Q.125 Botany ⭐ 360° Option Elimination Active

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NEET 2023 Botany Question 125 Solution

Topic: Mineral Nutrition · Official NTA Booklet Code G5

Question

Which micronutrient is required for splitting of water molecule during photosynthesis?

(1)copper
(2)manganese
(3)molybdenum
(4)magnesium

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Verified Against NTA Final Answer Key

Option (2) : manganese

📚 Mineral Nutrition Easy

📋 Given Parameters & Problem Setup

Biochemical Event Splitting of water (Photolysis) in PS II

Nutrient Category Micronutrient (Trace element)

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The 30-Second Exam Hall Shortcut: ⚡ Photolysis of Water = Manganese ( $Mn$ ) & Chlorine ( $Cl$ )

⏱️ Save ~20 seconds

The oxygen-evolving complex (OEC) of PS II contains a catalytic cluster of 4 manganese atoms ( $Mn_4CaO_5$ ). NCERT explicitly states: "The best defined function of manganese is in the splitting of water to liberate oxygen during photosynthesis!"

1 Copper: Component of plastocyanin and cytochrome oxidase, redox reactions.

2 Molybdenum: Component of nitrogenase and nitrate reductase.

3 Magnesium: Central ring atom in chlorophyll, activator for RuBisCO/PEPCase (Macronutrient).

4 Manganese: Photolysis of water to liberate oxygen (Micronutrient).

5 Match Option (2) manganese.

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Why You Can 100% Trust This Shortcut: Canonical NCERT Mineral Nutrition micronutrient physiological roles.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Mechanism of Water Splitting in Photosystem II

Photolysis occurs on the inner (lumenal) face of the thylakoid membrane associated with PS II, requiring manganese ( $Mn^{2+}$ ), calcium ( $Ca^{2+}$ ), and chloride ( $Cl^-$ ) ions:

2H_2O \xrightarrow{[Mn_4CaO_5\text{ cluster}]} 4H^+ + 4e^- + O_2\uparrow

Step 2

Verbatim NCERT Association

Under Manganese ( $Mn$ ), NCERT explicitly declares: "The best defined function of manganese is in the splitting of water to liberate oxygen during photosynthesis."

Step 3

Nutrient Classification Clarification

The question specifically stipulates "micronutrient". While magnesium ( $Mg$ ) is essential for photosynthesis as the central porphyrin ring coordinator of chlorophyll, magnesium is a macronutrient, whereas manganese is a micronutrient.

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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:

Copper participates in electron transfer as a component of plastocyanin, but does not split water.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing plastocyanin copper with the water-splitting complex.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

Matches NCERT verbatim: manganese is the key catalytic micronutrient required for the photolysis of water.

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Why this is airtight: None; textbook verbatim.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Molybdenum is an essential cofactor for nitrogenase and nitrate reductase in nitrogen metabolism.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing nitrogen fixation enzymes with oxygen-evolving complexes.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Magnesium is a macronutrient coordinated in the central ring of chlorophyll and an activator of RuBisCO; it does not split water.

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Student Fallacy (Why candidates pick this trap): Overlooking that magnesium is a macronutrient and does not catalyze photolysis.

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NTA Trap Alert: Manganese vs. Magnesium Trap

Students frequently mix up Manganese ( $Mn$ , micronutrient for photolysis) with Magnesium ( $Mg$ , macronutrient in chlorophyll core).

🛡️ How to avoid the -1 mark: Remember: Mg = in the middle of Green chlorophyll (Macro). Mn = split water to Make oxygen (Micro).

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Core NEET Syllabus Standard

NCERT Biology · Mineral Nutrition Standard Benchmark

Core Scientific Principle Tested:

"The best defined function of manganese is in the splitting of water to liberate oxygen during photosynthesis."

Syllabus Focus: Essential Mineral Elements (Manganese)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Botany Question 125 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Photolysis of Water = Manganese (MnMnMn) & Chlorine (ClClCl)

Step-by-Step Rigorous Workflow & Mathematical Proof

Mechanism of Water Splitting in Photosystem II

Verbatim NCERT Association

Nutrient Classification Clarification

360° Option Elimination Engine Key Feature

NTA Trap Alert: Manganese vs. Magnesium Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Mineral Nutrition

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Physiological Roles of Micronutrients: Iron, Zinc, Boron, and Manganese

Roles of Essential Micronutrients: Fe, Zn, B, Mo

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The 30-Second Exam Hall Shortcut: ⚡ Photolysis of Water = Manganese ( $Mn$ ) & Chlorine ( $Cl$ )