PLANT - WATER RELATIONS

1. Dry seeds when placed in, water swells up due to:
(a) Osmosis (b) hydrolysis
(c) reverse osmosis (d) imbibition
2. Which one of the following formed during water stress causes the closure of stomata ?
(a) auxin
(c) cytokinin
3. Water potential of pure water is (a) Zero bar
(c) 10 bar
(b) abscisic acid (d) gibberellin
(b) 100 bar (d) 1 bar
4. Water potential ofs leaf tissue will be more negative during.
(a) low transpiration (c) less respiration (b) high transpiration
(d) excessive transpiration
5. Stomata of angiosperms usually do not open during.
(a) moonlight (c) mid night (b) mid day
(d) Hot day
6. In a dry cool day, the rate of tranptration will be:
(a) low
(c) no transpiration
7. Salted mangoes shrink due to : (a) exosmosis
(c) endosmosis
(b) high
(d) minimum
(b) plasmolysis (d)'imbibition

Cohesion theory-of ascent of sap is put for ward by:
(a) Henry. Dixon (b) Melvin Calvin
(c) Dixion and Joley (d) Curtis
10. The chief organ otwater absorption,is :
(a) root cap (b) entire root surface
(c) root hairs (d) root apex
Plants do not absorb water from the soil when - (ar there is less soil CO2
(b) soil temperature below 38° C
(c) there is high solute concentration
(d) atmospheric "temperature above 38 ° C
12. CAM plants could open their stomata during :
(a) day only (b) night only
.(c) even in twilight (d) even in midday
13. D.P.D is equal to : (a) 0.P - W.P (b) 0.P + W.P (c) T.P (d) 0.P
14. The principal pathWay of water transloCation in angiosperms is :
(a) sieve cells (b) sieve tube elements
(c) xylem vessel elements- (d) -xylem and 'phloem
The osmotic movement of water may be prevented by applying a pressure namely :
(a) root pressure (b) wall pressure (d) turgor pressure
(c) osmotic pressure
16. The water which js readily available to plants for absorption by roots is called.
(a) hygroscopic water (b) capillary water (c),atomospheric water (d) gravitational water
17. Guttation occurs through specialised pores called:
(a) stomata (b) lenticels
(c) hydathodes (d) air pores