Q.128 Botany ⭐ 360° Option Elimination Active

NEET 2023 Botany Question 128 Solution

Topic: Anatomy of Flowering Plants · 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: Late wood has fewer xylary elements with narrow vessels. Reason R: Cambium is less active in winters. In the light of the above statements, choose the correct answer from the options given below:

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

✓

Verified Against NTA Final Answer Key

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

📚 Anatomy of Flowering Plants Medium

📋 Given Parameters & Problem Setup

Assertion (A) Late wood has fewer xylary elements with narrow vessels.

Reason (R) Cambium is less active in winters.

⚡

The 30-Second Exam Hall Shortcut: ⚡ Seasonal Cambial Activity: Winter Sluggishness = Late Wood

⏱️ Save ~25 seconds

In winter/autumn, vascular cambium is less active, forming fewer xylem elements with narrow lumens (late/autumn wood). In spring, cambium is highly active, producing numerous elements with wide vessels (spring/early wood)!

1 Assertion: Late wood (autumn wood) has fewer xylary elements with narrow vessels -> True.

2 Reason: In winter, climatic conditions are adverse and cambium is less active -> True.

3 Causal link: The reduced cambial activity in winter directly causes the formation of fewer elements with narrow vessels.

4 R is the correct explanation of A -> Select Option (2) Both A and R are true and R is the correct explanation of A.

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Plant Anatomy seasonal cambial kinetics.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Physiological Basis of Annual Rings

Vascular cambium activity is modulated by seasonal climatic fluctuations in temperate regions:

\begin{aligned} \text{\textbf{Spring Wood (Early Wood):}} & \quad \text{Cambium highly active} \implies \text{Many xylary elements with } \mathbf{\text{wide vessels (low density)}} \\[4pt] \text{\textbf{Late Wood (Autumn Wood):}} & \quad \mathbf{\text{Cambium less active in winter}} \implies \mathbf{\text{Fewer xylary elements with narrow vessels (high density)}} \end{aligned}

Step 2

Verbatim NCERT Reference

NCERT states verbatim: "In winter, the cambium is less active and forms fewer xylary elements that have narrow vessels, and this wood is called autumn wood or late wood."

Step 3

Assertion-Reason Causal Validation

The diminished mitotic rate of cambial fusiform initials during winter is the direct physiological cause for the anatomical traits (fewer elements, narrow vessels) of late wood. 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 factually true: late wood is characterized by narrow vessels and fewer elements.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing early wood wide vessels with late wood narrow vessels.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

Both statements are true and Reason provides the exact physiological cause for Assertion.

💡

Why this is airtight: None; rigorous physiological deduction.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Cambial activity directly controls xylary element number and vessel diameter; the link is directly causal.

⚠️

Student Fallacy (Why candidates pick this trap): Failing to recognize cambial activity as the direct driver of xylem morphology.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Reason is factually true: cambium is less active in winters in temperate zones.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming cambial activity remains constant year-round.

⚠️

NTA Trap Alert: Spring vs. Autumn Wood Property Reversal Trap

Students frequently mix up the traits: Early/Spring wood is light in color with low density and wide vessels; Late/Autumn wood is dark in color with high density and narrow vessels.

🛡️ How to avoid the -1 mark: Spring = Vigorous growth (wide vessels, high activity). Winter/Late = Dormancy (narrow vessels, low activity).

📖

Core NEET Syllabus Standard

NCERT Biology · Anatomy of Flowering Plants Standard Benchmark

Core Scientific Principle Tested:

"In winter, the cambium is less active and forms fewer xylary elements that have narrow vessels, and this wood is called autumn wood or late wood."

Syllabus Focus: Secondary Growth (Spring Wood and Autumn Wood)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Botany Question 128 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Seasonal Cambial Activity: Winter Sluggishness = Late Wood

Step-by-Step Rigorous Workflow & Mathematical Proof

Physiological Basis of Annual Rings

Verbatim NCERT Reference

Assertion-Reason Causal Validation

360° Option Elimination Engine Key Feature

NTA Trap Alert: Spring vs. Autumn Wood Property Reversal Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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