Before You Begin
Question #46833
The Question
A researcher is studying a succulent CAM plant growing in an extremely arid environment. Due to a sudden climate anomaly, the region experiences unusually high nocturnal temperatures for several weeks, while daytime conditions remain unchanged. Based on the integration of metabolic and signaling pathways, which of the following physiological cascades is MOST likely to occur in this plant?
Options
- A.
The enzymatic efficiency of PEP carboxylase decreases, reducing vacuolar malic acid accumulation, which subsequently starves the daytime Calvin cycle and disrupts FT protein expression for floral induction.
- B.
Nocturnal CO2 fixation by RuBisCO increases to compensate for the heat stress, leading to excess malate storage in the chloroplasts and premature photoperiodic flowering.
- C.
High temperatures induce scotoactive stomatal closure at night, forcing the plant to switch to the C3 pathway during the day to maintain carbon flux for florigen synthesis.
- D.
Increased nocturnal cellular respiration depletes stored malate, causing a buildup of internal O2 during the day that promotes photorespiration and accelerates floral induction.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Stomata|C4_Pathway_Efficiency|Photoperiodism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the basic CAM cycle but fail to integrate the thermodynamic limits of enzymes (PEPcase) and the spatial/temporal separation of the pathway (Vacuole vs.
Chloroplast).
The trap lies in linking metabolic carbon-starvation to the photoperiodic FT-protein (florigen) pathway, which tests the highest level of NCERT-Plus synthesis by combining 'Photosynthesis in Higher Plants' with 'Plant Growth and Development'.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Lenticels vs Stomata |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |