Differentiate between guttation and transpiration.

1. Differentiate between guttation and transpiration.(2003)
Guttation : Plants which grow in moist, warm soil undre humid conditions often have droplets of water along the margin' of their leaves. rhis is also a form of water loss from the plants. The loss of water from the leaves in the form of water drops through specialized structures is called guttation. When water absorption greatly exceeds transpiration, water comes out through specialized structures called hydathodes. Hydathodes are. generally found at the tip of the veins of leaves which exhibit guttation. The guttation liquid is out pure water..
Transpiration The process of loss of water from the plants in the form of vapour through stomata is known as transpiiation. Stomata are distributed throughout the leaves, and they control the rate of transpirsrtion by closing and opening mechanisms. Transpirational water is pure in nature
2. What is water potential ?
The difference between the free energy of water molecules of pure water and the energy of water In any other system in solution or plant is called water profential. It is denoted by the letter Psi (sp ). Water potential is measured in 'bars'. Psi of pure water is zero. the common measurement unit of water potential is pascal, Pa (1 megapascal, Mpa = 10 bars).
3. Define-DPD.
Diffusion pressure of a solution is always lower han its pure solvent. The difference between the diffusion pressure of the solution and its solvent at a particular temperature aria atmospheric-conditions is ~ calledDPD. DPD or diffusion pressure deficit is equal in quantity (free energy) to water potential but opposite in sign.

21. Name the three theories of water translocation.
The three theories are (1) Root pressure theory
(2) Capillary theory and (3) Cohesion theory.
22. What is plasmolysis ?
The shrinkage of vacuole and protoplast causing the plasma mernbrance to fold inward and move ,away from the cell wall due to exomsmosis, when the cell is placed in a lypertonic solution is called plasmolysis.
23. What is transpiration ?
Loss of water in the form of watervapour from plant surface to the atmosphere is called transpiration. Transpiration occurs mainly from leavesthrough stomata.
24. What is reverse osmosis ?
By giving additional to an osmotic system the movement of solvent molecules from a region of their lesser 'concentration to their higher concentration occur. This is called reverse osmosis. The process of reverse osmosis is used for removing salts from saline water.
25. Define osmosis.
Osmosis is the movement of water molescules through a semi - permeable membrane from a region of higher concentration of water to a region of lesser concentration when these two are separated by it.
26. What are the chief component factors which affect the water potential in a system ?
Water potential can be expressed as atotal of its individual component ie,. = is + They.,are the effect of solutes, pressure and gravity respectively.
27. What is the importance of imbibition ?
Imbibition helps in the germination of seeds, movement of water from sell to cell and the ripening of seeds. In addition to this it carries out the warping of wooden frames in rainy season.
28. Define root pressure.
The movement of water from the soil into the root hair and then to the xylem cells with lower water potential generates pressure in the root. This pressue is called root pressure. Root pressure pushes the water up the xylem vessels.
2 . What is meant by 'ascent of sap' ?
Water and minerals are conducted upwards in plants against the gravitational force. This upward conduction of water froth the roofs to the aerial organs through the system is termed ascent of sap.
III. SHORT ANSWER TYPE QUESTIONS
30. Define the following.
(a) The matric potential (b) Solute potential
(c) Pressure potential
(a) Matric potential is the component of water potential influenced by the presence of matric such as cell wally soil, protoplasm etc.
•(b) Solute potential is the amount by which the water is reduced as a result
of presence of solutes. It is other wise called osmotic potential.
(c) Pressure potential is the pressure exerted by protoplasm on the cell wall (wall pres'sure)
31. What are the internal factors which control the absorption of at r from the soil by the root hair ?
Water absorption takes place mainly by two processes. Active absorption by root pressure and passive absorption by transpiration pull. Root pressure and passive absorption by transpiration pull. Root pressure developed in root cortex pushes water up through the xylem Transpiration of water from leaves causes a pulling force as thp water column is continuous from root to leaves. This also causes upward movement of water.