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NEET 2021 Botany Question 123 Solution

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

Question

Diadelphous stamens are found in:

(1)China rose
(2)Citrus
(3)Pea
(4)China rose and citrus

✓

Verified Against NTA Final Answer Key

Option (3) : Pea

📚 Morphology of Flowering Plants Easy

📋 Given Parameters & Problem Setup

Stamen Arrangement Diadelphous (filaments united into two distinct bundles)

⚡

The 30-Second Exam Hall Shortcut: ⚡ "Pea = Diadelphous (9)+1" | "China Rose = Monadelphous" | "Citrus = Polyadelphous"

⏱️ Save ~15 seconds

The classic NCERT androecium trio: China rose is monadelphous (1 bundle), Pea is diadelphous (2 bundles: (9)+1), and Citrus is polyadelphous (many bundles)! Looking for diadelphous stamens leads directly to Pea (*Pisum sativum*). Match Option (3)!

1 Monadelphous: Stamens united into one bundle

\implies

China rose (*Hibiscus*).

2 Diadelphous: Stamens united into two bundles

\implies

Pea (*Pisum sativum*, Fabaceae).

3 Polyadelphous: Stamens united into more than two bundles

\implies

Citrus (lemon/orange).

4 Match Option (3).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Morphology of Flowering Plants on Androecium Cohesion.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Definition of Stamen Cohesion Types

When the filaments of stamens are fused together while anthers remain free, the condition is termed adelphy:

\begin{aligned} \text{\textbf{Monadelphous:}} & \quad \text{United into a single staminal tube (e.g., China rose)} \\[4pt] \text{\textbf{Diadelphous:}} & \quad \mathbf{\text{United into two distinct bundles (e.g., Pea: } (9) + 1\text{)}} \\[4pt] \text{\textbf{Polyadelphous:}} & \quad \text{United into more than two bundles (e.g., Citrus)} \end{aligned}

Step 2

Androecium in Family Fabaceae (Pea)

In the pea flower (*Pisum sativum*, family Fabaceae), there are 10 stamens. Nine stamens fuse by their filaments into a common sheath enclosing the ovary, while the tenth posterior stamen remains free. This configuration is denoted in the floral formula as $\mathbf{A_{(9)+1}}$ , representing the classic diadelphous condition.

⭐

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:

China rose (family Malvaceae) possesses monadelphous stamens fused into a single staminal tube around the style.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing monadelphous (China rose) with diadelphous (pea).

2 2

✗ Incorrect

Verdict & Scientific Reason:

Citrus possesses polyadelphous stamens united into several distinct bundles.

⚠️

Student Fallacy (Why candidates pick this trap): Conflating polyadelphous with diadelphous.

3 3

✓ 100% Correct

Verdict & Scientific Reason:

Pea exhibits the characteristic diadelphous androecium where filaments form two bundles: (9) + 1.

💡

Why this is airtight: None. Direct textbook exemplar.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Neither China rose (monadelphous) nor Citrus (polyadelphous) is diadelphous.

⚠️

Student Fallacy (Why candidates pick this trap): Selecting a paired distractor without verifying individual adelphic states.

⚠️

NTA Trap Alert: Monadelphous vs Diadelphous vs Polyadelphous Triad

NCERT defines all three consecutively in a single paragraph. Candidates often mix up the exemplar plants across the three terms.

🛡️ How to avoid the -1 mark: Use the mnemonic: "1-China, 2-Pea, Many-Citrus"

\implies

Mono = China rose, Di = Pea, Poly = Citrus.

📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Morphology of Flowering Plants Standard Benchmark

Core Scientific Principle Tested:

"The stamens may be united into one bunch or one bundle (monadelphous) as in China rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus."

Syllabus Focus: The Flower: Androecium

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Botany Question 123 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "Pea = Diadelphous (9)+1" | "China Rose = Monadelphous" | "Citrus = Polyadelphous"

Step-by-Step Rigorous Workflow & Mathematical Proof

Definition of Stamen Cohesion Types

Androecium in Family Fabaceae (Pea)

360° Option Elimination Engine Key Feature

NTA Trap Alert: Monadelphous vs Diadelphous vs Polyadelphous Triad

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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