The Question is from neet-botany anatomy-of-flowering-plants dicot-stem, and it was created by the author K SURESH KUMAR

Question

In a dicot stem undergoing secondary growth, the cells of the vascular cambium divide to produce secondary xylem and phloem.  If a tangential section is taken through the secondary xylem, what would be the predominant cell type observed in terms of arrangement?

K SURESH KUMAR · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Secondary growth in dicot stems and arrangement of xylem cells.
 **Related Topics**: Vascular cambium, secondary xylem, tracheary elements, parenchyma, sclerenchyma, tangential section.
 **Prerequisites**: Understanding of plant anatomy, particularly the structure of dicot stems and the process of secondary growth.
## SOLUTION PATHWAY
**Given Information**:
  Dicot stem undergoing secondary growth.
  Tangential section taken through secondary xylem.
**Method & Steps**:
 1. Understand secondary growth in dicots.  The vascular cambium produces secondary xylem towards the inside and secondary phloem towards the outside.
  Reasoning: Secondary xylem is primarily composed of tracheary elements (xylem vessels and tracheids) and parenchyma cells.
  Formula/Rule: N/A
 2. Consider a tangential section. A tangential section is cut parallel to the stem's surface, not perpendicular to the growth rings.
  Working: In a tangential section, the axially elongated tracheary elements (vessels and tracheids) will be clearly visible, arranged in a longitudinal orientation, forming the bulk of the secondary xylem.  Parenchyma cells will also be present, but their radial arrangement will be less prominent in a tangential view.
  Key Point: The arrangement of cells is crucial here.  A radial section would show the radial arrangement of parenchyma, but a tangential section highlights the axial arrangement of the tracheary elements.
 3. Identify the predominant cell type and arrangement.
  Result: Axially elongated tracheary elements are the predominant cell type observed in a tangential section of secondary xylem.
  Verification: The long, tube-like structure of tracheary elements is characteristic of secondary xylem and is best visualized in a tangential section.  
 ## OPTION ANALYSIS
A :x: Radially arranged parenchyma cells are present but are not the predominant cell type in a tangential section of secondary xylem.
B ✓: Axially elongated tracheary elements are the predominant cell type and their arrangement is clearly visible in a tangential section.
C :x: Isometric sclerenchyma cells are present in some parts of the stem, but not predominantly in the secondary xylem.
D :x: Clustered secretory cells are less common than tracheary elements in the secondary xylem.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing radial and tangential sections: Understanding the difference in the plane of section is crucial for interpreting the observed cell arrangement.
  2.Overlooking the importance of cell shape and arrangement: The question specifically asks about the predominant cell type *in terms of arrangement*.
 **Quick Tips**:
  1.Visualize a tangential section cutting through a tree trunk: You'll see the long grain of the wood, which is the axial arrangement of tracheary elements.
  2.Remember that secondary xylem is primarily for water transport, and the long tracheary elements are ideally suited for this function.

K SURESH KUMAR · Answer

Radially arranged parenchyma cells

K SURESH KUMAR · Answer

The correct Option is "Axially elongated tracheary elements"

K SURESH KUMAR · Answer

Isometric sclerenchyma cells

K SURESH KUMAR · Answer

Clustered secretory cells

NEET Botany Anatomy of Flowering Plants Dicot Stem MCQs

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