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Quiz 9
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Q.1
Which one does not involve osmosis ... ... [ MPPMT 1991]
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a) Water passing from one xylem element to the other above it
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b) Water passing from soil to root hair
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c) Water passing into mesophyll cell from xylem
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d) Water passing from root hair cell to cortical cell
Explanation
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)
Q.2
Cohesion force existing amongst water molecules contributes to.. ...[ KCET 2002]
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a) Plasmolysis
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b) Ascent of sap
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c) Osmosis
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d) Translocation
Explanation
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)
Q.3
Assertion: Stomata remain open during day time Reason: Stomata help in exchange of gases ... ..... [ AIIMS 2001]
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a) If both the assertion and reason are true and reason explains the assertion.
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b) If both the assertion and reason are true but reason does not explain the assertion
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c) If assertion is true but reason is false
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d) If assertion is false but reason is true.
Explanation
Answer : (b)
Q.4
Graham's law is connected with ... ...[ W.B. 2009]
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a) Diffusion
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b) Osmosis
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c) Osmoregulation
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d) Absorption
Explanation
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)
Q.5
The force responsible for raising water in 100ft tall plant is ... ....[ Odisha 2011]
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a) Transpiration pull
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b) Root pressure
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c) Air pressure
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d) Capillary action
Explanation
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)
Q.6
Which is not an antitranspirants ... ... [ KCET 2011]
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a) Low viscosity resin
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b) BAP
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c) Silicon oil
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d) PMA
Explanation
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)
Q.7
Upward movement of water through xylem is best explained by ... ...
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a) Cohesion theory
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b) Pulsation theory
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c) Capillarity theory
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d) Root pressure theory
Explanation
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)
Q.8
In thistle funnel experiment what will happen if sugar is added to beaker after the stoppage of osmosis ... ... [ Guj CET 2008]
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a) Level of solution in beaker lowers
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b) Level of solution in thistle funnel rises up
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c) Level of solution remains unaffected in beaker
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d) Level of solution in thistle funnel lowers
Explanation
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)
Q.9
Transpiration differs from evaporation in ... ... [ CPMT 1992]
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a) Rate of water loss
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b) Transpiration is physiological process while evaporation is a physical process
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c) Transpiration is physical process while evaporation is physiological process
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d) Frequency of water loss
Explanation
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)
Q.10
Which one is a unit of measurement of water potential/osmotic pressure? ... ..... [ Manipur 2007]
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a) Watts
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b) Joule
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c) Pascal
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d) Litre
Explanation
Pascal is unit of measurment of water potential osmotic pressure. Answer : (c)
Q.11
The maximum absorption of water by roots occurs in the (region) zone of ... ..... [ MPPMT 2001]
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a) Root cap
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b) Cell division
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c) Cell elongation
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d) Root hairs
Explanation
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)
Q.12
Osmotic pressure of a solution is ... ..[ DPMT 2003]
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a) More than that of pure solvent
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b) Less than that of pure solvent
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c) Variable depending upon concentration
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d) Equal to that of pure solvent
Explanation
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)
Q.13
A sudden increase in carbon dioxide concentration around a leaf will cause .... ...[ AFMC 2001]
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a) Wide opening of stomata
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b) Increase in transpiration
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c) Closure of stomata
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d) Decrease in transpiration due to closure of stomata
Explanation
Answer : (d)
Q.14
Statement a: To counteract the increase in turgor pressure in plant cells the cell wall produces an equal and opposite pressure i.e. wall pressure Statement b: When plant cells undergo endosmosis, they swell but do not burst
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a) Both the statement a and b are correct and a is reason for b
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b) Statement a is correct and b is wrong
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c) Statement a is wrong and b is correct
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d) Both the statements a and b are correct and a is not the reason for b
Explanation
Answer : (a)
Q.15
Use of excessive fertilizers causes wilting due to .... .... [ Kerala 2002]
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a) Endosmosis
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b) Exosmosis
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c) Imbibition
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d) None of the above
Explanation
excessive fertilizers increases the concentration of solute, thus water from cell flows out, called exosmosis , reluts in wilting Answer : (b)
Q.16
Force generated by transpiration can create pressure to lift water upto ... .... [ AMU 2012]
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a) 130 feet
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b) 130 metres
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c) 230 feet
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d) 230 metres
Explanation
Force generated by transpiration can create pressure to lift water upto 130 metres Answer : (b)
Q.17
A cell placed in a solution get deplasmolysed. The solution is ... ...[ CPMT 1996]
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a) Hypotonic
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b) Hertonic
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c) Isotonic
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d) Ditonic
Explanation
deplasmolysis is swelling of the cytoplasm of a plasmolyzed cell. Water enters in cell from solution, thus solution is Hypotonic Answer : (a)
Q.18
Assertion: When the ambient temperature is high and the soil contains excess of water the plants tends to loss water in the form of droplets from lenticels Reason: Root pressure regulates the rate of loss of water from lenticels ... .... [ AIIMS 2006]
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a) If both the assertion and reason are true and reason explains the assertion
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b) If both the assertion and reason are true but reason does not explain the assertion.
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c) If assertion is true but reason is false
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d) If both are wrong
Explanation
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)
Q.19
Potometer is an instrument that measures ... ... [ Pb PMT 1998]
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a) Respiration
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b) Transpiration
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c) Growth
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d) Photosynthesis
Explanation
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)
Q.20
Which one does not help in ion or molecular transport? ... .... [ JIPMER 2004]
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a) Diffusion
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b) Osmosis
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c) Surface tension
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d) Active transport
Explanation
Surface tension is the tendency of fluid surfaces to shrink into the minimum surface area Answer : (c)
Q.21
Imbibition involves ... .... [ CPMT 1990]
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a) Diffusion of water
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b) Movement of water into imbibant through capillarity
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c) Movement of water into imbibant through diffusion as well as capillary action
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d) Adsorption of water
Explanation
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)
Q.22
Stomata of CAM plants ... ...[ CBSE 2003]
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a) Are always open
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b) Open during the day and close at night
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c) Open during night and close during the day
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d) Never open
Explanation
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)
Q.23
Rate of transpiration is high in ... .... [ MPPMT 2001]
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a) C3 plants
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b) C4 plants
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c) CAM plants
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d) Both C3 and C4 plants
Explanation
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)
Q.24
Water potential increases due to ......[ CET Chd.2009]
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a) Evaporation
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b) Addition of solutes
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c) Pressure
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d) Afforestation
Explanation
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)
Q.25
If cohesion-tension transpiration pull theory is correct, a break in water column should .... ..[ AIIMS 1997]
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a) Increase water content of leaves
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b) Increase rate of photosynthesis
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c) Cause wilting of leaves
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d) Have no effect at all
Explanation
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)
Q.26
Accumulation of which one of the following acids results in closure of stomata ... ... [ AMU 2011]
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a) Malic acid
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b) Aspartic acid
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c) PEP
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d) Abscisic acid
Explanation
Abscisic acid (ABA), synthesized in response to drought stress, is known to induce stomatal closure and to reduce transpirational water loss Answer : (d)
Q.27
Mango dipped in concentrated NaCl solution will ... ...[ CPMT 1995]
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a) Burst
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b) Contract
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c) Swell
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d) No effect
Explanation
Water from mango dipped in concentrated NaCl solution will come out reults in contraction Answer : (b)
Q.28
Select the correct one ..... ... [ kerela 2007] a) apoplast movement of water occurs exclusively through cell wall b) Solutes increases free energy of water or water potential c) symplast movement occurs through plasmodesmata d) Membrane permeability depends upon membrane composition as well as chemical nature of solute
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a) a and b only
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b) b and d only
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c) a, c and d only
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d) a, b and d only
Explanation
Solutes reduce water potential (resulting in a negative Ψw) by consuming some of the potential energy available in the water. Answer : (c)
Q.29
Guttation occurs in well watered herbaceous plants of well drained soils during ... .. [ RPMT 1995]
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a) Evening
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b) Morning
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c) Day
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d) Noon
Explanation
Guttation occurs in well watered herbaceous plants of well drained soils during morning Answer : (b)
Q.30
The cell becomes turgid in solution which is ... .... [ RPMT 2005]
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a) Hypertonic
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b) Isotonic
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c) Hypotonic
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d) None of the above
Explanation
The cell becomes turgid in solution which is Hypotonic Answer : (c)
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