Q.117 Botany ⭐ 360° Option Elimination Active

NEET 2023 Botany Question 117 Solution

Topic: Plant Kingdom · Official NTA Booklet Code G5

Question

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A: The first stage of gametophyte in the life cycle of moss is protonema stage. Reason R: Protonema develops directly from spores produced in capsule. In the light of the above statements, choose the most appropriate answer from the options given below:

(1)A is not correct but R is correct.
(2)Both A and R are correct and R is the correct explanation of A.
(3)Both A and R are correct but R is NOT the correct explanation of A.
(4)A is correct but R is not correct.

✓

Verified Against NTA Final Answer Key

Option (2) : Both A and R are correct and R is the correct explanation of A.

📚 Plant Kingdom Medium

📋 Given Parameters & Problem Setup

Assertion (A) The first stage of gametophyte in the life cycle of moss is protonema stage.

Reason (R) Protonema develops directly from spores produced in capsule.

⚡

The 30-Second Exam Hall Shortcut: ⚡ Spore Germination Sequence: Spore → Protonema → Leafy Stage

⏱️ Save ~30 seconds

In mosses, haploid spores shed from the sporophytic capsule germinate directly into the creeping, green, branched filamentous protonema. Because it develops directly from the spore, it is definitively the first gametophytic stage!

1 Assertion: The predominant gametophytic stage in moss has two phases: (1) Protonema stage, (2) Leafy stage. Protonema is the first stage -> Assertion is true.

2 Reason: Spores formed inside the capsule via meiosis germinate directly to produce the protonema -> Reason is true.

3 Logical link: The protonema is the first stage PRECISELY BECAUSE it develops directly upon spore germination.

4 Reason correctly explains Assertion -> Select Option (2) Both A and R are correct and R is the correct explanation of A.

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Plant Kingdom bryophyte gametogenesis developmental chronology.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Two-Stage Gametophyte of Mosses

The dominant haploid free-living gametophyte of mosses (Bryopsida, e.g., $\textit{Funaria, Polytrichum, Sphagnum}$ ) consists of two sequential phases:

\text{Moss Gametophyte (} n \text{)} = \begin{cases} \mathbf{1.\text{ Protonema Stage:}} & \text{Creeping, green, branched, filamentous} \\[4pt] \mathbf{2.\text{ Leafy Stage:}} & \text{Develops from secondary protonema buds} \end{cases}

Step 2

Direct Origin from Sporophytic Spores

Following reduction division (meiosis) inside the sporophyte capsule, haploid spores are dispersed. Upon landing on suitable moist substratum, a spore germinates directly into a primary protonema:

\text{Spore (} n \text{ from capsule)} \xrightarrow{\text{Germination}} \text{\textbf{Protonema Stage (First Gametophytic Stage)}}

Step 3

Causal Linkage Validation

Because the protonema is the direct, immediate vegetative germination product of the meiotic spore, it is canonically established as the primary/first stage of the gametophytic generation. Hence, Reason R correctly explains Assertion A.

⭐

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:

Assertion is completely correct: protonema is explicitly the first stage of the moss gametophyte.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking the erect leafy shoot is the first stage.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

Both statements are true facts from NCERT and R provides the exact causal explanation for why protonema is the first stage.

💡

Why this is airtight: None; rigorous logical deduction.

3 3

✗ Incorrect

Verdict & Scientific Reason:

There is a direct developmental causality: developing immediately from the spore is the exact definition of being the initial stage.

⚠️

Student Fallacy (Why candidates pick this trap): Failing to connect direct spore development to being the initial developmental stage.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Reason is factually correct: moss spores are formed in the capsule and germinate into protonema.

⚠️

Student Fallacy (Why candidates pick this trap): Doubting whether moss spores develop inside the sporophyte capsule.

⚠️

NTA Trap Alert: Protonema vs. Leafy Gametophyte Precedence Trap

Students frequently picture the familiar leafy moss plant and forget that it arises as a secondary lateral bud from the primary protonema.

🛡️ How to avoid the -1 mark: Remember the sequence: Spore → Protonema (1st stage) → Leafy Gametophore with sex organs (2nd stage).

📖

Core NEET Syllabus Standard

NCERT Biology · Plant Kingdom Standard Benchmark

Core Scientific Principle Tested:

"The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is the protonema stage, which develops directly from a spore."

Syllabus Focus: Bryophytes (Mosses)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Botany Question 117 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Spore Germination Sequence: Spore → Protonema → Leafy Stage

Step-by-Step Rigorous Workflow & Mathematical Proof

Two-Stage Gametophyte of Mosses

Direct Origin from Sporophytic Spores

Causal Linkage Validation

360° Option Elimination Engine Key Feature

NTA Trap Alert: Protonema vs. Leafy Gametophyte Precedence Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Plant Kingdom

Life Cycle and Morphological Features of Gymnosperms

Classification of Pteridophytes - Class Sphenopsida

Life Cycle and Alternation of Generations in Pteridophytes

Life Cycle and Chronology of Reproductive Events in Bryophytes

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