The Question is from NEET guide , and it was created by the author B VENKAT

Question

Which specific tissue within the root endodermis is primarily responsible for regulating the passage of water and minerals into the stele, and how does its structure facilitate this function?

B VENKAT · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
	**Primary Concept**: Plant anatomy and water transport in plants
	**Related Topics**: Root structure, apoplast and symplast pathways, Casparian strip function
	**Prerequisites**: Understanding of plant tissues, cell wall composition, and water movement mechanisms.
## SOLUTION PATHWAY
**Given Information**:
	The question asks about the specific tissue in the root endodermis regulating water and mineral passage into the stele (vascular cylinder).
	Options describe different tissues and their potential roles.
**Method & Steps**:
	1. **Identify the tissue:** The endodermis is a single layer of cells surrounding the stele.  The Casparian strip is a key feature within these cells.
		Reasoning: The question focuses on regulation, implying a barrier or control mechanism.
		Formula/Rule: N/A
	2. **Analyze the structure-function relationship:** The Casparian strip is composed of suberin, a waxy substance that is impermeable to water and dissolved minerals.
		Working: The suberin deposition in the radial and transverse walls of the endodermal cells blocks the apoplastic pathway (movement through cell walls and intercellular spaces). This forces water and minerals to enter the symplast (cytoplasm and plasmodesmata) of the endodermal cells, allowing for selective uptake.
		Key Point:  The symplastic pathway allows for regulation of which substances are transported into the stele.
	3. **Evaluate options:** Option C correctly identifies the Casparian strip and its mechanism of action.
		Result: Casparian strip
		Verification: The other options are incorrect because they either don't directly regulate passage into the stele (pericycle, cortex, phloem) or don't explain the mechanism of regulation correctly (pericycle's meristematic nature is not directly related to water/mineral regulation).
## OPTION ANALYSIS
A :x: Pericycle is involved in lateral root formation, not primarily in regulating water/mineral passage into the stele.
B :x: The cortex is external to the endodermis and doesn't actively regulate passage into the stele. Its intercellular spaces are part of the apoplast pathway, which is blocked by the Casparian strip.
C ✓: Correctly identifies the Casparian strip and its role in blocking the apoplastic pathway, forcing water and minerals to enter the symplast for regulated transport.
D :x: Phloem transports sugars and other organic compounds, not primarily involved in the initial regulation of water and mineral uptake into the stele.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing the roles of the pericycle, endodermis, and cortex:
			How to avoid: Carefully study the location and function of each tissue in the root.
		2.  Failing to understand the apoplastic and symplastic pathways:
			How to avoid: Visualize the pathways and how the Casparian strip affects them.
	**Quick Tips**:
		1. Remember the Casparian strip as a 'gatekeeper' for water and minerals entering the stele.
		2. Associate suberin with impermeability.

B VENKAT · Answer

Pericycle; its meristematic nature allows for selective uptake

B VENKAT · Answer

Cortex; its large intercellular spaces facilitate diffusion

B VENKAT · Answer

The correct Option is "Casparian strip; suberin deposition in cell walls blocks apoplastic pathway"

B VENKAT · Answer

Phloem; its active transport mechanisms selectively move nutrients

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