The Question is from neet-botany mineral-nutrition , and it was created by the author D VINOD

Question

The infection thread, crucial for rhizobial entry into the root hair, is primarily composed of which plant cell wall component?

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
	**Primary Concept**: Plant-microbe interactions, specifically the process of nitrogen fixation in legumes.
	**Related Topics**: Cell wall composition, root hair development, symbiosis, nitrogen cycle.
	**Prerequisites**: Basic understanding of plant cell structure and function.
## SOLUTION PATHWAY
**Given Information**: 
	Rhizobia enter root hairs through infection threads.
	The question asks about the primary component of the infection thread.
**Method & Steps**:
	1. Recall the function and formation of the infection thread.
		Reasoning: The infection thread is a tubular structure formed by the plant cell wall in response to rhizobial signals. It allows rhizobia to travel through the root hair towards the root cortex.
	2. Consider the components of the plant cell wall.
		Working: The plant cell wall is primarily composed of cellulose, hemicellulose, pectin, and lignin. Suberin is found in the Casparian strip and other specialized cell walls.
		Key Point: Cellulose provides structural support and strength to the cell wall.
	3. Identify the primary component of the infection thread.
		Result: Cellulose is the major structural component of the infection thread.
		Verification: Research confirms that the infection thread is primarily composed of cellulose, which is synthesized by the plant in response to rhizobial Nod factors.
## OPTION ANALYSIS
[A] ✓: Cellulose is the correct answer. The infection thread, which is an invagination of the plant cell wall, is primarily made of cellulose, providing a pathway for rhizobia to enter the root hair.
[B] :x: Pectin is a component of the plant cell wall, but it is not the primary structural element of the infection thread. Pectin plays a role in cell wall porosity and adhesion, but not in forming the tube-like structure of the infection thread.
[C] :x: Lignin provides rigidity and strength to plant cell walls, particularly in woody tissues. However, it is not the primary component of the infection thread, which requires flexibility for growth and extension.
[D] :x: Suberin is a hydrophobic substance found in some plant cell walls, like the Casparian strip in the root endodermis, where it acts as a barrier to water and solute movement. It is not a major component of the infection thread.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing the roles of different cell wall components:  Make sure to understand the distinct functions of cellulose, pectin, lignin, and suberin in the plant cell wall.
		2. Overlooking the importance of cellulose: Remember that cellulose is the most abundant organic polymer and provides the basic structural framework for the plant cell wall, including the infection thread.
	**Quick Tips**:
		1. Associate 'infection thread' with 'cellulose tube': This helps remember the primary composition of the infection thread.
		2.  Think of the infection thread as an extension of the plant cell wall: Since the cell wall is primarily made of cellulose, it follows that the infection thread, derived from the cell wall, would also be primarily composed of cellulose.

D VINOD · Answer

The correct Option is "Cellulose"

D VINOD · Answer

Pectin

D VINOD · Answer

Lignin

D VINOD · Answer

Suberin

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