BIOLOGY-Plant Water Relations Questions and Answers

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Q21
What is the primary site of transpiration in most plants?
  • A Leaves
  • B Stems
  • C Roots
  • D Flowers
Answer: Option A
Explanation: Leaves contain the highest density of stomata and provide the main surface for transpirational water loss.
Q22
Which theory explains the ascent of sap in tall trees?
  • A Cohesion-tension theory
  • B Root pressure theory
  • C Imbibition theory
  • D Active transport theory
Answer: Option A
Explanation: The cohesion-tension theory best explains how water can be pulled to great heights in trees.
Q23
What is the term for the attraction between water and solid surfaces?
  • A Adhesion
  • B Cohesion
  • C Surface tension
  • D Capillarity
Answer: Option A
Explanation: Adhesion refers to water molecules sticking to other surfaces, like xylem vessel walls.
Q24
Which process describes the absorption of water by dry seeds?
  • A Imbibition
  • B Osmosis
  • C Diffusion
  • D Plasmolysis
Answer: Option A
Explanation: Imbibition is the uptake of water by hydrophilic colloids in dry seeds, causing swelling.
Q25
What is the main component of plant cell walls that affects water relations?
  • A Cellulose
  • B Lignin
  • C Pectin
  • D Hemicellulose
Answer: Option A
Explanation: Cellulose forms the structural framework of cell walls and influences water movement and retention.
Q26
Which hormone promotes stomatal closure during water stress?
  • A Abscisic acid
  • B Auxin
  • C Gibberellin
  • D Cytokinin
Answer: Option A
Explanation: Abscisic acid accumulates during drought and triggers stomatal closure to reduce water loss.
Q27
What is the term for plants adapted to dry environments?
  • A Xerophytes
  • B Hydrophytes
  • C Mesophytes
  • D Halophytes
Answer: Option A
Explanation: Xerophytes have specialized adaptations to survive in arid conditions with limited water availability.
Q28
Which process describes the movement of solutes in water?
  • A Diffusion
  • B Osmosis
  • C Active transport
  • D Bulk flow
Answer: Option A
Explanation: Diffusion is the passive movement of solutes from areas of high to low concentration.
Q29
What is the water potential of a flaccid cell?
  • A Equal to solute potential
  • B Zero
  • C Positive
  • D Maximum
Answer: Option A
Explanation: Flaccid cells have zero turgor pressure, so their water potential equals their solute potential.
Q30
Which structure allows water to move between plant cells?
  • A Plasmodesmata
  • B Stomata
  • C Casparian strip
  • D Cuticle
Answer: Option A
Explanation: Plasmodesmata are cytoplasmic channels that connect adjacent plant cells for water and solute movement.
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