Transport system in plant Top 100 MCQs With Answer and Explanation

1. The movement of molecules from a region of higher concentration to lower concentration is called ____________.
A) Osmosis
B) Diffusion
C) Active transport
D) Imbibition

2. The movement of water through a semi-permeable membrane is called ____________.
A) Diffusion
B) Osmosis
C) Imbibition
D) Transpiration

3. Imbibition is important in ____________.
A) Root elongation
B) Seed germination
C) Photosynthesis
D) Transpiration

4. A solution with lower solute concentration compared to another is called ____________.
A) Isotonic
B) Hypotonic
C) Hypertonic
D) None of these

5. Plasmolysis occurs when a cell is placed in ____________.
A) Hypotonic solution
B) Isotonic solution
C) Hypertonic solution
D) Distilled water

6. The pressure responsible for water absorption in roots is ____________.
A) Root pressure
B) Osmotic pressure
C) Turgor pressure
D) Diffusion pressure

7. Which instrument is used to study plasmolysis?
A) Simple microscope
B) Compound microscope
C) Electron microscope
D) X-ray diffraction

8. When the cell wall resists further entry of water, the cell is said to be ____________.
A) Flaccid
B) Turgid
C) Plasmolysed
D) Hypertonic

9. Water potential of pure water is ____________.
A) 1
B) 0
C) –1
D) 100

10. Active transport in plants requires ____________.
A) ATP energy
B) Osmosis
C) Diffusion
D) Imbibition

11. Symplastic movement of water occurs through ____________.
A) Cell wall
B) Cytoplasm via plasmodesmata
C) Vacuole only
D) Xylem vessels only

12. Apoplastic movement of water occurs through ____________.
A) Vacuoles
B) Cytoplasm
C) Cell walls and intercellular spaces
D) Plasmodesmata

13. The symplastic pathway is interrupted by ____________.
A) Xylem
B) Phloem
C) Casparian strips
D) Pith

14. The first step in water absorption by roots is ____________.
A) Diffusion
B) Active transport
C) Osmosis
D) Imbibition

15. The term water potential was introduced by ____________.
A) van’t Hoff
B) Slatyer & Taylor
C) Dixon & Joly
D) Strasburger

16. When a cell is in isotonic solution, its water potential is ____________.
A) Higher than outside
B) Lower than outside
C) Equal to outside
D) Zero

17. Root pressure is maximum in ____________.
A) Dry season
B) Early spring
C) Rainy season
D) Midday summer

18. The swelling of wooden doors in rainy season is due to ____________.
A) Osmosis
B) Imbibition
C) Diffusion
D) Capillarity

19. The units of water potential are ____________.
A) Calories
B) Joules
C) Pascal (pressure units)
D) Litres

20. The diffusion pressure deficit (DPD) is equivalent to ____________.
A) Osmotic pressure – Turgor pressure
B) Osmotic pressure + Turgor pressure
C) Osmotic pressure – Wall pressure
D) Water potential × Turgor pressure

21. The entry of water into guard cells causing stomatal opening is due to ____________.
A) Active transport of K⁺
B) Passive diffusion of CO₂
C) Plasmolysis
D) Protein synthesis

22. Endosmosis occurs when a cell is placed in ____________.
A) Hypotonic solution
B) Hypertonic solution
C) Isotonic solution
D) None of these

23. Exosmosis occurs when a cell is placed in ____________.
A) Hypotonic solution
B) Hypertonic solution
C) Isotonic solution
D) Distilled water

24. The movement of water from soil into xylem across cortex is mainly ____________.
A) Apoplastic & Symplastic
B) Only active
C) Only through vacuoles
D) By guttation

25. In higher plants, water mainly moves upward through ____________.
A) Phloem
B) Xylem
C) Cortex
D) Cambium

26. The main region of water absorption in roots is ____________.
A) Root cap
B) Meristematic zone
C) Zone of root hairs
D) Zone of elongation

27. Water absorption by roots is mostly ____________.
A) Passive
B) Active
C) Imbibition
D) Endosmosis

28. Root pressure is best demonstrated by ____________.
A) Plasmolysis experiment
B) Guttation
C) Transpiration
D) Phototropism

29. The ascent of sap in tall trees is best explained by ____________.
A) Root pressure theory
B) Capillarity theory
C) Cohesion-tension theory
D) Imbibition theory

30. Capillary theory is insufficient to explain ascent of sap because ____________.
A) Water is not cohesive
B) Trees are tall (up to 100 m)
C) Root pressure is absent
D) It requires ATP

31. The cohesion-tension theory was proposed by ____________.
A) Strasburger
B) Dixon & Joly
C) Bose
D) Priestley

32. Maximum transpiration occurs through ____________.
A) Lenticels
B) Cuticle
C) Stomata
D) Hydathodes

33. The cuticular transpiration is minimum in ____________.
A) Xerophytes
B) Hydrophytes
C) Mesophytes
D) Halophytes

34. The loss of water in liquid form through hydathodes is called ____________.
A) Transpiration
B) Guttation
C) Exudation
D) Dew

35. Stomata open due to ____________.
A) Loss of turgor in guard cells
B) Gain of turgor in guard cells
C) Photosynthesis in spongy cells
D) Root pressure

36. Which factor closes stomata?
A) Blue light
B) Absorption of K⁺ by guard cells
C) Abscisic acid (ABA)
D) Photosynthesis

37. The driving force of transpiration pull is ____________.
A) Root pressure
B) Water potential gradient
C) Guttation
D) Osmosis

38. The first step of transpiration is ____________.
A) Movement into xylem
B) Evaporation from mesophyll cells into intercellular spaces
C) Diffusion out through stomata
D) Root pressure

39. The transpiration ratio is ____________.
A) CO₂ fixed / water lost
B) Water lost / CO₂ fixed
C) O₂ released / water lost
D) Water absorbed / water transpired

40. Transpiration is measured by ____________.
A) Potometer
B) Hygrometer
C) Psychrometer
D) Porometer

41. The least transpiration occurs in ____________.
A) Xerophytes
B) Hydrophytes
C) Mesophytes
D) Halophytes

42. The phenomenon of guttation occurs mainly at ____________.
A) Stomata
B) Lenticels
C) Hydathodes
D) Cuticle

43. Which plant will show maximum transpiration rate?
A) Cactus
B) Mango
C) Lotus
D) Water hyacinth

44. During midday in summer, the rate of transpiration ____________.
A) Increases continuously
B) Decreases due to stomatal closure
C) Remains constant
D) Stops completely

45. Transpiration helps in ____________.
A) Cooling leaves
B) Ascent of sap
C) Distribution of minerals
D) All of these

46. Antitranspirants reduce transpiration by ____________.
A) Increasing photosynthesis
B) Inducing stomatal closure
C) Increasing root pressure
D) Breaking hydrogen bonds

47. Water is pulled upward in xylem mainly due to ____________.
A) Root pressure
B) Cohesion and adhesion of water
C) Imbibition
D) Capillarity alone

48. Which plant shows Crassulacean Acid Metabolism (CAM) to reduce transpiration?
A) Rice
B) Wheat
C) Opuntia
D) Mango

49. Xerophytes conserve water by ____________.
A) Thick cuticle
B) Sunken stomata
C) Reduced leaf area
D) All of these

50. The ascent of sap stops when ____________.
A) Root pressure is low
B) Cohesion of water is lost (air embolism)
C) Temperature is high
D) Cuticle is thick

51. The main conducting tissue for mineral nutrients in plants is ____________.
A) Phloem
B) Xylem
C) Cortex
D) Cambium

52. Essential elements are those which ____________.
A) Are required in large amounts only
B) Cannot be replaced by other elements
C) May or may not be required for metabolism
D) Are required only in hydroponics

53. Hydroponics is a technique used to ____________.
A) Study root nodules
B) Grow plants without soil
C) Prevent transpiration
D) Increase guttation

54. Which mineral is part of chlorophyll?
A) Calcium
B) Magnesium
C) Iron
D) Sulphur

55. Which mineral is essential for nitrogen fixation in legumes?
A) Boron
B) Iron & Molybdenum
C) Potassium
D) Calcium

56. Necrosis (death of tissues) is mainly due to deficiency of ____________.
A) K, Ca, Mg
B) Fe, Mn, Zn
C) Mo, B
D) Na, Cl

57. Chlorosis (yellowing of leaves) is caused by deficiency of ____________.
A) N, K, Mg, Fe, S, Mo
B) Ca, B, Mn
C) Na, Cl, Zn
D) P, Cu, Mn

58. Which mineral is needed for photolysis of water during photosynthesis?
A) Fe
B) Mn
C) Mg
D) Ca

59. Which mineral is most immobile in plants?
A) Nitrogen
B) Phosphorus
C) Calcium
D) Potassium

60. Which mineral is required for synthesis of auxin (IAA)?
A) Fe
B) Zn
C) Cu
D) Mg

61. The main tissue for transport of organic food in plants is ____________.
A) Xylem
B) Phloem
C) Cambium
D) Endodermis

62. Food is transported in phloem mainly in the form of ____________.
A) Glucose
B) Fructose
C) Sucrose
D) Starch

63. In phloem, which cells are responsible for transport?
A) Companion cells & sieve tube elements
B) Tracheids & vessels
C) Phloem parenchyma
D) Cambium cells

64. The direction of food transport in phloem is ____________.
A) Only upward
B) Only downward
C) Both upward and downward
D) Random

65. The pressure-flow hypothesis was proposed by ____________.
A) Dixon & Joly
B) Münch
C) Strasburger
D) Priestley

66. According to pressure-flow hypothesis, transport in phloem occurs due to ____________.
A) Root pressure
B) Turgor pressure gradient
C) ATP energy only
D) Cohesion-tension

67. In phloem loading, sugars move from mesophyll cells into sieve tubes by ____________.
A) Passive diffusion
B) Active transport
C) Osmosis
D) Capillarity

68. In pressure-flow mechanism, “source” refers to ____________.
A) Organs where food is utilized
B) Organs where food is stored
C) Organs where food is synthesized
D) Root apex

69. In pressure-flow mechanism, “sink” refers to ____________.
A) Leaves
B) Roots, fruits, seeds
C) Xylem
D) Cambium

70. Phloem transport is ____________.
A) Apoplastic
B) Symplastic
C) Both apoplastic and symplastic
D) Vacuolar only

71. Translocation of food in phloem requires ____________.
A) Light
B) ATP
C) Oxygen
D) Both B and C

72. The translocation rate in phloem is ____________.
A) 1 mm/hour
B) 1 m/hour
C) 1 cm/day
D) 0.1 mm/day

73. The girdling experiment (removal of phloem) shows that ____________.
A) Water transport occurs in phloem
B) Food transport occurs in phloem
C) Minerals move in cortex
D) Transpiration pull occurs in phloem

74. The sieve plates in phloem are present in ____________.
A) Sieve tube elements
B) Companion cells
C) Xylem tracheids
D) Phloem parenchyma

75. The energy for phloem transport comes from ____________.
A) Photosynthesis directly
B) Active loading by companion cells
C) Transpiration pull
D) Root pressure

76. The cohesion-tension theory of water transport explains ____________.
A) Phloem transport
B) Ascent of sap in xylem
C) Mineral nutrition
D) Osmosis in root hairs

77. Root pressure alone cannot account for water rise in tall trees because ____________.
A) It is too weak
B) It occurs only at night
C) It is absent in dry soil
D) All of these

78. Which condition favours guttation?
A) Low root pressure, high transpiration
B) High root pressure, low transpiration
C) High transpiration, high temperature
D) None of these

79. Transpiration pull is strongest in ____________.
A) Midday
B) Midnight
C) Early morning
D) Evening

80. Which experiment proves that food is translocated through phloem?
A) Plasmolysis experiment
B) Girdling experiment
C) Potometer experiment
D) Bell jar experiment

81. Food translocation in plants is always ____________.
A) From root to shoot
B) From leaves to roots only
C) From source to sink
D) Random

82. The rate of translocation in phloem is approximately ____________.
A) 1 cm/hr
B) 1 m/hr
C) 1 cm/day
D) 1 mm/hr

83. Which plant shows CAM photosynthesis to conserve water?
A) Wheat
B) Rice
C) Opuntia
D) Mango

84. The transpiration-cohesion theory fails if ____________.
A) Water molecules lose cohesion (embolism)
B) Transpiration rate decreases
C) Light intensity is low
D) Root pressure develops

85. In hydrophytes, cuticle and transpiration are ____________.
A) Thick and high
B) Absent and negligible
C) Thick and negligible
D) Thin and high

86. Xerophytes minimize water loss by ____________.
A) Thick cuticle
B) Sunken stomata
C) Reduced leaves (spines)
D) All of these

87. The movement of sugars from mesophyll cells to phloem is called ____________.
A) Phloem loading
B) Phloem unloading
C) Transpiration pull
D) Mineral transport

88. Water absorption through mycorrhizal association is most important for ____________.
A) Nitrogen
B) Potassium
C) Phosphorus
D) Calcium

89. Which ion plays a major role in stomatal movement?
A) Na⁺
B) K⁺
C) Ca²⁺
D) Mg²⁺

90. During drought stress, stomata close due to ____________.
A) Auxin
B) Abscisic acid (ABA)
C) Cytokinin
D) Ethylene

91. In phloem, the living cells that assist sieve tubes are ____________.
A) Phloem fibres
B) Phloem parenchyma
C) Companion cells
D) Cambium cells

92. In tall trees, ascent of sap occurs mainly due to ____________.
A) Root pressure
B) Transpiration pull
C) Capillarity
D) Osmosis

93. Which plant factor reduces transpiration?
A) Large leaf area
B) Sunken stomata
C) Thin cuticle
D) High stomatal frequency

94. In girdling experiment, food accumulates ____________.
A) Below the girdle
B) Above the girdle
C) Both above and below
D) At the root tip

95. Which factor reduces the rate of transpiration?
A) High temperature
B) Low humidity
C) High wind velocity
D) High atmospheric humidity

96. The process of guttation is mainly seen in ____________.
A) Tall trees
B) Herbs with large leaves
C) Succulents
D) Xerophytes

97. Active transport in phloem requires ____________.
A) ATP
B) Osmosis
C) Root pressure
D) Cohesion

98. The closing of stomata at night is mainly due to ____________.
A) CO₂ accumulation
B) Loss of turgor in guard cells
C) High transpiration rate
D) ABA action

99. Which statement is correct regarding translocation of food?
A) It occurs only in downward direction
B) It occurs only during the day
C) It occurs both upward and downward
D) It is independent of source and sink

100. Which is the most accepted theory of food transport in plants?
A) Diffusion theory
B) Protoplasmic streaming theory
C) Pressure-flow hypothesis
D) Electro-osmotic theory