The tension created by transpiration “pulls” water in the plant xylem, drawing the water upward in much the same way that you draw water upward when you suck on a straw. Cohesion (water sticking to each other) causes more water molecules to fill the gap in the xylem as the top-most water is pulled toward the stomata. Answer : (a)

Cohesive force of water is due to the hydrogen bond between the water molecules. It allows the liquid molecules to resist separation. It contributes in ascent of sap due to the following phenomena Answer : (b)

Answer : (b)

Graham's law states that the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight. Answer : (a)

The force responsible for raising water in 100ft tall plant is transpiration pull Forces generated by transpiration can create pressure sufficient to lift water even upto height of 130 m Answer : (a)

BAP also called 6-benzylaminopurine is soluble in Soluble in water, is a synthetic cytokinin that stimulates cell division in plants. Among other actions, it spurs plant growth, sets blossoms, and improves fruit quality. Cytokinins are in the plant growth hormone family MAP is poorly water soluble , is an activator of protein kinase Answer : (b)

The cohesion-tension theory is a theory of intermolecular attraction that explains the process of water flow upwards (against the force of gravity) through the xylem of plants. It also allows plants to draw water from the root through the xylem to the leaf. Water is constantly lost through transpiration from the leaf pulsation theory. The theory believes that the innermost cortical cells of the root absorb water from the outer side and pump the same into xylem channels limitations of pulsation theory : Taller plants like Eucalyptus need higher pressure to raise the water up. While the value of root pressure ranges from 2-5 atmospheres, a pressure of about 20 atm. is required to raise the water to tops of tall trees Theory of Capillarity: Water similarly rises up in the walls of xylem channels due to adhesion. Cohesive force present amongst water molecules pulls the water upwards through the xylem channels limitations Capillarity theory: The collapse of the free surface will happen when flow rate exceeds the critical value and then the capillary pressure can no longer balance the pressure difference. Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves Limiitations of Root pressure theory: Root pressure can only provide a modest push. Hence root pressure does not play a major role in water movement in tall plants Answer : (a)

When concentration of water in both the side is same osmosis stops When a sugar is added to beaker concentration of water in solution decreases, thus water will flows in to the beaker, from thisel funnel Answer : (d)

Difference between Transpiration and Evaporation. It is a physiological process. Transpiration is the loss of water from the plant cells. Evaporation is the loss of water from the free surface. Answer : (b)

Pascal is unit of measurment of water potential osmotic pressure. Answer : (c)

Fine roots are the most permeable portion of a root system, and are thought to have the greatest ability to absorb water, particularly in herbaceous (i.e., non-woody) plants Answer : (d)

Osmotic pressure of a solution is more than that of pure solvent Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. Answer : (a)

Answer : (d)

Answer : (a)

excessive fertilizers increases the concentration of solute, thus water from cell flows out, called exosmosis , reluts in wilting Answer : (b)

Force generated by transpiration can create pressure to lift water upto 130 metres Answer : (b)

deplasmolysis is swelling of the cytoplasm of a plasmolyzed cell. Water enters in cell from solution, thus solution is Hypotonic Answer : (a)

When the ambient temperature is high and soil contains excess water. the rate of transpiration is increased. Only 1% of water is lost through lenticels. Assertion is NOT correct Root pressure is caused by this accumulation of water in the xylem pushing on the rigid cells. Reason is NOT correct Answer : (d)

A potometer is a device used for measuring the rate of water uptake of a leafy plant shoot. The main reason for water uptake by a cut shoot is transpiration (evaporation in plants) and is affected by the transpiration stream. Answer : (b)

Surface tension is the tendency of fluid surfaces to shrink into the minimum surface area Answer : (c)

Imbibition is a special type of diffusion that takes place when water is absorbed by solids-colloids causing an increase in volume. Imbibition involves Movement of water into imbibant through diffusion as well as capillary action Answer : (c)

Stomata of CAM plants Open during night and close during the day Many cacti and other succulent plants with CAM metabolism open their stomata at night and close them during the day. CO2 is fixed into malate during the night because air temperatures are much lower at night than those of the day Answer : (c)

Transpiration ratios (TR) are low and on the order of 150 for CAM plants whereas for C4-plants it is on average 300 and C3-plants it is on average avearage 600 . Answer : (a)

When a solution is enclosed by a rigid cell wall, the movement of water into the cell will exert pressure on the cell wall. This increase in pressure within the cell will raise the water potential. Adding solute lowers the water potential. Answer : (c)

If cohesion-tension transpiration pull theory is correct, a break in water column would not provide suffiicient water, but transpiration will continue, inadequate water supply. There will be a loss of turgidity of leaves. This will result in the drooping, rolling and folding of leaves Answer : (c)

Abscisic acid (ABA), synthesized in response to drought stress, is known to induce stomatal closure and to reduce transpirational water loss Answer : (d)

Water from mango dipped in concentrated NaCl solution will come out reults in contraction Answer : (b)

Solutes reduce water potential (resulting in a negative Ψw) by consuming some of the potential energy available in the water. Answer : (c)

Guttation occurs in well watered herbaceous plants of well drained soils during morning Answer : (b)

The cell becomes turgid in solution which is Hypotonic Answer : (c)