Rate of transpiration is highest when (JKCMEE)

1.Which one gives the most valid explanation for guard cell movements? (CHD. CET 2002, MPPMT 91)
(a) Guard cell photosynthesis
(b) Starch hydrolysis theory
(c) Potassium influx and efflux
(d) Transpiration
Answer: (c)

2.Rate of transpiration is highest when (JKCMEE)
(a) soil is wet and air is dry
(b) soil is wet and air is humid
(c) soil is dry and air is humid
(d) both soil and air are dry
Answer: (a)

3.Which wall of the guard cells is thick? (CPMT 86, MPPMT 88)
(a) Lateral
(b) Inner
(c) Outer
(d) All of the above
Answer: (b)

4.Who said that ‘transpiration is a necessary evil”? (MP-PMT)
(a) Bose
(b) Steward
(c) Anderson
(d) Curtis
Answer: (d)

5.In order to demonstrate root pressure, the plant is given a cut (Har. PMT)
(a) at the tip
(b) transition zone
(c) a few centimeters above the soil
(d) a few centimeters below the soil
Answer: (c)

6.Cell membrane is ________.
(a) permeable
(b) impermeable
(c) semipermeable
(d) selectively permeable
Answer: (c)

7.Transpiration occurs from (CPMT 1980 & 1988, JIPMER 1988)
(a) leaves
(b) stem
(c) all aerial parts
(d) roots
Answer: (c)

8.Transpiration differs from evaporation in (CPMT 85)
(a) rate of water loss
(b) transpiration is a physiological process while evaporation is a physical process
(c) transpiration is a physical process while evaporation is a physiological process
(d) frequency of water loss
Answer: (b)

9.Cohesion theory of ascent of sap was proposed by (HP-PMT, BIHAR-PMT, R-PMT, AFMC))
(a) Munch
(b) Stephen Hales
(c) Dixon and Joly
(d) Bose
Answer: (c)

10.Which of the following explain ascent of sap?
(a) Cohesion theory
(b) Mass flow
(c) Diffusion
(d) Guttation
Answer: (a)

11.A semipermeable membrane allows the diffusion of (CPMT 1991)
(a) solutes
(b) Solvent
(c) Both solvent and solutes
(d) none of the above
Answer: (b)

12.Transpiration rate is dependent upon (CPMT 85)
(a) Stomatal frequency
(b) Position of stomata
(c) State of stomata
(d) All the above
Answer: (d)

13.In seed germination, the first to occur is (K-CET, BIH-MMT)
(a) Diffusion
(b) Exosmosis
(c) Endosmosis
(d) Imbibition
Answer: (d)

14.Transpiration is not helpful in ________.
(a) cooling
(b) Loss of nutrient
(c) Loss of water
(d) Ascent of sap
Answer: (b)

15.Root hairs absorb water from soil when (AFMC 1988, JIPMER 1986, CPMT 1984)
(a) osmotic concentration is same in the two
(b) solute concentration is higher in soil solution
(c) solute concentration is higher in root hairs
(d) absorption is active
Answer: (C)

16.Transpiration is regulated by movements of (JIPMER 2004, CPMT)
(a) guard cells
(b) subsidiary cells
(c) epidermal cells
(d) mesophyll cells
Answer: (a)

17.Exudation of xylem sap on cutting of a shoot is due to (R-PMT)
(a) guttation
(b) root pressure
(c) transpiration
(d) none of the above
Answer: (a)

18.Rate of transpiration increases ________.
(a) when there is no light
(b) in water
(c) when temperature is high
(d) in rainy season
Answer: (c)

19.Raisins placed in water swell up due to (CPMT 1988)
(a) plasmolysis
(b) adsorption
(c) diffusion
(d) endosmosis
Answer: (d)

20.Transpiration is least in (KCET 2006, BHU DPMT, CBSE)
(a) Good soil moisture
(b) High wind velocity
(c) Dry environment
(d) High atmospheric humidity
Answer: (d)