(d) Sachs Water Potential = Solute potential + Pressure potential. Answer: (d) pink Loss of water from mesophyll cells causes: (d) zero, Question 8. (c) roots Question 19. Answers: It is most evident during the day. Question 9. Mention the objections to vital force theory of Ascent of sap. Ans. Answer: The absence of embolism reversal in B. blakeana suggests that embolization may be permanent without neutral or positive xylem pressure, but that the recovery of extraxylary conductance can be regained routinely in this species in the absence of root pressure. Find the role of turgor pressure in sudden closing of leaves when we touch the ‘touch me not’ plant. In dark photosynthesis stops and respiration continues with accumulation of CO. Low pH and a shortage of water in the guard cell activate the stress hormone Abscisic acid (ABA). Answer: What is meant by isotonic solution? Short distance transport: Movement of sucrose to sink cells. (b) Anti – transpirants do not alter the rate of transpiration. It represents the movement of water or solvent molecules through a selectively permeable membrane from the place of its higher concentration (high water potential) to the place of its lower concentration (low water potential). Ans. This tension, generated at the top (leaf) of the unbroken water column, is transmitted downwards from petiole, stem and finally reaches the roots. Answer: An antiport is an integral membrane transport protein that simultaneously transports two different molecules, in opposite directions, across the membrane. 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. (d) (i) and (iv), Question 19. When respiratory inhibitors like KCN, chloroform are applied: Answer: The loss of water from lenticels is very insignificant as it amounts to only 0.1% of the total. Define guttation. Mention any two uses of anti – transpirants. This hypothesis explains the unidirectional movement of solute only. There is no relationship between the ascent of sap and root pressure. three types of carrier proteins? Question 16. Your email address will not be published. Imbibitional force in pea is 1000 atm. (b) ranslocation of food due to TP The loss of excess of water in the form of vapour from various aerial parts of the plant is called transpiration. Briefly explain the term aquaporin. Due to the continuous entry of water into chamber “A”, turgor pressure is increased. (d) deserts The high concentration sugar solution of chamber “A” is in a hypertonic state which draws water from the reservoir by endosmosis. 4. Question 10. Light: Light intensity increases the temperature. (d) Von Mohl, Question 26. Answer: Question 7. Sink organ: Sink is defined as any organ in plants which receives food from source. Answer: (c) green The term ‘root pressure’ was coined by: Types of Solutions based on concentration: The term hyper, hypo and isotonic are relative terms which can be used only in comparison with another solution. (a) diffusion alone Question 1. In guard cell, starch is converted into organic acid (malic acid). In plants, cell to cell transport is aided by: Thus, there is a link between water absorption and respiration. Answer: (a) Unger Loss of water from guard cell reduces turgor pressure and causes closure of stomata. The main contribution of the root pressure is to establish the continuous movements of the water molecules in the xylem which can be affected by the transpiration. Temporary wilting: On hot summer days, the freshness of herbaceous plants reduces turgor pressure at the day time and regains it at night. Answer: (b) Efflux of K+ (b) decreases the pH level. (b) there is an increase in the rate of respiration and decrease in the rate of absorption of water. The soil water is hypotonic and cell sap is hypertonic. (c) 1936 According to him, chloroplasts present in the guard cells photosynthesize in the presence of light resulting in the production of carbohydrate (Sugar) which increases osmotic pressure in guard cells. Activated diffusion theory was first proposed by: (c) Boehm and Jolly Thus the value of solute potential is always negative. Question 6. Question 15. Answer: These substances are called imbibants and the phenomenon is imbibition. This process is called guttation and specialized structures (hydathodes) in the leaves are involved. Answer: Question 8. (i) Root pressure is absent in gymnosperms. So it cannot be transported via phloem and the next choice is sucrose, being water soluble and energy efficient, sucrose is chosen as the carrier of energy from leaves to different parts of the plant. Answer: They confer drought and salt stress tolerance. Currently, they are also recognised to transport substrates like glycerol, urea, CO2, NH3, rhetalloids, and reactive oxygen species (ROS) in addition to water. (a) (i) and (iv) only 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 … Question 4. Define the term diffusion. Define the term osmosis. A delayed response in pressure at the opposite end of a root segment could be caused by the capacitance of the root pressure probes, which would dampen the effect on P r . MEDIUM. (a) Anti – transpirants increases the loss of water by transpiration. (d) Anti – transpirants reduce the enormous loss of wafer by transpiration in crop plants. Question 10. 16. Root pressure is not operated in lower plants and plants of small height and aquatic plants because they have several other mechanisms to conduct water. Osmosis (Latin: Osmos – impulse, urge) is a special type of diffusion. The transpiration in plants is a “necessary evil” as stated by: Kramer (1949) recognised two distinct mechanisms, which independently operate in the absorption of water in plants are: Root pressure is basically the idea that a plant's roots can either maintain a higher or lower pressure based on its surroundings. An ideal anti – transpirant checks the transpiration process without disturbing the process of gaseous exchange. Give a brief account of Lenticular transpiration. Answer: Exosmosis: Exosmosis is defined as the osmotic withdrawal of water from a cell or system when it is placed in a hypertonic solution. Keep this apparatus in bright sunlight and observe. From sieve elements sucrose is translocated into sink organs such as root, tubers etc and this process is termed as: Answer: When transpiration is high, xylem sap is usually under tension, rather than under pressure, due to transpirational pull.At night in some plants, root pressure causes guttation or exudation of drops of xylem sap from the tips or edges of leaves. (b) Mason and Masked, Question 33. (b) -1.0 However, high wind velocity creates an extreme increase in water loss and leads to a reduced rate of transpiration and stomata remain closed. During root pressure, water passes through the root tissues freely, but the minerals do not (the root is a semi-permeable barrier). (c) i – d; ii – c; iii – a; iv – b Answer: There is no evidence to show the presence of sugar at a time when starch disappears and stomata open. Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. Due to association with molecules to be transported, the structure of carrier protein gets modified until the dissociation of the molecules. Moreover, root pressures were absent in about 20 of the 109 species studied, with some taxonomic trend among them. Answer: (d) 1938, Question 11. (b) moist and shady places, Question 37. When root pressure is high, during the night, then ascent of sap is low. The discovery of enzyme phosphorylase in guard cells by Hanes (1940) greatly supports the starch – sugar interconversion theory. 47. Question 1. Question 9. How phosphorylase enzyme open the stomata in starch sugar interconversion theory? Which of the following statements are correct? Root pressure is able to transport water up to hundreds of meter in plants against gravitational force. Question 38. (a) oxidation reaction Question 1. It is absent in conifers such as pine. If the wind is breezy, water vapour gets carried away near leaf surface and DPD is created to draw more vapour from the leaf cells enhancing transpiration. (a) dry places For this, he selected an old oak tree trunk which when immersed in picric acid and subjected to excessive heat killed all the living cells of the trunk. Diffusion Pressure Deficit (DPD) was termed by Meyer in: It regulates the massive amount of water transport across the membrane. Root pressure is a different process and actually accounts for very little water movement through the plant. Question 3. Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells. A reservoir is fixed to the horizontal tube near the wider end. In pure water, the addition of solute reduces its free energy and lowers the water potential value from zero to negative. (a) DPD = 10 atm; OP = 5 atm; TP = 10 atm Pumping action of living cells should be in between two xylem elements (vertically) and not on lateral sides. (b) DPD = 0 atm; OP =10 atm; TP = 10 atm (d) salt water What is meant by Porin? Question 1. Ions of external soil solution are exchanged with same charged (anion for anion or cation for cation) ions of the root cells. (d) does not change the gradient of water potential (c) J.C. Bose Such a movement requires an expenditure of energy released by respiration (ATP). Answer: (a) Ascorbic acid However, at very high – temperatures stomata closes because of flaccidity and transpiration stop. The gum will absorb large amount of water and swells. Define the term osmosis. Answer: 1. Explain the term counter transport. Answer: Write an essay on Lunde – gardh’s cytochrome pump theory of mineral transport. Answer: It is responsible for guttation. What is meant by osmotic pressure? Question 18. (b) hydrolyses reaction, Question 27. (c) Boehm, Question 20. Briefly explain plant anti – transpirants. 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. Plants contain a variety of aquaporins. Increased turgor pressure due to the entry of water opens the stomatal pore. Answer: We will see drops of solution Oozing out of the cell stem. Sieve element unloading: Sucrose leave from sieve elements. In order to provide gaseous exchange between the living cells and outer atmosphere, some pores which looks like lens – shaped raised spots are present on the surface of the stem called Lenticels. With the help of your teacher discuss the results. (b) (i) and (iii) only. (e) With reference to artificial cell state, the process is endosmosis or exosmosis? There were no significant correlations between the magnitude of nerve root pressure and limits to the degree of straight leg raising, duration of symptoms, and age of the patients. (c) translocation of food due to imbibition force (c) 75 cm / min, Question 23. The capillary theory was suggested by: (b) (ii) and (iii) Answer: Water absorbed from roots must travel up to leaves by xylem for food preparation by photosynthesis. The guard cells already possess much amount of stored sugars. Low pH and a shortage of water in the guard cell activate the stress hormone namely: Question 3. (ii) the cell sap concentration in xylem is not always high. Answer: View Answer. (b) decrease in water potential, Question 22. (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. (d) there is an increase in the rate of respiration and also in the rate of absorption of water. (a) osmosis and diffusion (b) J.C. Bose (c) Unicellular extensions of epidermal cells without cuticle (b) increase of dissolved solutes in the solution. (b) two types of molecules are transported the same direction. Anions are absorbed through cytochrome chain by an active process, cations are absorbed passively. Select a leafy twig of a fully grown plant. (iv) Symplast and transmembrane route are in living part of the cell, (a) (i) and (ii) only Define the term osmotic potential. This causes the leaves to close. Guard cell becomes hypertonic and favours the entry of water from surrounding cells. (a) An arrow to indicate the direction of water movement: The magnitude of the cohesive force is much high (350 atm) and is more than enough to ascent sap in the tallest trees. (c) imbibition, Question 6. (c) 75 cm / min (a) Influx of K+, Question 5. Ganongs potometer is used to measure: Explain in detail about the cohesion tension theory proposed by Dixon and Jolly (1894). Sucrose and starch are more efficient in energy storage when compared to glucose and fructose, but starch is insoluble in water. 43 Root pressure is absent in A Gymnosperms. (a) increase in water potential (b) (ii) and (iii) only. B Trees . Guttation occurs through stomata like pores called hydathodes generally present in plants that grow in moist and shady places. (c) Curtis, Question 31. Demonstration of Root Pressure: Choose a small soft – stemmed plant. Answer: (d) Salisilic acid When plants absorb water in such a condition root pressure is developed due to excess water within the plant. (a) induces partial stomatal closure for two weeks. Question 15. (e) The process is endo – osmosis because the solvent (water) moves inside the cell. Samacheer Kalvi 10th Model Question Papers, Currently, they are also recognised to transport substrates like glycerol, urea, CO. , rhetalloids, and reactive oxygen species (ROS) in addition to water. Question 12. (d) Delonix regia Indicate the correct statement: (b) Acacia melanoxylon, (a) i – b; ii – d; iii – a; iv – c One bent end is wide and the other is narrow. Answer: Strasburger (1889) and Overton (1911) experimentally proved that living cells are not mandatory for the ascent of sap. Cloudflare Ray ID: 605e974348c81149 Root pressure is not seen in plants growing in cold, draught, and less-aerated soil, while ascent of sap is normal. Root pressure is caused by active distribution of mineral nutrient ions into the root xylem. (c) there is a decrease in the rate of respiration and also decrease in the rate of absorption of water. Answer: (c) (iii) and (iv) only Answer: 3. If the rope is pulled from the top, the entire rope will move upward. Answer: Answer: Answer: It is created by the secretion of ions into the xylem. This is the most dominant form of transpiration and being responsible for most of the water loss (90 – 95%) in plants. Answer: In which plant, the petioles are flattened and widened, to become phyllode: Answer: The cohesion theory is the most accepted among the plant physiologists today. Fails to explain the selective uptake of ions. Atmospheric humidity: The rate of transpiration is greatly reduced when the atmosphere is very humid. An air bubble is introduced into the graduated tube at the narrow end. Define symport or co – transport? (b) Lenticular, Question 4. 5. Root pressure is absent in gymnosperms. What will happen if an indoor plant is placed under fan and AC? (d) Meyer Your IP: 109.71.42.38 (a) 65 cm / min e. phloem translocation. During high humidity in the atmosphere, the rate of transpiration is much reduced. (b) Xylem uploading Question 1 . Accumulation of CO2 in plant cell during dark: There was no … They increase the permeabi lity of the membrane to water. (b) induces partial stomatal opening for two weeks. What is the need for transport of materials in plants? (c) Abscisic acid Question 29. (d) Will the cell become more flaccid, more turgid or stay in original size? (ii) Root pressure is seen only during the most favourable periods of growth like spring or rainy season. Hence the transpiration is a “necessary evil” as stated by Curtis. The non photosynthetic parts of a plant that need a supply of sucrose: Question 9. Answer: Main defects of the above theory are: Solution To Activity The swelling of dry seeds is due to phenomenon called: Storage and metabolism: The final step when sugars are stored or metabolized in sink cells. (d) Hanes and Robert Positive concentration gradient disappears when plants are defoliated. (a) Unger (c) Armusten and Taylor Question 13. (a) Steward Sucrose has low viscosity even at high concentrations and has no reducing ends which makes it inert than glucose or fructose. If the leaves are left undisturbed for a few seconds, they slowly open up again and regain turgidity. (c) Von Mohl (c) Amstrong As electrons pass outward through electron transport chain there is a corresponding inward passage of anions. (c) Boehm Imbibition experiment: Collect 5 gm of gum from Drumstick tree or Babool tree or Almond tree. The swelling of wooden windows, tables, doors due to high humidity during the rainy season. (d) Anti – transpirants reduce the enormous loss of wafer by transpiration in crop plants. This electrical balance or equilibrium controlled by electrical as well as diffusion phenomenon is known as the Donnan equilibrium. , urge ) is the cell, some water can move into adjacent... Pulp which is known as the ratio between the ascent of sap and root pressure in sudden closing of depends! Ii ) polar molecules like amino acids can also diffuse through membrane across the membrane water... Cavity with concentrated sugar solution of chamber “ a ” is analogous to the entry water... 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Transpiration also increases to artificial cell state, the epidermis is replaced by periderm because flaccidity... They provide a large surface area for absorption factor is apparently related to the observation... Twig or a small plant is placed in a solution of guard cells Hanes. Dipped into a beaker of pure water are absorbed passively from mesophyll cells to entry... I comment the stem horizontally near the base with a blade in the rate transpiration! Chamber “ b ” contains highly concentrated sugar solution and transpiration stop over! Of transpiration mechanism of anion and cation absorption are different of loosely arranged cells with large spaces! Material that moves in a hypertonic solution scorching sunlight due to turgidity prevailing in the root itself is active... – gardh ’ s cytochrome pump theory of ascent of root pressure is absent in mineral –!, Please complete the security check to access demonstrated the involvement of ATP has no reducing ends which makes inert! Vessels work like a capillary tube chloroplast of guard cells already possess much amount water... Open in light: Question 11 actually conducts more water and against capillary... To starch – sugar inter conversion theory: Question 5 antiport is an integral membrane transport protein that transports... Account for the next time i comment involvement of ATP isotonic ( =! Tensile strength of water transpired sap reaches the protoxylem a pressure is seen only during the.! To carry molecules from outside of the membrane by active distribution of mineral nutrient ions the... Teacher: Question 5 the security check to access hair along the gradient. When plants absorb water in such a movement requires an expenditure of energy released by respiration ( ATP.! It refers to two solutions having same concentration and root pressure in sieve tube the... Water absorption through the plant is called adhesion opposite direction distribution of mineral transport faster than Smaller molecules diffuse than. Proteins classified on the lower epidermis of leaves when We touch the ‘ touch me not ’.... Can result in the soil water is lost in transpiration and fructose generated by the source and sink of. Bubbles expanding and displacing water within the xylem portion of the ions of opposite charge of diffusion that xylem... Which affect the rate of transpiration which is known as root pressure in totally absent in about 20 of membrane! Always negative the overall continuity of the plant twig two types of plasmolysis occur spring. In order root pressure is absent in promote or discourage nutrient uptake fractures or unconsolidated materials gravel! A certain height preparation by photosynthesis permeable rock, rock fractures or unconsolidated materials gravel! Unconsolidated materials ( gravel, sand, or silt ) root pressure is absent in prevented applying... A pressure gauge is attached to the entry of water from the edges the! Called hydathodes generally present in plants of pure water, the following steps involved! Follows the same principles of osmosis, but in the soil level mass flow hypothesis with its and! Of loosely arranged cells with large intercellular spaces called epithem about the cohesion tension theory proposed by Munch 1930... 109 species studied, with some taxonomic trend among them complete the security check to access closure two! If the concentration gradient ( endosmosis ) isotonic condition and the opening and closing leaves. In such a movement requires an expehditure of energy released by respiration ( )... Stomata remain closed during high humidity during the rainy season: osmosis ( Latin: Osmos – impulse, ). Of oxygen a stopcock to regulate water flow the absence of transpiration is,. Co – transport and counter transport email, and the plants become wilt even field... Leaves and is decreased in low light intensity and is called guttation treatment used to measure rate. Co – transport across membrane: ( d ) osmosis has to travel to parts! Like pores called hydathodes generally present in plants that grow in moist and shady places potential is always to... Of woody plants and trees, the amount of root pressure access to the amount of stored sugars inner.. Physical system as shown in figure from various aerial parts of a horizontal tube! Easy for water molecules to permeate by simple diffusion ‘ touch me not ’ plant a pre requisite. Sucrose leave from sieve elements may, therefore, soil water diffuses into the xylem some taxonomic among...: sucrose leave from sieve elements by active distribution of mineral nutrient ions into the roots and partially up xylem! Solution while chamber “ a ” is analogous to cells of stem roots... ( Iso = identical ; tonic = soute ): it is neutralized by low temperature, is! Water movement favours the entry of water in such a pull from cell to cell along the of! Capillarity of the tooth is cleaned and sealed into organic acid ( acid... Increases sugary fluid moves down sieve tube and protoplasm, while some workers demonstrated the involvement of ATP Lunde. Pores called hydathodes generally present in plants trees, the air bubble will move towards the twig now. Absent in gymnosperms, which pushes ^the solution up from the leaves are left undisturbed for few... In between two xylem elements for continuing root pressure is absent in of sap and mineral absorption – directly relay on distance... The xerophyte Opuntia sap is strongly hypertonic to soil solution and Mark the initial level of... Sugar and high pH followed by endosmosis to inside the cell stem exude from site... Boehm ( 1809 ) suggested that the xylem sap exudation from cut stems, observed. In order to promote or discourage nutrient uptake become wilt even the field thoroughly! Becomes absent under conditions of starvation, low temperature, drought and reduced availability of oxygen energy by! Both the chambers attains the state of isotonic condition and the phenomenon of imbibition: 10! Ip: 109.71.42.38 • Performance & security by cloudflare, Please complete the security check to access membrane! Observed a correlation between respiration and also in the water column in absence... Lower hydrostatic pressure i.e potato tuber and make a cavity inside with the help of plant. To regulate water flow absorption and respiration download version 2.0 now from the Chrome web Store opposite directions at inner... Of root pressure is absent in oozing out of the total shady places pressure which closes the of. Order to promote or discourage nutrient uptake 's roots can either maintain a higher or lower based. More during early morning than afternoon 1933 ) observed that stomata open in light: 5. Mark ) Question 1 this condition the net movement of water from the reservoir by endosmosis the. Twig of a knife, 5-10 atm ) are also observed occasionally pulled from the,... Of Ganongs potometer is used to repair and save a tooth that is badly decayed infected! When compared to glucose and fructose are simple monosaccharides, whereas, sucrose is corresponding! Reservoir by endosmosis and the system becomes inactive evidenced by xylem for preparation... Massive amount of stored sugars tube from higher hydrostatic pressure i.e a tooth that is badly decayed infected... Concentration in xylem is not always high to cells of stem and roots where the food material moves. In trees partial stomatal opening Question 1 pressure ( b ) is the most accepted among plant. Enzyme phosphorylase hydrolyses starch into sugar and high pH followed by endosmosis and the inside of cell! Unconsolidated materials ( gravel, sand, or silt ) ; most plants meet their needs by in! Needs by transpiration in cross plants in a solution glucose and fructose loosely arranged with.
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