The Question is from neet-botany , and it was created by the author NISHANTH

Question

The passage cells in the endodermis of a dicot root are characterized by the absence of which Casparian strip component?

NISHANTH · Accepted Answer

## CORE INFORMATION
✓ **Answer**: 2 (Suberin lamellae)
## CONCEPT FRAMEWORK
 **Primary Concept**: Plant anatomy, specifically the structure and function of the endodermis in dicot roots.
 **Related Topics**: Casparian strip, apoplastic and symplastic pathways, water transport in plants.
 **Prerequisites**: Basic understanding of plant cell structure, tissue types, and the role of the endodermis in regulating water and nutrient uptake.
## SOLUTION PATHWAY
**Given Information**:
  The question focuses on passage cells in the endodermis of a dicot root.
  Passage cells are specialized cells that allow for the radial movement of water and solutes.
  The Casparian strip is a band of suberin that is deposited in the radial and transverse walls of the endodermal cells.
**Method & Steps**:
 1. Identify the components of the Casparian strip: The Casparian strip is primarily composed of suberin, lignin, and sometimes pectin.  Cellulose is a component of the cell wall but not specifically of the Casparian strip itself.
  Reasoning: Understanding the composition of the Casparian strip is crucial.
  Formula/Rule: None directly applicable.
 2. Consider the function of passage cells: Passage cells are modified endodermal cells that lack a fully developed Casparian strip, allowing for a bypass of the usual apoplastic pathway.
  Working:  Since passage cells need to allow for water and solute movement, the component preventing this movement (the Casparian strip) must be absent or reduced in these cells.
  Key Point: The Casparian strip's function is to regulate water and nutrient uptake by preventing apoplastic flow.
 3. Determine which component is absent in passage cells: Because the Casparian strip is primarily composed of suberin,  passage cells are characterized by the absence or a significant reduction of suberin lamellae in their radial and transverse walls.
  Result: Suberin lamellae are the primary component absent in the Casparian strip of passage cells.
  Verification: The absence of suberin allows for the symplastic movement of water and solutes through the passage cells.
 ## OPTION ANALYSIS
[A] Lignin: :x: Lignin is a component of the Casparian strip, but it's not the primary component that's absent in passage cells.  Passage cells still have some lignin.
[B] Suberin lamellae: ✓: Suberin lamellae are the main component of the Casparian strip and their absence defines the passage cells.
[C] Cellulose: :x: Cellulose is a structural component of plant cell walls, but it's not a defining feature of the Casparian strip's absence in passage cells.
[D] Pectin: :x: Pectin is present in plant cell walls but isn't the primary component missing from the Casparian strip in passage cells.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the functions of the Casparian strip and passage cells: Understanding the contrasting roles is crucial.
  2.Assuming that all endodermal cells have identical Casparian strips: Passage cells are exceptions.
 **Quick Tips**:
  1.Remember that passage cells are specialized for water and solute transport.
  2.Visualize the Casparian strip as a barrier that passage cells circumvent.

NISHANTH · Answer

Lignin

NISHANTH · Answer

The correct Option is "Suberin lamellae"

NISHANTH · Answer

Cellulose

NISHANTH · Answer

Pectin

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