Q.129 Botany ⭐ 360° Option Elimination Active

Vault ↗

NEET 2023 Botany Question 129 Solution

Topic: Sexual Reproduction in Flowering Plants · Official NTA Booklet Code G5

Question

In angiosperm, the haploid, diploid and triploid structures of a fertilized embryo sac sequentially are:

(1)Synergids, antipodals and Polar nuclei
(2)Synergids, Primary endosperm nucleus and zygote
(3)Antipodals, synergids, and primary endosperm nucleus
(4)Synergids, Zygote and Primary endosperm nucleus

✓

Verified Against NTA Final Answer Key

Option (4) : Synergids, Zygote and Primary endosperm nucleus

📚 Sexual Reproduction in Flowering Plants Easy

📋 Given Parameters & Problem Setup

Organism Angiosperms

Ploidy Sequence Haploid (

n

), Diploid (

2n

), and Triploid (

3n

)

⚡

The 30-Second Exam Hall Shortcut: ⚡ Sequential Ploidy Check: n → 2n → 3n

⏱️ Save ~20 seconds

Match the ploidy levels sequentially: Haploid ( $n$ ) = Synergid / Antipodal; Diploid ( $2n$ ) = Zygote (from syngamy $n+n$ ); Triploid ( $3n$ ) = Primary Endosperm Nucleus / PEN (from triple fusion $2n+n$ )! Match Option (4)!

1 Identify Haploid (

n

): Synergids, Antipodals, Egg cell, Male gametes.

2 Identify Diploid (

2n

): Zygote (

n \text{ egg} + n \text{ sperm}

), secondary nucleus before fertilization.

3 Identify Triploid (

3n

): Primary Endosperm Nucleus (

2n \text{ central cell} + n \text{ sperm}

4 Check Sequence: Synergids (

n

) -> Zygote (

2n

) -> PEN (

3n

5 Match Option (4).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Angiosperm double fertilization and embryo sac cytology.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Cytological Status of Embryo Sac Cells

Analyzing the ploidy of cells present in a fertilized angiosperm embryo sac following double fertilization:

\begin{aligned} \text{\textbf{Haploid (}} n \textbf{):} & \quad \text{Synergids, Antipodals (cells of the gametophyte)} \\[4pt] \text{\textbf{Diploid (}} 2n \textbf{):} & \quad \text{Zygote } (n_{\text{egg}} + n_{\text{sperm}} \text{ via Syngamy}) \\[4pt] \text{\textbf{Triploid (}} 3n \textbf{):} & \quad \text{Primary Endosperm Nucleus/PEN } (2n_{\text{polar nuclei}} + n_{\text{sperm}} \text{ via Triple Fusion}) \end{aligned}

Step 2

Matching the Specified Sequence

The question specifically requires the sequence: haploid ( $n$ ), diploid ( $2n$ ), and triploid ( $3n$ ):

\mathbf{n \longrightarrow 2n \longrightarrow 3n} \iff \mathbf{\text{Synergids } (n) \longrightarrow \text{Zygote } (2n) \longrightarrow \text{PEN } (3n)}

Step 3

Evaluation of Distractor Options

Option (1) lists synergids ( $n$ ), antipodals ( $n$ ), polar nuclei ( $n+n$ ). Option (2) lists synergids ( $n$ ), PEN ( $3n$ ), zygote ( $2n$ )—violating sequential order. Option (3) lists antipodals ( $n$ ), synergids ( $n$ ), PEN ( $3n$ ). Only Option (4) strictly adheres to the requested $n \to 2n \to 3n$ sequence.

⭐

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:

Synergids and antipodals are both haploid ( $n$ ); lacks a diploid ( $2n$ ) and triploid ( $3n$ ) structure.

⚠️

Student Fallacy (Why candidates pick this trap): Failing to track sequential ploidy values.

2 2

✗ Incorrect

Verdict & Scientific Reason:

The sequence is $n \to 3n \to 2n$ , which violates the required $n \to 2n \to 3n$ sequence.

⚠️

Student Fallacy (Why candidates pick this trap): Overlooking that triploid PEN is placed before diploid zygote.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Antipodals and synergids are both haploid ( $n$ ); no diploid structure is represented.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing two haploid cells with a diploid structure.

4 4

✓ 100% Correct

Verdict & Scientific Reason:

Strictly satisfies the $n \to 2n \to 3n$ sequence: Synergids ( $n$ ), Zygote ( $2n$ ), Primary endosperm nucleus ( $3n$ ).

💡

Why this is airtight: None; rigorous sequence matching.

⚠️

NTA Trap Alert: Order of Words in Sequential Prompts Trap

Students readily know the ploidy of individual cells, but fail to notice that Option (2) switches the order to $n \to 3n \to 2n$ .

🛡️ How to avoid the -1 mark: Write down "n, 2n, 3n" on scratch paper and match the exact sequence term-by-term.

📖

Core NEET Syllabus Standard

NCERT Biology · Sexual Reproduction in Flowering Plants Standard Benchmark

Core Scientific Principle Tested:

"Syngamy results in the formation of a diploid zygote (2n), while triple fusion produces a triploid primary endosperm nucleus (3n). Synergids remain haploid (n)."

Syllabus Focus: Double Fertilisation

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Ready to attempt under real exam pressure?

Test your speed and accuracy in the authentic 200-minute timed NTA simulator.

Launch NEET 2023 CBT Test →

← Previous (Q.128) All Botany Questions Grid Next (Q.130) →

Spotted a mistake in this solution? Report an error (support@mycompetitiveexams.com)

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2023 question papers and NEET answer keys for private study, research, and non-commercial educational practice under Fair Dealing (Section 52(1)(a) of the Indian Copyright Act, 1957). Not affiliated with or endorsed by NTA or NMC.

NEET 2023 Botany Question 129 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Sequential Ploidy Check: n → 2n → 3n

Step-by-Step Rigorous Workflow & Mathematical Proof

Cytological Status of Embryo Sac Cells

Matching the Specified Sequence

Evaluation of Distractor Options

360° Option Elimination Engine Key Feature

NTA Trap Alert: Order of Words in Sequential Prompts Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Sexual Reproduction in Flowering Plants

Anther Structure & Dithecous Morphology

Synergids & Filiform Apparatus Function

Albuminous vs. Non-Albuminous (Exalbuminous) Seeds

Calculation of Endosperm Ploidy from Diploid Number

Solve 4 NEET Questions a Day — One per Subject