Q.140 Botany ⭐ 360° Option Elimination Active

NEET 2024 Botany Question 140 Solution

Topic: Photosynthesis in Higher Plants · Official NTA Booklet Code T1

Question

cm and an eye piece of focal length 5.0 cm. in figure. It travels through the prism parallel to The magnifying power of telescope for viewing its base BC and emerges along the face AC. The a distant object is: refractive index of the prism is: (1)17 (2)32 (3) 34 (4）2 28 37 Two heaters A and B have power rating of 1 kW and 2 kW,respectively. Those two are first connected in series and theninparallelto a fixed B power source. The ratio of power outputs for these two cases is: V3 (1)1:2 (2) 2:3 (1) (2) 4 2 (3)

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Verified Against NTA Final Answer Key

Option (1) : Statement I is true but Statement II is false

📚 Photosynthesis in Higher Plants Medium

📋 Given Parameters & Problem Setup

Statement I In C3 plants, some O2 binds to RuBisCO, hence CO2 fixation is decreased.

Statement II In C4 plants, mesophyll cells show very little photorespiration while bundle sheath cells do not show photorespiration.

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The 30-Second Exam Hall Shortcut: ⚡ C4 Photorespiration Absolute Rule

⏱️ Save ~30 seconds

Photorespiration does NOT occur at all in C4 plants (not "very little in mesophyll")! RuBisCO is completely absent in C4 mesophyll cells! Statement II is false; Statement I is true!

1 Statement I: In C3 plants, RuBisCO has an oxygenase activity; binding of O₂ decreases CO₂ fixation and initiates photorespiration -> TRUE.

2 Statement II: In C4 plants, mesophyll cells lack RuBisCO entirely (PEPcase fixes CO₂), so photorespiration cannot occur in mesophyll; bundle sheath cells have high CO₂ around RuBisCO, completely eliminating photorespiration. Thus, photorespiration is completely absent in C4 plants -> Statement II is FALSE!

3 Conclusion: Statement I is true but Statement II is false -> Option (1) / A.

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Why You Can 100% Trust This Shortcut: NCERT Biology · Photosynthesis in Higher Plants (Photorespiration in C3 and C4 Plants)

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Evaluate Statement I (C3 Oxygenase Activity)

RuBisCO is the most abundant enzyme in the world and has an active site that can bind both $CO_2$ and $O_2$ . In $C_3$ plants, some $O_2$ binds to RuBisCO, and hence $CO_2$ fixation is decreased. The RuBP instead of being converted to 2 molecules of PGA binds with $O_2$ to form one molecule of phosphoglycerate and one molecule of phosphoglycolate. Statement I is true.

Step 2

Evaluate Statement II (C4 Photorespiration Absence)

In $C_4$ plants photorespiration does not occur. This is because they have a mechanism that increases the concentration of $CO_2$ at the enzyme site. In $C_4$ plants, mesophyll cells completely lack RuBisCO (they possess PEPcase); therefore, photorespiration cannot happen in mesophyll cells. When $C_4$ acids from mesophyll cells are broken down in bundle sheath cells, $CO_2$ is released, ensuring that RuBisCO functions exclusively as a carboxylase. Thus, photorespiration is zero in both cell types. Statement II is false.

Step 3

Select Matching Option

Statement I is true but Statement II is false, matching Option (1).

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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 correctly describes RuBisCO oxygenation in C3 plants; Statement II falsely claims mesophyll cells show photorespiration in C4 plants.

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Why this is airtight: None.

2 (2)

✗ Incorrect

Verdict & Scientific Reason:

Statement I is true and Statement II is false.

⚠️

Student Fallacy (Why candidates pick this trap): Statement I is true and Statement II is false.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

Statement II is false because C4 plants do not exhibit photorespiration at all.

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Student Fallacy (Why candidates pick this trap): Statement II is false because C4 plants do not exhibit photorespiration at all.

4 (4)

✗ Incorrect

Verdict & Scientific Reason:

Statement I is factually correct.

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Student Fallacy (Why candidates pick this trap): Statement I is factually correct.

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NTA Trap Alert: Assuming "A Little" Photorespiration Occurs in C4

Thinking photorespiration happens at low rates in mesophyll of C4 plants.

🛡️ How to avoid the -1 mark: RuBisCO is entirely absent in C4 mesophyll cells, making photorespiration physically impossible there.

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Core NEET Syllabus Standard

Biology Core Botany · Photosynthesis in Higher Plants Standard Benchmark

Core Scientific Principle Tested:

"In C3 plants some O2 does bind to RuBisCO, and hence CO2 fixation is decreased... In C4 plants photorespiration does not occur. This is because they have a mechanism that increases the concentration of CO2 at the enzyme site."

Syllabus Focus: Photorespiration in C3 Plants vs Lack of Photorespiration in C4 Plants

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2024 Botany Question 140 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ C4 Photorespiration Absolute Rule

Step-by-Step Rigorous Workflow & Mathematical Proof

Evaluate Statement I (C3 Oxygenase Activity)

Evaluate Statement II (C4 Photorespiration Absence)

Select Matching Option

360° Option Elimination Engine Key Feature

NTA Trap Alert: Assuming "A Little" Photorespiration Occurs in C4

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Photosynthesis in Higher Plants

RuBisCO Oxygenase Catalysis & Identification of 2-Phosphoglycolate

Reaction Centre Chlorophyll a in Photosystem I (P700)

Chronological Sequence of Classic Photosynthesis Experiments

Stoichiometry of the Calvin Cycle (C3 Pathway) per Glucose Formed

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