The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

Which structural feature of guard cells facilitates their function in stomatal regulation MOST effectively?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Plant cell structure and function, particularly in relation to stomatal control.
 **Related Topics**:  Cell wall structure, turgor pressure, water potential, photosynthesis, transpiration.
 **Prerequisites**: Understanding of plant cell anatomy, osmosis, and the role of stomata in gas exchange and water regulation.
## SOLUTION PATHWAY
**Given Information**:
  The question asks about the structural feature of guard cells that BEST facilitates stomatal regulation.
  Options include cell wall thickness, cellulose microfibril orientation, vacuole size, and chloroplast presence.
**Method & Steps**:
 1. Analyze each option's role in stomatal opening and closing.
  Reasoning: Stomata open and close due to changes in guard cell turgor pressure.  Changes in turgor pressure alter the shape of guard cells, controlling the stomatal pore size.
 2. Evaluate how each structural feature affects turgor pressure and guard cell shape.
  Working: 
        * **A (Uniformly thickened cell walls):** Would restrict expansion and contraction, hindering stomatal movement.
        * **B (Radially oriented cellulose microfibrils):** These microfibrils cause the guard cells to expand more in one direction (perpendicular to the microfibrils) when turgor pressure increases, leading to the characteristic curvature that opens the stomata. This is the key structural feature.
        * **C (Large central vacuole for water storage):** While important for turgor pressure, it's not the primary structural feature enabling the directional change in shape.
        * **D (Presence of chloroplasts for photosynthesis):** Photosynthesis provides ATP and reducing power, supporting active transport of ions that influence turgor pressure, but it's not the direct structural feature controlling the shape change.
 3. Identify the option that most directly influences the shape change of guard cells.
  Result: Radially oriented cellulose microfibrils (option B) are the most effective structural feature.
  Verification:  The unique arrangement of cellulose microfibrils allows for the controlled and efficient opening and closing of stomata in response to environmental changes.
 ## OPTION ANALYSIS
A :x: Uniformly thickened cell walls would prevent the necessary shape changes for stomatal regulation.
B ✓: Radially oriented cellulose microfibrils allow for differential expansion and contraction, leading to stomatal opening and closing.
C :x: A large vacuole contributes to turgor pressure but doesn't directly determine the directional expansion of guard cells.
D :x: Chloroplasts are important for energy production, but not the primary structural feature for stomatal regulation.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the role of turgor pressure with the structural features enabling it:  Turgor pressure is the driving force, but the cell wall structure dictates how that pressure affects shape.
  2.Overlooking the importance of cellulose microfibril orientation:  Students might focus on the vacuole or chloroplasts without considering the crucial role of the cell wall's architecture.
 **Quick Tips**:
  1.Remember that stomatal opening and closing is a mechanical process driven by turgor pressure and facilitated by the specific arrangement of cellulose microfibrils in the guard cell walls.
  2.Visualize the guard cells expanding and contracting; the radial orientation of the microfibrils allows for this differential expansion.

Mr. NARESH KUMAR K · Answer

Uniformly thickened cell walls.

Mr. NARESH KUMAR K · Answer

The correct Option is "Radially oriented cellulose microfibrils in the cell walls."

Mr. NARESH KUMAR K · Answer

Large central vacuole for water storage.

Mr. NARESH KUMAR K · Answer

Presence of chloroplasts for photosynthesis.

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