Q.141 Botany ⭐ 360° Option Elimination Active

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NEET 2021 Botany Question 141 Solution

Topic: Anatomy of Flowering Plants · Official NTA Booklet Code M1

Question

Select the correct pair.

(1)Large colorless empty - Subsidiary cells cells in the epidermis of grass leaves
(2)In dicot leaves, vascular - Conjunctive bundles are surrounded tissue by large thick-walled cells
(3)Cells of medullary rays - Interfascicular that form part of cambium cambial ring
(4)Loose parenchyma cells - Spongy rupturing the epidermis parenchyma and forming a lens- shaped opening in bark

✓

Verified Against NTA Final Answer Key

Option (3) : Cells of medullary rays that form part of cambial ring - Interfascicular cambium

📚 Anatomy of Flowering Plants Easy

📋 Given Parameters & Problem Setup

Anatomical Pairs Four structure-function / origin pairings in plant anatomy

Target Select the CORRECT pair

⚡

The 30-Second Exam Hall Shortcut: ⚡ Medullary Rays $\to$ Interfascicular Cambium (Classic Dedifferentiation!)

⏱️ Save ~20 seconds

In dicot stems, the cells of medullary rays adjoining intrafascicular cambium become meristematic (dedifferentiate) and form the interfascicular cambium, completing the continuous cambial ring! Pair (3) is 100% correct. Match Option (3)!

1 Check Pair (1): Large colorless empty epidermal cells in grasses are Bulliform cells, NOT subsidiary cells

\implies

INCORRECT.

2 Check Pair (2): In dicot leaves, vascular bundles are surrounded by bundle sheath cells, NOT conjunctive tissue

\implies

INCORRECT.

3 Check Pair (3): Cells of medullary rays forming part of cambial ring = Interfascicular cambium

\implies

CORRECT verbatim NCERT.

4 Check Pair (4): Loose parenchyma cells rupturing epidermis to form lens-shaped opening = Complementary cells / Lenticels, NOT spongy parenchyma

\implies

INCORRECT.

5 Match Option (3).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Anatomy of Flowering Plants on Cambial Ring Formation.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Formation of the Complete Cambial Ring in Dicot Stems

In young dicot stems, cambium present between primary xylem and primary phloem within a vascular bundle is the intrafascicular cambium (primary lateral meristem):

\text{Intrafascicular Cambium} + \underbrace{\text{Dedifferentiated Medullary Ray Cells}}_{\mathbf{\text{Interfascicular Cambium}}} \longrightarrow \mathbf{\text{Continuous Vascular Cambial Ring}}

Step 2

Deconstruction and Refutation of Incorrect Pairs

- Pair (1): Large, empty, colorless epidermal cells on the adaxial surface of grass leaves are bulliform (motor) cells, which control leaf rolling to minimize transpiration (subsidiary cells flank stomatal guard cells). - Pair (2): In leaves, vascular bundles are encased by a layer of tightly packed cells known as the bundle sheath (conjunctive tissue is the parenchymatous tissue between xylem and phloem in roots). - Pair (4): The loose, thin-walled parenchymatous cells produced by phellogen that rupture the epidermis are complementary cells, forming lenticels (spongy parenchyma is the loosely arranged mesophyll tissue in leaves).

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360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 1

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. These specialized cells are bulliform cells (motor cells), not subsidiary cells.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing stomatal subsidiary cells with bulliform cells.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Vascular bundles in leaves are surrounded by bundle sheath cells; conjunctive tissue is found in roots.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing leaf bundle sheath with root conjunctive tissue.

3 3

✓ 100% Correct

Verdict & Scientific Reason:

This pair is completely TRUE. Cells of medullary rays adjoining fascicular cambium dedifferentiate to form interfascicular cambium.

💡

Why this is airtight: None. Canonical textbook relationship.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. These are complementary cells of lenticels, not leaf spongy parenchyma.

⚠️

Student Fallacy (Why candidates pick this trap): Conflating aerating bark complementary cells with leaf spongy mesophyll.

⚠️

NTA Trap Alert: Intrafascicular vs Interfascicular Cambium Origin

Intrafascicular cambium is primary in origin (present in primary bundle); Interfascicular cambium is secondary in origin, formed from medullary ray cells by dedifferentiation.

🛡️ How to avoid the -1 mark: Inter = Between bundles

\implies

formed by medullary rays between the vascular bundles.

📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Anatomy of Flowering Plants Standard Benchmark

Core Scientific Principle Tested:

"In dicot stems, the cells of cambium present between primary xylem and primary phloem is the intrafascicular cambium. The cells of medullary rays, adjoining these intrafascicular cambium become active and form the interfascicular cambium."

Syllabus Focus: Secondary Growth: Vascular Cambium

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Botany Question 141 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Medullary Rays →\to→ Interfascicular Cambium (Classic Dedifferentiation!)

Step-by-Step Rigorous Workflow & Mathematical Proof

Formation of the Complete Cambial Ring in Dicot Stems

Deconstruction and Refutation of Incorrect Pairs

360° Option Elimination Engine Key Feature

NTA Trap Alert: Intrafascicular vs Interfascicular Cambium Origin

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Anatomy of Flowering Plants

Anatomical Characteristics of Monocotyledonous Stem

Stomatal Apparatus and Guard Cell Architecture

Collenchyma Living Nature and Gymnosperm Xylem Composition

Bulliform Cells and Inward Leaf Rolling in Monocots

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The 30-Second Exam Hall Shortcut: ⚡ Medullary Rays $\to$ Interfascicular Cambium (Classic Dedifferentiation!)