Q.130 Botany ⭐ 360° Option Elimination Active

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NEET 2023 Botany Question 130 Solution

Topic: Plant Growth and Development · Official NTA Booklet Code G5

Question

Which hormone promotes internode/petiole elongation in deep water rice?

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Verified Against NTA Final Answer Key

Option (4) : Ethylene

📚 Plant Growth and Development Easy

📋 Given Parameters & Problem Setup

Plant System Deep water rice plants

Hormonal Effect Rapid internode/petiole elongation allowing shoot to stay above water

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The 30-Second Exam Hall Shortcut: ⚡ Deep Water Rice Anchor: Ethylene = Shoot Elongation Above Water

⏱️ Save ~20 seconds

While gibberellin promotes general stem elongation, the specific adaptation in deep water rice plants where flooding triggers rapid internode and petiole elongation to keep foliage above water is mediated exclusively by Ethylene!

1 Submergence traps the gaseous hormone ethylene within submerged tissues.

2 High internal ethylene concentration triggers rapid stem/internode/petiole extension.

3 Foliage stays above the rising floodwaters, facilitating gas exchange.

4 Verbatim NCERT Plant Growth and Development assigns this role to Ethylene.

5 Match Option (4) Ethylene.

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Why You Can 100% Trust This Shortcut: Canonical NCERT Plant Growth Regulators ethylene physiological functions.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Physiological Adaptation to Submergence

In deep water rice varieties (e.g., lowland flood-prone cultivars), rising floodwaters submerge the lower plant body. Gas diffusion in water is $10^4$ times slower than in air, trapping endogenous ethylene gas inside tissues:

\text{Submergence} \longrightarrow \text{Entrapment of Ethylene } (C_2H_4) \longrightarrow \text{\textbf{Rapid Internode \& Petiole Elongation}}

Step 2

Verbatim NCERT Statement

NCERT states under Ethylene: "Ethylene promotes rapid internode and petiole elongation in deep water rice plants. It helps leaves/upper parts of the shoot to remain above water."

Step 3

Evaluation of Distractor Hormones

2,4-D is a synthetic auxin herbicide. $GA_3$ promotes bolting in rosette plants and stem elongation in sugarcane, but is not the NCERT answer for deep water rice. Kinetin is a cytokinin promoting cell division.

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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:

2,4-D (2,4-dichlorophenoxyacetic acid) is a synthetic auxin widely used as a selective weedicide for dicots.

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Student Fallacy (Why candidates pick this trap): Confusing herbicide applications with submergence adaptations.

2 2

✗ Incorrect

Verdict & Scientific Reason:

While gibberellin promotes stem elongation in sugarcane and bolting, ethylene is the specific regulator cited in NCERT for deep water rice.

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Student Fallacy (Why candidates pick this trap): Associating all stem elongation reflexively with gibberellins.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Kinetin is an adenine-derived cytokinin involved in cell division and overcoming apical dominance.

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Student Fallacy (Why candidates pick this trap): Confusing cytokinins with elongation hormones.

4 4

✓ 100% Correct

Verdict & Scientific Reason:

Matches NCERT verbatim: ethylene uniquely promotes internode and petiole elongation in deep water rice.

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Why this is airtight: None; textbook verbatim.

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NTA Trap Alert: Gibberellin vs. Ethylene Elongation Trap

Because gibberellins are the primary stem elongation hormone across plants, students automatically select GA₃ without recalling the unique NCERT exception for deep water rice.

🛡️ How to avoid the -1 mark: Remember that deep water rice elongation is a classic flooding escape mechanism driven by ethylene gas entrapment.

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Core NEET Syllabus Standard

NCERT Botany · Plant Growth and Development Standard Benchmark

Core Scientific Principle Tested:

"Ethylene promotes rapid internode and petiole elongation in deep water rice plants to keep photosynthetic organs above flood levels."

Syllabus Focus: Plant Growth Regulators — Ethylene

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Botany Question 130 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Deep Water Rice Anchor: Ethylene = Shoot Elongation Above Water

Step-by-Step Rigorous Workflow & Mathematical Proof

Physiological Adaptation to Submergence

Verbatim NCERT Statement

Evaluation of Distractor Hormones

360° Option Elimination Engine Key Feature

NTA Trap Alert: Gibberellin vs. Ethylene Elongation Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Plant Growth and Development

Auxins & Synthetic Auxin Applications as Herbicides

Physiological Effects of Gibberellins - Bolting in Rosette Plants

Mathematical Modeling of Arithmetic Growth (Linear Growth Kinetics)

Physiological Roles of Cytokinins (Richmond-Lang Effect)

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