Transpiration
Multiple Choice Questions and Answers
1. The metal ion involved in stomatal regulation is
(a) iron
(b) magnesium
(c) zinc
(d) potassium
Answer: (d) potassium
2. Increase in CO2 concentration around leaf causes
(a) rapid opening of stomata
(b) partial closure of stomata
(c) complete closure of stomata
(d) there will be no effect on stomatal opening
Answer: (c) complete closure of stomata
3. Transpiration occurs from
(a) leaves
(b) stems
(c) all aerial parts
(d) roots
Answer: (c) all aerial parts
4. What percentage of water absorbed by herbaceous plants is lost during transpiration?
(a) 80
(b) 60
(c) 90
(d) 40
Answer: (c) 90
5. Stomata open during the daytime because the guard cells
(a) photosynthesize and produce osmotically active sugars
(b) are thin walled
(c) are bean shaped
(d) have to help in gaseous exchange
Answer: (a) photosynthesize and produce osmotically active sugars
6. In which of the following plants would metabolism be hindered if the leaves are coated with wax on their upper surface
(a) Hydrilla
(b) Lotus
(c) Pistia
(d) Vallisneria
Answer: (b) Lotus
7. Active potassium ions exchange mechanism for opening and closing of stomata was given by
(a) Darwin
(b) Levitt
(c) Scarth
(d) Khorana
Answer: (b) Levitt
8. On a wind less hot day, one would perspire more in a thick forest because
(a) heat is created by respiration of plants
(b) plants transpire
(c) comparatively less light falls in the forest
(d) it is only a psychological reason
Answer: (b) plants transpire
9. Of the processes which occurs in leaves, the one which may lower their temperature is
(a) respiration
(b) photosynthesis
(c) transpiration
(d) hydrolysis
Answer: (c) transpiration
10. Which is the action spectrum of transpiration?
(a) green and ultraviolet
(b) orange and red
(c) blue and far red
(d) blue and red
Answer: (d) blue and red
11. Water of guttation is
(a) pure water
(b) water with dissolved salts
(c) solution of organic food
(d) condensed water vapour
Answer: (b) water with dissolved salts
12. The actual amount of moisture retained by the air is called
(a) absolute humidity
(b) positive humidity
(c) relative humidity
(d) differential humidity
Answer: (c) relative humidity
13. The conditions under which transpiration would be most rapid
(a) high humidity
(b) excess of water in the soil
(c) low humidity and high temperature
(d) low wind velocity
Answer: (c) low humidity and high temperature
14. If the stomata more on the under surface of the leaves than on upper, it comes under
(a) Oat type
(b) Barley type
(c) Potato type
(d) Potamogeton type
Answer: (c) Potato type
15. Which of the following is used to determine the rate of transpiration in plants?
(a) porometer
(b) potometer
(c) auxanometer
(d) photometer
Answer: (b) potometer
16. Wilting of plants result from excessive
(a) respiration
(b) photosynthesis
(c) absorption
(d) transpiration
Answer: (d) transpiration
17. In many thin leaved mesophytes, stomata open during day and close at night. This comes under
(a) Barley type
(b) Potato type
(c) Alphalpha type
(d) Bean type
Answer: (c) Alphalpha type
18. Generally, the number of stomata per square centimetre leaf area is
(a) in millions
(b) less than 100
(c) in thousands
(d) none of the above
Answer: (c) in thousands
19. The plants die due to wilting when
(a) available light is reduced to half
(b) xylem is blocked
(c) a few roots are broken
(d) phloem is blocked
Answer: (b) xylem is blocked
20. Conversion of starch to organic acid is essential for stomatal
(a) closure
(b) opening
(c) initiation
(d) growth
Answer: (b) opening
21. The process of the escape of liquid from the tip of injured leaf is called
(a) evaporation
(b) transpiration
(c) guttation
(d) evapo-transpiration
Answer: (c) guttation
22. Which of the following is produced during water stress and causes closure of stomata?
(a) cytokinin
(b) auxin
(c) GA3
(d) ABA
Answer: (d) ABA
23. Phenyl mercuric acetate
(a) reduces transpiration
(b) reduces photosynthesis
(c) decreases water absorption
(d) kills the plant
Answer: (a) reduces transpiration
24. The rate of transpiration is dependent upon
(a) negative root pressure
(b) temperature
(c) DPD
(d) vapour pressure deficit
Answer: (d) vapour pressure deficit
25. A specialised multicellular structure in leaves which excretes water droplets is
(a) lenticels
(b) stomata
(c) hydathode
(d) bordered pit
Answer: (c) hydathode
26. Increase in the CO2 concentration of micro environment of leaf would cause
(a) closure of stomata
(b) opening of stomata
(c) no effect on stomata
(d) wider opening of stomata
Answer: (a) closure of stomata
27. Process of water exudation through hydathodes is called
(a) guttation
(b) transpiration
(c) excretion
(d) hydrolysis
Answer: (a) guttation
28. Which one of the following factors is the most important the regulation of transpiration?
(a) humidity
(b) light
(c) temperature
(d) wind
Answer: (a) humidity
29. In old trees or woody plants transpiration occurs through
(a) stomata
(b) bark
(c) lenticels
(d) root
Answer: (c) lenticels
30. In the process of transpiration the water from ground to the root moves due to
(a) osmosis
(b) imbibition
(c) transpiration pull
(d) plasmolysis
Answer: (a) osmosis
31. In a hot sunny day water in plants is
(a) pushed up
(b) pulled up
(c) sucked up
(d) all of the above
Answer: (b) pulled up
32. Mid-day closure of stomata is due to
(a) maximum rate of photosynthesis
(b) fatigue
(c) high wind velocity
(d) excessive transpiration
Answer: (d) excessive transpiration
33. Stomata are widespread in plant Kingdom accept
(a) algae and fungi
(b) angiosperms and gymnosperms
(c) cycads and ferns
(d) horse tails and mosses
Answer: (a) algae and fungi
34. What is the action spectrum of transpiration?
(a) orange and red
(b) blue and red
(c) green and UV
(d) blue and far red
Answer: (b) blue and red
35. Basis of stomatal opening is
(a) decrease in cell sap concentration
(b) plasma lies of guard cells
(c) endosmosis
(d) exosmosis
Answer: (c) endosmosis
36. The stomatal transpiration almost completely stops at
(a) night
(b) noon
(c) in the morning
(d) in the evening
Answer: (a) night
37. The magnitude of water loss as a result of transpiration will be greater when
(a) leaf area is greater
(b) there is increase in temperature
(c) there is increase in wind velocity
(d) all of the above
Answer: (d) all of the above
38. The cause of guttation is
(a) transpiration
(b) higher leaf temperature
(c) higher root pressure
(d) obstructed xylem elements
Answer: (c) higher root pressure
39. Stomata can open at night also in
(a) xerophytes
(b) gametophytes
(c) hydrophytes
(d) none of these
Answer: (a) xerophytes
40. Who had said that ‘transpiration is a necessary evil’?
(a) Curtis
(b) Steward
(c) Anderson
(d) J C Bose
Answer: (a) Curtis
41. Wilting of plants occurs due to
(a) root pressure
(b) transpiration
(c) guttation
(d) DPD
Answer: (b) transpiration
42. Which of the following helps in opening of stomata?
(a) potassium ions
(b) calcium ions
(c) hydrogen ions
(d) chloride ions
Answer: (a) potassium ions
43. Guttation occurs when plants absorb water by
(a) active absorption
(b) passive absorption
(c) root pressure
(d) both a and b
Answer: (c) root pressure
44. The internal factor for transpiration is
(a) oxygen
(b) carbon dioxide
(c) nitrogen
(d) sunken stomata
Answer: (d) sunken stomata
45. Stomata of a plant open due to
(a) influx of potassium ions
(b) efflux of potassium ions
(c) influx of hydrogen ions
(d) influx of calcium ions
Answer: (a) influx of potassium ions
46. What does not cause stomatal opening?
(a) circadian rhythm
(b) influx of potassium ions
(c) light
(d) high carbon dioxide concentration
Answer: (d) high carbon dioxide concentration
47. Transpiration is mainly a process of
(a) imbibition
(b) respiration
(c) osmotic pressure
(d) diffusion
Answer: (d) diffusion
48. Which ones did not show transpiration?
(a) aquatic plants with floating leaves
(b) aquatic submerged plants
(c) plants growing in hilly areas
(d) plants living in desert
Answer: (b) aquatic submerged plants
49. Oozing out of water drops from injured edges or tips is
(a) bleeding
(b) guttation
(c) transpiration
(d) oozation
Answer: (a) bleeding
50. Conversion of starch to ……. is essential for stomatal regulation
(a) protein
(b) organic acid
(c) fat
(d) alcohol
Answer: (b) organic acid