Q.191 Zoology ⭐ 360° Option Elimination Active

NEET 2023 Zoology Question 191 Solution

Topic: Cell Cycle and Cell Division · Official NTA Booklet Code G5

Question

Given below are two statements: Statement I: During G₀ phase of cell cycle, the cell is metabolically inactive. Statement II: The centrosome undergoes duplication during S phase of interphase. In the light of the above statements, choose the most appropriate answer from the options given below:

✓

Verified Against NTA Final Answer Key

Option (1) : Statement I is incorrect but Statement II is correct.

📚 Cell Cycle and Cell Division Easy

📋 Given Parameters & Problem Setup

Statement I During G0 phase of cell cycle, the cell is metabolically inactive.

Statement II Centrosome undergoes duplication during S phase of interphase.

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The 30-Second Exam Hall Shortcut: ⚡ G0 Metabolism Rule: Metabolically ACTIVE, Not Inactive!

⏱️ Save ~20 seconds

Cells in the quiescent stage ( $G_0$ ) exit the division cycle but remain METABOLICALLY ACTIVE (synthesizing ATP and proteins, e.g., neurons and cardiac myocytes). Statement I is FALSE! Statement II is TRUE (centrosome duplicates in cytoplasm during S phase). Select Option (1)!

1 Check Statement I: Claims G0 cells are metabolically inactive -> False (NCERT: "Cells in this stage remain metabolically active but no longer proliferate").

2 Check Statement II: Centrosome duplicates in cytoplasm during S phase of interphase -> Verbatim NCERT, Correct.

3 Statement I is incorrect but Statement II is correct.

4 Match Option (1).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Cell Division interphase molecular milestones.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Evaluation of Statement I (Quiescent G0 Phase Metabolism)

Cells that suspend division (e.g., heart cells, neurons) exit $G_1$ to enter the quiescent stage ( $G_0$ ). These cells do not replicate DNA or divide, but carry out full cellular respiration, protein synthesis, and basal metabolism:

\text{\textbf{G}}_0\text{\textbf{ Cells}} \implies \mathbf{\text{Metabolically ACTIVE}} \quad (\neq \text{Inactive}) \implies \text{Statement I is } \mathbf{\text{INCORRECT}}

Step 2

Evaluation of Statement II (S-Phase Cytoplasmic Events)

During the synthesis ( $S$ ) phase in animal cells, nuclear events and cytoplasmic events proceed in parallel: 1. Nuclear event: Nuclear DNA replication ( $2C \to 4C$ ). 2. Cytoplasmic event: Centrosome (centriole pair) duplication in the cytoplasm.

\text{\textbf{S Phase}} = \begin{cases} \text{Nucleus:} & \text{DNA replication } (2C \to 4C) \\[2pt] \mathbf{\text{Cytoplasm:}} & \mathbf{\text{Centrosome duplicates}} \end{cases} \implies \text{Statement II is } \mathbf{\text{CORRECT}}

Step 3

Verbatim NCERT Reference

NCERT states verbatim: - "Cells in this stage [G0] remain metabolically active but no longer proliferate unless called on to do so." (Statement I is FALSE) - "In animal cells, during the S phase, DNA replication begins in the nucleus, and the centriole duplicates in the cytoplasm." (Statement II is TRUE)

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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

✓ 100% Correct

Verdict & Scientific Reason:

Statement I falsely calls G0 metabolically inactive; Statement II correctly identifies centrosome duplication during S phase.

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Why this is airtight: None; rigorous cell biology literacy.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Statement I is false because resting cells are actively metabolizing.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing mitotic quiescence with metabolic death/inactivity.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Statement II is a well-established textbook fact.

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Student Fallacy (Why candidates pick this trap): Assuming centrioles duplicate in G2 phase.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Both statement verdicts are completely reversed.

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Student Fallacy (Why candidates pick this trap): Inverting both cell cycle concepts.

⚠️

NTA Trap Alert: Proliferative Inactivity vs. Metabolic Inactivity Trap

Students frequently equate "not dividing" with "metabolically inactive". A heart cell in G0 pumps blood 70 times a minute and consumes massive ATP; it is extraordinarily active metabolically, it just doesn't divide!

🛡️ How to avoid the -1 mark: Remember: G0 = Mitotically inactive, but METABOLICALLY ACTIVE.

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Core NEET Syllabus Standard

NCERT Biology · Cell Cycle and Cell Division Standard Benchmark

Core Scientific Principle Tested:

"Cells in G0 stage remain metabolically active but do not proliferate. In S phase, the centriole/centrosome duplicates in the cytoplasm."

Syllabus Focus: Phases of Cell Cycle (G0 and S Phase)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Zoology Question 191 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ G0 Metabolism Rule: Metabolically ACTIVE, Not Inactive!

Step-by-Step Rigorous Workflow & Mathematical Proof

Evaluation of Statement I (Quiescent G0 Phase Metabolism)

Evaluation of Statement II (S-Phase Cytoplasmic Events)

Verbatim NCERT Reference

360° Option Elimination Engine Key Feature

NTA Trap Alert: Proliferative Inactivity vs. Metabolic Inactivity Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Cell Cycle and Cell Division

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Stages of Mitosis: Spindle Fibre Attachment to Kinetochores

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