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Question #47508

Difficulty: 8/10 | 🟢 Free

The Question

Terrestrial $C_4$ plants and aquatic green algae both face the evolutionary challenge of minimizing RuBisCO's oxygenase activity under low $CO_2$ availability. Which of the following statements regarding their respective Carbon Concentrating Mechanisms (CCMs) is INCORRECT?

Options

A.
In $C_4$ plants, Kranz anatomy provides a tissue-level spatial separation to concentrate $CO_2$ , whereas green algae utilize pyrenoids as a sub-cellular micro-compartment for $CO_2$ enrichment.
B.
The primary initial $CO_2$ acceptor in the mesophyll of $C_4$ plants is a 3-carbon compound, while green algae rely directly on a 5-carbon ketose sugar within the pyrenoid.
C.
Because aqueous diffusion of $CO_2$ is highly limited, green algae compensate by utilizing PEP-carboxylase within their light-harvesting pigment complexes to actively pump $CO_2$ into the pyrenoid.
D.
While $C_4$ plants lack RuBisCO in their mesophyll chloroplasts, green algae localize the majority of their RuBisCO specifically within the proteinaceous core of the pyrenoid.

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Comparative_Analysis

Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.

Concepts Behind This Question

C-value paradox|G1/S/G2 Phases|Ploidy Levels

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: Students often conflate the biochemical adaptations of terrestrial plants (C4/PEPcase) with the biophysical adaptations of algae (Pyrenoids/Carbonic Anhydrase).

The trap in Option C exploits the 'Functional Overlap' misconception by falsely integrating the C4 biochemical pump (PEPcase) into the algal light-harvesting pigment complexes, testing if the student can strictly separate the photochemical phase (pigments) from the biosynthetic phase (carbon fixation/pyrenoids).

Quick Facts About This Question

Question Information

Subject	Biology
Chapter	Plant Kingdom - Class 11
Concept	Haplontic-Diplontic Life Cycle Transitions
Difficulty	8
Cognitive Load	5
Target Solve Time	120 sec
Access	Free