starch – sugar inter conversion theory: Question 22. As electrons pass outward through electron transport chain there is a corresponding inward passage of anions. (c) (ii) and (iv) What will happen if an indoor plant is placed under fan and AC? The term solute denotes food material that moves in a solution. Capillary theory: Boehm (1809) suggested that the xylem vessels work like a capillary tube. Answer: The swelling of dry seeds is due to phenomenon called: There are three types of carrier proteins classified on the basis of handling of molecules and direction of transport. Main defects of the above theory are: Solution To Activity Root pressure does not account for the majority of water transport; most plants meet their needs by transpiration pull. Answer: Thus, the rate of water absorption is equal to the rate of transpiration. (d) All the above The gum will absorb large amount of water and swells. In this condition the net movement of water molecule will be zero. (i) Root pressure is absent in gymnosperms. Question 1. (c) three types of molecules are transported in opposite direction. Indicate the correct statement: An oxygen gradient responsible for oxidation at the outer surface of the membrane and reduction at the inner surface. This theory involves the symplastic movement of water. Answer: (c) Cuticular Explain it with examples. Therefore, soil water diffuses into root hair along the concentration gradient (endosmosis). According to this theory, the following steps are involved in the stomatal opening: Answer: (a) DPD = 10 atm; OP = 5 atm; TP = 10 atm Root pressure definition, osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Mention any two uses of anti – transpirants. Answer: Immerse in 100 ml of water. The capillary theory was suggested by: (c) Stoking Question 16. Root pressure is basically the idea that a plant's roots can either maintain a higher or lower pressure based on its surroundings. In the symplastic route, water has to cross plasma membrane to enter the cytoplasm of outer root cell; then it will move within adjoining cytoplasm through plasmodesmata around the vacuoles without the necessity to cross more membrane, till it reaches xylem. (b) (ii) and (iii) only Solute potential, otherwise known as osmotic potential denotes the effect of dissolved solute on water potential. But they must be balanced by the ions of opposite charge. MEDIUM. However, if new sugar solution is added in chamber “A”, the system will start to run again. 6. (d) Root pressur does not occur in spring. Give reasons. (ii) Continuity of the water column in the plant: An important factor which can break the water column is the introduction of air bubbles in the xylem. What are the types of transport based on the distance travelled by the materials? Read the values ans answer the following questions? Root canal therapy is a treatment used to repair and save a tooth that is badly decayed or infected. Although root pressures are probably more widespread than previously thought, they have never been recorded in gymnosperms (Milburn and (b) 1828 Question 1. (d) Dixon and Jolly What type of transpiration is possible in the xerophyte Opuntia? (c) Abscisic acid, Question 28. (c) Abscisic acid Question 14. (b) i – b; ii – c; iii – d; iv – a (c) i – d; ii – c; iii – a; iv – b, Question 36. Define active absorption of water. (d) (i) and (iv) It may, therefore, be mentioned that when transpiration is poor, the upward movement of water is affected by root pressure. When a woody or herbaceous plant is girdled, the sap contains high sugar containing exudates from cut end. Answer: This electrical balance or equilibrium controlled by electrical as well as diffusion phenomenon is known as the Donnan equilibrium. Answer: Anions are picked up by oxidized cytochrome oxidase and are transferred to other members of chain as they transfer the electron to the next component. Root pressure is totally absent in gymnosperms, which includes some of the tallest plants. Hence the transpiration is a “necessary evil” as stated by Curtis. (c) (iii) and (iv) only, Question 3. Your email address will not be published. 5. Question 1 . (d) Anti – transpirants reduce the enormous loss of wafer by transpiration in crop plants. In this process movement of water is reversed by applying pressure to force the water against a concentration gradient of the solution. Explain in detail about the cohesion tension theory proposed by Dixon and Jolly (1894). Answer: Guard cell becomes hypertonic and favours the entry of water from surrounding cells. Answer: However, Parker (1964) reported copious exudation from black birch in New England in October and November, after leaf fall. Merits: Question 8. (a) Ascorbic acid (c) Boehm, Question 20. Answer: (c) Boehm Furthermore, the fact that root pressures tend to be lowest when water loss from leaves (transpiration) is highest, which is exactly when plants most need water, shows that … Answer: There is no relationship between the ascent of sap and root pressure. Answer: Thus the value of solute potential is always negative. Question 7. Moreover plants withstand against scorching sunlight due to transpiration. (b) Lenticular (b) decreases the pH level. Question 23. Osmotic pressure of mesophyll cells and that of root hair do not confirm the requirements. (high solute and low solvent) placed in the water, it swells up due to turgidity. Answer: The crucial factor is apparently related to the age-old observation that sap flow requires warm days and cool nights. It is created by the secretion of ions into the xylem. The transpiration in plants is a “necessary evil” as stated by: This theory was proposed by Levit (1974) and elaborated by Raschke (1975). (iii) Transpiration pull or Tension in the unbroken water column: The unbroken water column from leaf to root is just like a rope. Define the term Imbibition. Question 6. (iv) Larger molecules diffuse faster than smaller molecules. B Trees . Keep this apparatus in bright sunlight and observe. Hypotonic (Hypo – low; tonic = solute): This is a weak solution (high sol vent / low or zero solute/ high Ψ) and it diffuses water out to other solutions. This process is called guttation and specialized structures (hydathodes) in the leaves are involved. (a) Anti – transpirants increases the loss of water by transpiration. 1. The discovery of enzyme phosphorylase in guard cells by Hanes (1940) greatly supports the starch – sugar interconversion theory. ... View Answer. (a) two different molecules are transported in opposite direction. As the air becomes dry, the rate of transpiration is also increased proportionately. Answer: They are: Question 3. What are the three types of wilting in plants? During root canal therapy, the pulp is removed, and the inside of the tooth is cleaned and sealed. Root pressure is retarded or become absent in. Chamber “A” contains highly concentrated sugar solution while chamber “B” contains dilute sugar solution. Higher values (e.g., 5-10 atm) are also observed occasionally. (d) Von Mohl, Question 26. 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