🌱 Transport in Plants – MCQs

Part 1 (Q1–Q25)

Q1. The main solvent in plant transport is

A) Alcohol
B) Water ✅
C) Glucose
D) Amino acids

Explanation: Water is the universal solvent; transport of minerals, sugars, and hormones depends on it.

Q2. The process of diffusion requires

A) ATP
B) Carrier proteins
C) Concentration gradient ✅
D) Light

Explanation: Diffusion is passive, driven by concentration gradient, no ATP required.

Q3. The net movement of molecules is from

A) Higher to lower concentration ✅
B) Lower to higher concentration
C) Equal to equal concentration
D) Random

Explanation: Diffusion occurs down the concentration gradient.

Q4. The diffusion of water across a semipermeable membrane is called

A) Filtration
B) Osmosis ✅
C) Imbibition
D) Transpiration

Explanation: Osmosis = passive movement of water across a semipermeable membrane.

Q5. Which solution has higher water potential?

A) Pure water ✅
B) Sugar solution
C) Salt solution
D) Acidic solution

Explanation: Pure water has maximum water potential (Ψ = 0).

Q6. The pressure exerted by plasma membrane against the cell wall is

A) Wall pressure
B) Turgor pressure ✅
C) Diffusion pressure
D) Osmotic pressure

Explanation: Turgor pressure maintains rigidity of plant cells.

Q7. Loss of water through cuticle is

A) Guttation
B) Cuticular transpiration ✅
C) Lenticular transpiration
D) Stomatal transpiration

Explanation: Cuticular transpiration occurs through waxy cuticle (minor compared to stomatal).

Q8. The major pathway of water loss in plants is

A) Lenticular transpiration
B) Stomatal transpiration ✅
C) Cuticular transpiration
D) Guttation

Explanation: Stomatal transpiration accounts for 90–95% of total water loss.

Q9. The loss of water as droplets from leaf margins is

A) Transpiration
B) Guttation ✅
C) Osmosis
D) Diffusion

Explanation: Guttation occurs through hydathodes due to root pressure.

Q10. The pressure generated in xylem due to active water absorption is

A) Root pressure ✅
B) Turgor pressure
C) Osmotic pressure
D) Capillary action

Explanation: Root pressure is positive hydrostatic pressure in xylem.

Q11. The main force for upward movement of water in tall trees is

A) Root pressure
B) Capillarity
C) Transpiration pull ✅
D) Osmosis

Explanation: Transpiration pull + cohesion-tension mechanism explains water ascent.

Q12. The Cohesion-tension theory was proposed by

A) Darwin
B) Dixon and Joly ✅
C) Münch
D) Haberlandt

Explanation: Dixon and Joly (1894) proposed the cohesion-tension theory.

Q13. The translocation of food in plants occurs through

A) Xylem
B) Phloem ✅
C) Cortex
D) Epidermis

Explanation: Phloem transports sucrose, amino acids, and hormones bidirectionally.

Q14. The Pressure-flow hypothesis was proposed by

A) Dixon and Joly
B) Münch ✅
C) Strasburger
D) Priestley

Explanation: Münch (1930) explained phloem transport as mass flow hypothesis.

Q15. Xylem transports

A) Water and minerals ✅
B) Sugars only
C) Amino acids
D) Hormones

Explanation: Xylem transports water + minerals unidirectionally.

Q16. Phloem transports

A) Water
B) Minerals
C) Organic food ✅
D) Ions only

Explanation: Phloem transports sucrose and other organic solutes both ways.

Q17. The main form of sugar translocated in phloem is

A) Glucose
B) Fructose
C) Sucrose ✅
D) Maltose

Explanation: Sucrose is the main transport sugar in plants.

Q18. In translocation, loading of sucrose occurs in

A) Source cells ✅
B) Sink cells
C) Root hairs
D) Hydathodes

Explanation: Source cells (leaves) load sucrose into phloem actively.

Q19. The apoplast pathway involves

A) Cytoplasm
B) Vacuole
C) Cell walls and intercellular spaces ✅
D) Nucleus

Explanation: Apoplast pathway = transport through cell walls without crossing membranes.

Q20. The symplast pathway involves

A) Cell walls
B) Vacuole
C) Cytoplasm connected by plasmodesmata ✅
D) Cuticle

Explanation: Symplast pathway = cytoplasmic route via plasmodesmata.

Q21. Which is faster: apoplast or symplast pathway?

A) Symplast
B) Apoplast ✅
C) Both equal
D) None

Explanation: Apoplast transport is faster as it doesn’t cross membranes.

Q22. Endosmosis occurs when

A) Cell placed in hypertonic solution
B) Cell placed in hypotonic solution ✅
C) Cell in isotonic solution
D) Cell in concentrated sugar solution

Explanation: Hypotonic solution → water enters cell → endosmosis.

Q23. Plasmolysis occurs when

A) Cell in hypotonic solution
B) Cell in hypertonic solution ✅
C) Cell in isotonic solution
D) Cell in pure water

Explanation: Hypertonic solution → water exits → cell shrinks (plasmolysis).

Q24. Imbibition is

A) Uptake of water by osmosis
B) Uptake of water by hydrophilic colloids ✅
C) Diffusion of gases
D) Root absorption

Explanation: Imbibition = absorption of water by colloids like starch, cellulose.

Q25. The water potential of pure water is

A) +1000
B) –1000
C) Zero ✅
D) One

Explanation: By definition, Ψ of pure water at standard conditions = 0.

🌱 Plant Physiology – Transport in Plants

Part 2 (Q26–Q50)

Q26. The Casparian strip is found in

A) Epidermis
B) Endodermis ✅
C) Cortex
D) Pericycle

Explanation: Casparian strip is a band of suberin in endodermis, regulating water entry into stele.

Q27. Which pathway is blocked by the Casparian strip?

A) Symplast
B) Apoplast ✅
C) Both symplast and apoplast
D) Transpiration

Explanation: Casparian strip blocks apoplast pathway, forcing water into symplast.

Q28. The main driving force for translocation in phloem is

A) ATP hydrolysis
B) Osmotic pressure gradient ✅
C) Root pressure
D) Active transport of K⁺ ions

Explanation: Münch hypothesis: phloem transport occurs via pressure/osmotic gradient.

Q29. Transport proteins in membranes help in

A) Active transport ✅
B) Osmosis
C) Imbibition
D) Diffusion only

Explanation: Transport proteins are essential for active and facilitated transport.

Q30. Which type of transport is uphill (against gradient)?

A) Passive diffusion
B) Facilitated diffusion
C) Active transport ✅
D) Osmosis

Explanation: Active transport uses ATP to move solutes against concentration gradient.

Q31. Facilitated diffusion differs from active transport in being

A) Energy-dependent
B) Downhill ✅
C) Against gradient
D) Endergonic

Explanation: Facilitated diffusion uses carrier proteins but no ATP (downhill).

Q32. The transpiration pull is generated due to

A) Osmosis
B) Cohesion and adhesion of water ✅
C) Root pressure only
D) Capillary action

Explanation: Cohesion + adhesion + transpiration generate negative pressure for water ascent.

Q33. Which factor increases the rate of transpiration?

A) High humidity
B) High temperature ✅
C) High CO₂
D) Darkness

Explanation: High temperature increases evaporation, thus transpiration.

Q34. Which factor reduces transpiration?

A) Wind
B) High humidity ✅
C) Sunlight
D) Temperature rise

Explanation: High humidity decreases water potential gradient → reduces transpiration.

Q35. Which ion plays a major role in stomatal opening?

A) Na⁺
B) K⁺ ✅
C) Ca²⁺
D) Mg²⁺

Explanation: Potassium ion (K⁺) accumulation in guard cells leads to stomatal opening.

Q36. Stomata open in light due to

A) Loss of K⁺
B) Uptake of K⁺ ✅
C) Loss of water
D) Active pumping of Na⁺

Explanation: In light, K⁺ ions enter guard cells, water follows osmotically → opening.

Q37. In CAM plants, stomata open during

A) Day
B) Night ✅
C) Both
D) Never

Explanation: CAM plants (cacti, succulents) open stomata at night to minimize water loss.

Q38. Which theory explains ascent of sap in tall trees?

A) Pressure-flow theory
B) Cohesion-tension theory ✅
C) Capillary theory
D) Root pressure theory

Explanation: Cohesion-tension theory is widely accepted for water transport.

Q39. Root pressure is maximum during

A) Night ✅
B) Day
C) Afternoon
D) Evening

Explanation: Root pressure develops mostly at night when transpiration is low.

Q40. The maximum root pressure recorded is about

A) 1 atm
B) 2 atm
C) 5 atm ✅
D) 20 atm

Explanation: Maximum root pressure is ~5 atm, insufficient alone for tall trees.

Q41. Which plant part shows the first response to water stress?

A) Leaves ✅
B) Roots
C) Stem
D) Flowers

Explanation: Leaves lose turgor pressure first and close stomata under water stress.

Q42. Transpiration helps in

A) Absorption of CO₂
B) Ascent of sap ✅
C) Transport of sucrose
D) ATP synthesis

Explanation: Transpiration pull is the main force for upward water transport.

Q43. The transpirational water loss in plants is

A) 1–5%
B) 10–20%
C) More than 90% ✅
D) Less than 1%

Explanation: Over 90% of absorbed water is lost by transpiration.

Q44. The main site of guttation is

A) Stomata
B) Hydathodes ✅
C) Lenticels
D) Trichomes

Explanation: Hydathodes at leaf margins secrete water droplets by guttation.

Q45. Lenticels help in

A) Photosynthesis
B) Transpiration (lenticellular) ✅
C) Absorption
D) Nitrogen fixation

Explanation: Lenticels allow gas exchange and minor water loss (lenticellular transpiration).

Q46. The cohesion of water molecules is due to

A) Ionic bonds
B) Hydrogen bonds ✅
C) Covalent bonds
D) Hydrophobic interactions

Explanation: Hydrogen bonding between water molecules gives cohesion.

Q47. The osmotic potential of a solution is always

A) Positive
B) Negative ✅
C) Zero
D) Variable

Explanation: Osmotic potential (Ψs) is always negative compared to pure water (Ψ = 0).

Q48. The pressure exerted by cell wall against turgor pressure is

A) Osmotic pressure
B) Wall pressure ✅
C) Diffusion pressure
D) Root pressure

Explanation: Wall pressure balances turgor pressure in plant cells.

Q49. If a cell is placed in hypertonic solution, it will

A) Become turgid
B) Plasmolyze ✅
C) Burst
D) Divide

Explanation: In hypertonic solution, water exits → cell shrinks (plasmolysis).

Q50. If a plasmolyzed cell is placed in hypotonic solution, it

A) Dies
B) Remains plasmolyzed
C) Becomes turgid again (deplasmolysis) ✅
D) Bursts

Explanation: Deplasmolysis occurs when water enters again → cell becomes turgid.

🌱 Plant Physiology – Transport in Plants

Part 3 (Q51–Q75)

Q51. The driving force for water absorption by roots is

A) Osmotic gradient ✅
B) Root pressure
C) Transpiration pull
D) Wall pressure

Explanation: Water enters roots primarily by osmosis due to solute gradient.

Q52. Water is pulled upward in xylem mainly due to

A) Capillarity
B) Root pressure
C) Transpiration pull ✅
D) Osmotic pressure

Explanation: Transpiration pull and cohesion–tension mechanism drive water ascent.

Q53. Which experiment demonstrated root pressure?

A) Ringing experiment
B) Porometer experiment
C) Exudation from cut stem ✅
D) Ganong’s potometer

Explanation: Exudation from cut stem in the morning indicates root pressure.

Q54. Ganong’s potometer measures

A) Osmosis
B) Guttation
C) Rate of transpiration ✅
D) Photosynthesis

Explanation: Potometer measures transpiration rate by water uptake.

Q55. Which factor closes stomata?

A) Blue light
B) Low CO₂
C) Water stress ✅
D) K⁺ influx

Explanation: Under water stress, stomata close to reduce water loss.

Q56. Antitranspirants reduce

A) Root absorption
B) Transpiration ✅
C) Photosynthesis
D) Respiration

Explanation: Antitranspirants (e.g., phenyl mercuric acetate) lower transpiration rate.

Q57. Stomatal movement is regulated by

A) Nucleus
B) Guard cell turgor ✅
C) Cuticle
D) Xylem

Explanation: Guard cells swell/shrink to regulate stomatal aperture.

Q58. The protein responsible for water transport across membranes is

A) Tubulin
B) Aquaporin ✅
C) Actin
D) Myosin

Explanation: Aquaporins are channel proteins facilitating water transport.

Q59. The pressure–flow hypothesis explains

A) Ascent of sap
B) Translocation of sugars ✅
C) Transpiration
D) Root pressure

Explanation: Münch’s pressure–flow hypothesis explains phloem transport of food.

Q60. Source to sink movement in phloem means

A) Roots → leaves
B) Leaves → growing organs ✅
C) Soil → roots
D) Xylem → stem

Explanation: Sugars move from source (leaves) to sink (roots, fruits, flowers).

Q61. Which element plays key role in osmotic regulation of guard cells?

A) Na⁺
B) K⁺ ✅
C) Cl⁻
D) Mg²⁺

Explanation: K⁺ ions regulate turgidity of guard cells → stomatal movement.

Q62. In plants, minerals are absorbed by roots mainly through

A) Diffusion
B) Active transport ✅
C) Osmosis
D) Imbibition

Explanation: Minerals are absorbed against concentration gradient using ATP.

Q63. Apoplastic movement is interrupted at

A) Epidermis
B) Casparian strip of endodermis ✅
C) Cortex
D) Pericycle

Explanation: Casparian strip forces water into symplast before entering xylem.

Q64. Cohesion–tension theory depends on

A) Root hairs
B) Hydrogen bonding in water ✅
C) Cell wall pressure
D) Lignified xylem

Explanation: Hydrogen bonds between water molecules provide cohesion.

Q65. The rate of transpiration is measured using

A) Ganong’s respirometer
B) Ganong’s potometer ✅
C) Porometer
D) Hygrometer

Explanation: Potometer measures water uptake ~ transpiration rate.

Q66. Root pressure is not sufficient in

A) Small herbs
B) Tall trees ✅
C) Seedlings
D) Aquatic plants

Explanation: Root pressure is too weak to explain water rise in tall trees.

Q67. The apoplast constitutes

A) Protoplasm
B) Cell wall + intercellular spaces ✅
C) Cytoplasm
D) Vacuole

Explanation: Apoplast = non-living continuum of cell walls and spaces.

Q68. The symplast constitutes

A) Cell walls
B) Cytoplasm interconnected by plasmodesmata ✅
C) Vacuoles
D) Xylem

Explanation: Symplast is living continuum via plasmodesmata.

Q69. Xylem sap mainly contains

A) Sugars
B) Mineral salts ✅
C) Lipids
D) Amino acids

Explanation: Xylem sap = water + dissolved mineral salts.

Q70. Phloem sap mainly contains

A) Mineral salts
B) Sucrose ✅
C) Proteins only
D) Water only

Explanation: Sucrose is main sugar translocated in phloem.

Q71. The rate of translocation in phloem is

A) 1 cm/hr
B) 1 m/hr ✅
C) 1 mm/hr
D) 10 m/hr

Explanation: Phloem translocation speed ~1 m/hr, much faster than diffusion.

Q72. The process of guttation is due to

A) Transpiration
B) Root pressure ✅
C) Capillarity
D) Osmosis

Explanation: Root pressure forces water out as droplets via hydathodes.

Q73. Transpiration serves to

A) Reduce CO₂
B) Cool leaves ✅
C) Synthesize ATP
D) Form glucose

Explanation: Transpiration cools leaves and maintains water flow.

Q74. Which structure prevents collapse of xylem under tension?

A) Casparian strip
B) Lignified walls ✅
C) Guard cells
D) Cuticle

Explanation: Lignin strengthens xylem walls, preventing collapse.

Q75. Which factor directly controls stomatal movement?

A) Guard cell turgor ✅
B) Cuticle thickness
C) Root pressure
D) Light intensity only

Explanation: Guard cell turgor is the immediate regulator of stomatal opening/closure.

🌱 Plant Physiology – Transport in Plants

Part 4 (Q76–Q100)

Q76. The water potential of a solution becomes

A) More positive when solutes are added
B) More negative when solutes are added ✅
C) Zero when solutes are added
D) Independent of solutes

Explanation: Solutes lower free energy of water, making Ψs negative.

Q77. The unit of water potential is

A) Joule
B) Bar / MPa ✅
C) Pascal only
D) Liter

Explanation: Water potential is expressed in pressure units (bars/MPa).

Q78. The pressure potential in a fully turgid cell is

A) Zero
B) Positive ✅
C) Negative
D) Always constant

Explanation: Turgid cells exert positive pressure potential (Ψp).

Q79. Osmotic potential is also called

A) Pressure potential
B) Solute potential ✅
C) Turgor potential
D) Water potential

Explanation: Ψs = solute (osmotic) potential, always negative.

Q80. The symplast pathway is slower than apoplast because

A) It involves cytoplasmic streaming ✅
B) It uses diffusion
C) It occurs via cell walls
D) It bypasses plasmodesmata

Explanation: Symplast transport is slower as solutes move through cytoplasm & plasmodesmata.

Q81. The maximum transpiration occurs from

A) Upper epidermis
B) Lower epidermis ✅
C) Stem surface
D) Cuticle

Explanation: Lower epidermis has more stomata → higher transpiration.

Q82. The opening and closing of stomata is controlled by

A) Guard cell turgor ✅
B) Mesophyll cells
C) Root hairs
D) Xylem

Explanation: Guard cell swelling/shrinking regulates stomata.

Q83. Which plant shows CAM photosynthesis to conserve water?

A) Maize
B) Cactus ✅
C) Wheat
D) Rice

Explanation: Cactus uses CAM metabolism, opening stomata at night.

Q84. Wilting is due to

A) High root pressure
B) Excessive transpiration ✅
C) Water uptake
D) Mineral deficiency only

Explanation: Excessive transpiration > absorption → water loss → wilting.

Q85. The closing of stomata under water stress is caused by

A) Increase in auxin
B) Abscisic acid (ABA) ✅
C) Gibberellins
D) Cytokinins

Explanation: ABA is a stress hormone, closes stomata to prevent water loss.

Q86. Root hair zone is important for

A) Conduction
B) Absorption of water ✅
C) Photosynthesis
D) Storage

Explanation: Root hair zone increases surface area for water/mineral absorption.

Q87. Which tissue is responsible for upward conduction of water?

A) Phloem
B) Xylem ✅
C) Cambium
D) Pericycle

Explanation: Xylem conducts water/minerals from roots to aerial parts.

Q88. The diffusion of water vapour from leaf to atmosphere is

A) Osmosis
B) Transpiration ✅
C) Guttation
D) Imbibition

Explanation: Transpiration is the diffusion of water vapour out of leaves.

Q89. The pressure that helps in phloem transport is

A) Root pressure
B) Turgor pressure ✅
C) Osmotic pressure
D) Wall pressure

Explanation: Turgor pressure difference between source and sink drives phloem transport.

Q90. The translocation in phloem is mainly

A) Unidirectional
B) Bidirectional ✅
C) Downward only
D) Upward only

Explanation: Phloem transport occurs from source → sink, which can be in both directions.

Q91. Xylem transport is always

A) Bidirectional
B) Upward (unidirectional) ✅
C) Downward only
D) Random

Explanation: Water and minerals move upward in xylem.

Q92. The transport of food is mainly in the form of

A) Glucose
B) Sucrose ✅
C) Fructose
D) Starch

Explanation: Sucrose is the translocated sugar in phloem.

Q93. When a plant cell is placed in isotonic solution

A) Water enters
B) Water exits
C) No net water movement ✅
D) Cell bursts

Explanation: In isotonic solution, osmotic potentials are equal → no net flow.

Q94. DPD (Diffusion Pressure Deficit) is equal to

A) Osmotic pressure – turgor pressure ✅
B) Turgor pressure + osmotic pressure
C) Pressure potential – osmotic pressure
D) Osmotic pressure × wall pressure

Explanation: DPD = OP – TP, driving force for water entry.

Q95. The absorption of minerals against gradient requires

A) Passive diffusion
B) Active transport ✅
C) Osmosis
D) Facilitated diffusion

Explanation: Mineral uptake often requires ATP-driven active transport.

Q96. Stomata open due to

A) Influx of K⁺ ✅
B) Loss of K⁺
C) ABA increase
D) Decrease in turgor

Explanation: K⁺ entry → water influx → guard cells swell → stomata open.

Q97. The closure of stomata is associated with

A) Loss of K⁺ ✅
B) Influx of K⁺
C) High turgor
D) Low ABA

Explanation: K⁺ efflux → water exits → guard cells shrink → stomata close.

Q98. Which one is NOT a pathway for water movement in roots?

A) Apoplast
B) Symplast
C) Transmembrane
D) Phloem pathway ✅

Explanation: Water moves by apoplast, symplast, and transmembrane routes, not phloem.

Q99. Guttation is more common in

A) Herbs ✅
B) Tall trees
C) Desert shrubs
D) Conifers

Explanation: Herbaceous plants with hydathodes show guttation more often.

Q100. The ascent of sap in tall trees is mainly explained by

A) Root pressure
B) Capillarity
C) Cohesion–tension theory ✅
D) Imbibition

Explanation: Cohesion–tension + transpiration pull is the accepted mechanism in tall trees.

Transport in plants MCQs for NEET, Plant physiology transport in plants MCQs for CBSE board, NEET biology transport in plants questions with answers, Class 11 transport in plants MCQs with explanation, Important NEET transport in plants multiple choice questions, CBSE biology transport in plants chapter wise MCQs, NCERT transport in plants MCQs for NEET and CBSE, Solved transport in plants multiple choice questions for NEET, Transport in plants NEET practice test with detailed answers, Plant physiology transport in plants objective questions for NEET and CBSE