Water potential is equal to 
Water potential is defined as the difference between chemical potential of water at any point in a system and that of pure water under standard conditions. The unit of measurement of water potential is pascal, Pa (1 mega pascal, Mpa = 10 bars). It is represented by greek letter PSi (ψ). Water potential has two components solute potential which is always negative and pressure potential which is usually positive. Therefore water potential ψw is expressed as: ψw = ψs + ψp
Transpiration is least in 
Transpiration is a process of loss of water in the form of vapours from the aerial parts of the plants. Transpiration is inversely proportional to the atmospheric humidity. The rate of transpiration would be higher when humidity is low.
Phenyl mercuric acetate (PMA) results in 
Phenyl Mercuric Acetate (PMA) is an antitranspirant. Antitranspirants are compounds applied to the leaves of plants to reduce transpiration without affecting gaseous exchange. They are used on Christmas trees, cut flowers, newly transplanted shrubs, and in other applications to preserve and protect plants from drying out too quickly. They have ‘also been reportedly used to protect leaves from salt burn and fungal diseases.
Anti Transpirants are of two types: 1. Metabolic inhibitors 2. Film forming antitranspirants
Stomata open and close due to [1988, 2002]
Turgor pressure is the pressure that develops in a cell due to osmotic diffusion of water inside it and is responsible for pushing the membrane against cell wall. Stomata open under conditions of increased turgor pressure of guard cell and stomata get closed under conditions of decreased turgor pressure of guard cells. When turgid, they swell and bend outward. As a result, the stomatal aperture opens. When they are flaccid, the tension from the wall is released and stomatal aperture closes.
A bottle filled with previously moistened Mustard seeds and water was screw capped tightly and kept in a corner. It blew up suddenly after about half an hour. The phenomenon involved is 
The absorption of water by the solid particles of an adsorbent causing it to increase in volume without forming a solution is called imbibition.
The principal pathway of water translocation in angiosperms is 
Water movement occurs through the trachaery elements of xylem.
In soil, the water available for root absorption is [1991, 99]
After rain a portion of water percolates downwardly under the influence of gravity. It is not available to plants. Hygroscopic water is also not available for plants because soil particles hold water by strong attractive forces. Chemically bound water is combined with chemicals. Capillary water is present in narrow spaces of soil and is held in soil by capillary forces and is absorbed by root.
The most widely accepted theory for ascent of sap in trees is 
Transpiration pull and cohesion theory was put forward by Dixon and Jolly in 1894. According to this theory water rises due to the transpiration pull, continuity of water column and the cohesive power of water molecules from the lower part of the roots to the higher peaks of the trees.
Water movement between cells is due to 
Water is absorbed by a system having higher DPD from another system with lower DPD. The net force with which water is drawn into a cell is equal to the difference of osmotic pressure (OP) and turgor pressure known as diffusion pressure deficit (DPD).
DPD = OP – TP
Which of the following is used to determine the rate of transpiration in plants? 
Potometer is an apparatus used for measuring the rate of transpiration.
Guttation is mainly due to 
Loss of water from margins of leaves is called guttation. Guttation occurs when transpiration rate is very low as compared to rate of water absorption. Due to which root pressure is developed and water is pushed out through stomata like pores called hydathodes. It occur in more saturated atomosphere.
In terrestrial habitats, temperature and rainfall conditions are influenced by 
Transpiration is responsible for saturation of the atmosphere.
Conversion of starch to organic acids is required for 
Starch is converted to malic acid (organic acid) through the action of an enzyme phosphoenol pyruvate carboxylase (PEPC) under condition of high pH when most of the CO2 is utilized due to high photosynthetic rate during daytime.
At constant temperature, the rate of transpiration will be higher at 
The rate of transpiration is inversely proportional to the atmospheric pressure. Increased height above the sea level lower the atmospheric pressure and increases the rate of evaporation.
In guard cells when sugar is converted into starch, the stomatal pore 
When sugar is converted into starch, the osmotic concentration of guard cells fall and they lose water to adjacent cells and stomata closes.
Amino acids are mostly synthesised from 
a-ketoglutaric acid are the precursors of amino acid.
Which is produced during water stress that brings stomatal closure 
During scarcity of water in the soil, stress hormone abscisic acid is produced which brings about stomatal closure. ABA inhibits the uptake of K+ by the guard cells and promotes leakage of malic acid from guard cell. This result in loss of water from guard cell due to its lower osmotic potential. Guard cell become flaccid leading to closure of stomatal aperture. ABA also causes stomatal closure under high concentration of CO2 in the guard cells.
An adaptation for better gaseous exchange in plant leaves is 
Stomata present on lower surface of plant leaves effectively exchange gases without allowing much loss of water from the leaves.
Active and passive transports across cell membrane differ in 
Active transport always involves the expenditure of energy for the movements of substances against concentration gradient.
The closure of lid of pitcher in a pitcher plant, is due to 
Pitcher plant is an insectivorous plant which catches insects. The paratonic movements are induced in response to an external stimulus caused by insects due to which lids close and the insects are trapped inside the pitcher.
The movement of mineral ions into plant root cells as a result of diffusion is called
Osmosis is the movement of solvent particles from a region of low solute concentration to a region of high solute concentration through a selectively permeable membrane. Active absorption involves use of ATP.
With increase in the turgidity of a cell surrounded by water the wall pressure will 
Wall pressure is equal and opposite to the turgor pressure.
Bidirectional translocation of minerals takes place in 
Minerals can move upward and downward (bidirectional movement) as well as laterally in phloem. Phloem plays an important role in translocation of minerals.
The core metal of chlorophyll is 
A non ionic Mg atom is held in the centre of porphyrin (of chlorophyll) held by N atom of pyrrole ring.
Plants die from prolonged water-logging because 
Under water logged conditions roots die due to lack of air for respiration.