Before You Begin

Question #47664

Difficulty: 8/10 | 🟢 Free

The Question

In a wild-type $C_3$ plant, photorespiration is a wasteful process that consumes ATP and releases $CO_2$ . Suppose a genetic mutation in a $C_3$ plant significantly increases the efficiency of Substrate Level Phosphorylation (SLP) at the Phosphoglycerate Kinase (PGK) step during glycolysis. Which of the following best describes the physiological consequence of this mutation on the plant's carbon economy?

Options

A.
The net metabolic cost of photorespiration is reduced, causing the $CO_2$ compensation point to shift downward.
B.
The increased ATP yield directly inhibits RuBisCO's oxygenase activity, eliminating the $C_2$ cycle entirely.
C.
The plant will exhibit a higher $CO_2$ compensation point due to the increased rate of cytosolic respiration.
D.
The mutation will force the plant to adopt Kranz anatomy to utilize the excess ATP generated via SLP.

Check Your Answer

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

Phosphoglycerate Kinase|RuBisCO|Photorespiration

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: Understanding that the $CO_2$ compensation point is not just a fixed number, but a dynamic thermodynamic balance between photosynthetic gains and respiratory/photorespiratory costs.

Students often fail to link cytosolic SLP efficiency with whole-plant carbon economy, falling for the trap that ATP levels directly alter RuBisCO kinetics (Option B).

Quick Facts About This Question

Question Information

Subject	Biology
Chapter	Respiration in Plants - Class 11
Concept	Substrate Level Phosphorylation (SLP) Sites
Difficulty	8
Cognitive Load	5
Target Solve Time	120 sec
Access	Free