MCQs on Transport in Plants – CBSE Class 11 Biology
MCQs on Transport in Plants – CBSE Class 11 Biology (Unit IV | NCERT-Based)
CBSE Class 11 Biology – MCQs with Answers and Explanations
Unit IV: Plant Physiology
Topic: Transport in Plants
Section A: Means of Transport & Diffusion (Q1–Q10)
Q1. Movement of molecules from a region of higher concentration to lower concentration is called:
A. Active transport
B. Diffusion
C. Osmosis
D. Mass flow
Answer: B
Explanation: Diffusion is a passive process driven by a concentration gradient.
Q2. Diffusion does not require:
A. Concentration gradient
B. Semi-permeable membrane
C. Kinetic energy
D. Time
Answer: B
Explanation: Diffusion can occur with or without a membrane.
Q3. Which factor does NOT affect diffusion rate?
A. Temperature
B. Size of molecules
C. Concentration gradient
D. ATP availability
Answer: D
Explanation: Diffusion is a passive process and does not require ATP.
Q4. Movement of water across a semi-permeable membrane is called:
A. Diffusion
B. Active transport
C. Osmosis
D. Translocation
Answer: C
Explanation: Osmosis is the diffusion of water through a semi-permeable membrane.
Q5. A cell placed in hypotonic solution will:
A. Shrink
B. Remain unchanged
C. Burst
D. Lose water
Answer: C
Explanation: Water enters the cell causing endosmosis, leading to swelling or bursting.
Q6. When a plant cell is placed in hypertonic solution, it undergoes:
A. Turgidity
B. Deplasmolysis
C. Plasmolysis
D. Imbibition
Answer: C
Explanation: Water leaves the cell causing plasmolysis.
Q7. Facilitated diffusion differs from simple diffusion because it:
A. Requires ATP
B. Uses carrier proteins
C. Occurs against gradient
D. Is slower
Answer: B
Explanation: Facilitated diffusion uses specific membrane proteins.
Q8. Which transport is highly selective?
A. Diffusion
B. Osmosis
C. Facilitated diffusion
D. Mass flow
Answer: C
Explanation: Carrier proteins make facilitated diffusion selective.
Q9. Imbibition is the absorption of:
A. Minerals
B. Gases
C. Water by solids
D. Sugars
Answer: C
Explanation: Imbibition occurs when hydrophilic colloids absorb water.
Q10. Which substance shows maximum imbibition?
A. Cellulose
B. Proteins
C. Starch
D. Lipids
Answer: B
Explanation: Proteins have high imbibitional capacity.
Section B: Active Transport & Water Potential (Q11–Q20)
Q11. Active transport differs from passive transport because it:
A. Occurs along gradient
B. Requires ATP
C. Is non-selective
D. Is slow
Answer: B
Explanation: Active transport moves substances against concentration gradient using energy.
Q12. Carrier proteins involved in active transport are:
A. Non-specific
B. Reversible
C. Highly specific
D. Temporary
Answer: C
Explanation: Active transport carriers are highly specific.
Q13. Water potential is denoted by:
A. Ψp
B. Ψs
C. Ψw
D. Ψg
Answer: C
Explanation: Water potential is symbolized as Ψw.
Q14. Pure water has water potential:
A. Zero
B. Negative
C. Positive
D. Infinite
Answer: A
Explanation: Pure water at standard conditions has Ψw = 0.
Q15. Addition of solute to water makes its water potential:
A. Zero
B. Positive
C. More negative
D. Unchanged
Answer: C
Explanation: Solutes decrease free energy, making Ψw negative.
Q16. Pressure potential is always:
A. Negative
B. Zero
C. Positive
D. Variable
Answer: C
Explanation: Pressure potential (Ψp) is positive in living cells.
Q17. Which component lowers water potential?
A. Pressure potential
B. Solute potential
C. Gravity potential
D. Temperature
Answer: B
Explanation: Solute potential (Ψs) is always negative.
Q18. Turgidity in plant cells is due to:
A. Osmotic loss of water
B. Plasmolysis
C. Positive pressure potential
D. Diffusion
Answer: C
Explanation: Entry of water creates turgor pressure.
Q19. Which movement of water occurs from cell to cell through cell walls?
A. Symplast
B. Apoplast
C. Transmembrane
D. Mass flow
Answer: B
Explanation: Apoplast pathway uses cell walls and intercellular spaces.
Q20. Symplast pathway involves movement through:
A. Cell walls
B. Intercellular spaces
C. Cytoplasm via plasmodesmata
D. Xylem vessels
Answer: C
Explanation: Symplast pathway occurs through cytoplasmic connections.
Section C: Absorption of Water & Root Pressure (Q21–Q35)
Q21. Water absorption in plants occurs mainly through:
A. Stem
B. Leaves
C. Root hairs
D. Cortex
Answer: C
Explanation: Root hairs provide large surface area for absorption.
Q22. Passive absorption of water depends mainly on:
A. Root metabolism
B. Transpiration pull
C. ATP
D. Osmotic pressure
Answer: B
Explanation: Passive absorption is driven by transpiration pull.
Q23. Active absorption of water requires:
A. Transpiration
B. Root pressure
C. Metabolic energy
D. Xylem vessels
Answer: C
Explanation: Active absorption depends on energy from respiration.
Q24. Root pressure is maximum during:
A. Day
B. Night
C. Noon
D. Afternoon
Answer: B
Explanation: Root pressure is higher at night due to low transpiration.
Q25. Guttation occurs due to:
A. Transpiration
B. Root pressure
C. Diffusion
D. Osmosis
Answer: B
Explanation: Excess root pressure forces water out through hydathodes.
Q26. Which structure is involved in guttation?
A. Stomata
B. Lenticels
C. Hydathodes
D. Root hairs
Answer: C
Explanation: Hydathodes release water droplets during guttation.
Q27. Root pressure alone cannot account for ascent of sap in tall trees because:
A. It is absent
B. It is too weak
C. Xylem is dead
D. Leaves block flow
Answer: B
Explanation: Root pressure is insufficient to raise water to great heights.
Q28. Which mineral is absorbed by diffusion?
A. Potassium
B. Calcium
C. Nitrate
D. Magnesium
Answer: B
Explanation: Calcium moves mainly by passive diffusion.
Q29. Which mineral is absorbed actively?
A. Calcium
B. Magnesium
C. Potassium
D. Chloride
Answer: C
Explanation: Potassium uptake occurs via active transport.
Q30. Endodermis controls water movement due to presence of:
A. Root hairs
B. Casparian strips
C. Xylem vessels
D. Cortex
Answer: B
Explanation: Casparian strips block apoplast movement.
Q31. Which theory explains ascent of sap?
A. Root pressure theory
B. Capillarity theory
C. Transpiration pull theory
D. Diffusion theory
Answer: C
Explanation: Cohesion–tension theory explains ascent of sap.
Q32. Transpiration pull is generated due to:
A. Root pressure
B. Loss of water from leaves
C. Osmosis in roots
D. Mineral uptake
Answer: B
Explanation: Evaporation from leaf surface creates negative pressure.
Q33. Cohesion refers to attraction between:
A. Water and xylem walls
B. Water molecules
C. Xylem cells
D. Water and minerals
Answer: B
Explanation: Cohesion maintains continuous water column.
Q34. Adhesion refers to attraction between:
A. Water molecules
B. Minerals
C. Water and xylem walls
D. Solutes
Answer: C
Explanation: Adhesion helps water adhere to xylem walls.
Q35. Which tissue conducts water?
A. Phloem
B. Cambium
C. Xylem
D. Cortex
Answer: C
Explanation: Xylem conducts water and minerals.
Section D: Transpiration & Translocation of Food (Q36–Q50)
Q36. Loss of water in vapour form from aerial parts is called:
A. Guttation
B. Bleeding
C. Transpiration
D. Osmosis
Answer: C
Explanation: Transpiration occurs mainly through stomata.
Q37. Maximum transpiration occurs through:
A. Cuticle
B. Lenticels
C. Stomata
D. Roots
Answer: C
Explanation: Stomatal transpiration accounts for major water loss.
Q38. Opening and closing of stomata is controlled by:
A. Epidermal cells
B. Guard cells
C. Mesophyll cells
D. Xylem
Answer: B
Explanation: Guard cells regulate stomatal movement.
Q39. Which factor increases transpiration rate?
A. High humidity
B. Low temperature
C. High wind velocity
D. Darkness
Answer: C
Explanation: Wind removes moist air, increasing transpiration.
Q40. Transpiration helps plants in:
A. Cooling
B. Mineral absorption
C. Ascent of sap
D. All of these
Answer: D
Explanation: Transpiration has multiple physiological roles.
Q41. Food transport in plants occurs through:
A. Xylem
B. Cambium
C. Phloem
D. Cortex
Answer: C
Explanation: Phloem transports organic solutes.
Q42. The movement of food from leaves to other parts is called:
A. Translocation
B. Transpiration
C. Diffusion
D. Osmosis
Answer: A
Explanation: Translocation occurs via phloem tissue.
Q43. The main carbohydrate transported in phloem is:
A. Glucose
B. Fructose
C. Starch
D. Sucrose
Answer: D
Explanation: Sucrose is the primary transport sugar.
Q44. Which cells are involved in phloem transport?
A. Tracheids
B. Vessels
C. Sieve tubes and companion cells
D. Fibres
Answer: C
Explanation: Sieve tubes and companion cells work together.
Q45. The pressure flow hypothesis was proposed by:
A. Dixon and Joly
B. Stephen Hales
C. Munch
D. Darwin
Answer: C
Explanation: Munch proposed the pressure flow hypothesis.
Q46. According to pressure flow hypothesis, food movement is:
A. Passive diffusion
B. Active process
C. Mass flow due to pressure gradient
D. Osmotic movement
Answer: C
Explanation: High pressure at source drives flow to sink.
Q47. Source refers to:
A. Storage organ only
B. Root only
C. Photosynthesizing leaves
D. Growing buds
Answer: C
Explanation: Source produces and exports sugars.
Q48. Sink refers to:
A. Leaves
B. Storage organs
C. Xylem
D. Stomata
Answer: B
Explanation: Sink consumes or stores food.
Q49. Which experiment supports translocation through phloem?
A. Ringing experiment
B. Plasmolysis
C. Diffusion test
D. Osmosis
Answer: A
Explanation: Ringing experiment shows food moves via phloem.
Q50. Which plant tissue is living and involved in transport?
A. Xylem vessels
B. Tracheids
C. Phloem
D. Fibres
Answer: C
Explanation: Phloem is a living tissue responsible for food transport.