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Question #45920

Difficulty: 8/10 | 🟢 Free

The Question

The Great Oxidation Event marked a pivotal shift in metabolic evolution, transitioning early life from anaerobic bioenergetics to aerobic respiration. Which of the following statements regarding this evolutionary and biochemical transition is INCORRECT?

Options

A.
Organisms that failed to evolve enzymatic mechanisms to neutralize reactive oxygen species were restricted to obligate anaerobic niches.
B.
The shift allowed $O_2$ to replace molecules like sulfate as the terminal electron acceptor, yielding a higher thermodynamic efficiency.
C.
In the evolved aerobic pathways, $O_2$ acts as the final hydrogen acceptor by directly oxidizing the carbon skeleton of respiratory substrates to release $CO_2$ .
D.
The endosymbiotic integration of an aerobic proteobacterium provided the ancestral eukaryotic cell with membrane-bound complexes for oxidative phosphorylation.

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Evolutionary_Exception

Tackle problems where standard rules evolve or change based on specific environmental constraints.

Concepts Behind This Question

Terminal Electron Acceptor|Chemical Evolution Sequence|Anaerobic Respiration

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: The exact biochemical role of Oxygen in cellular respiration.

Common Misconception: Students often conflate macroscopic combustion with cellular respiration, assuming inhaled $O_2$ directly binds with carbon from glucose to produce exhaled $CO_2$ .

NCERT strictly defines $O_2$ 's role as the final hydrogen acceptor in the ETC to form water, while $CO_2$ is generated earlier via decarboxylation.

Quick Facts About This Question

Question Information

Subject	Biology
Chapter	Respiration in Plants - Class 11
Concept	Terminal Electron Acceptor
Difficulty	8
Cognitive Load	5
Target Solve Time	120 sec
Access	Free