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Question #45945
The Question
A plant is subjected to severe drought stress, triggering a surge in Abscisic Acid (ABA) levels. Two leaves on this plant, Leaf X (initial area 5 cm²) and Leaf Y (initial area 50 cm²), both exhibit a highly restricted absolute growth of exactly 1 cm² over a week due to ABA-induced stomatal closure and metabolic dormancy. Which of the following statements correctly correlates the growth parameters of these leaves with the physiological action of ABA?
Options
- A.
ABA completely halts Relative Growth Rate (RGR) in both leaves, making their Absolute Growth Rate (AGR) zero.
- B.
Despite ABA's antagonistic effect on growth promoters, Leaf X exhibits a higher Relative Growth Rate (RGR) than Leaf Y, though their Absolute Growth Rates (AGR) are identical.
- C.
ABA reduces the Relative Growth Rate (RGR) of Leaf Y more than Leaf X because ABA specifically targets and degrades mature tissues faster than young tissues.
- D.
The Absolute Growth Rate (AGR) of Leaf Y is higher than Leaf X because its larger surface area overcomes ABA-induced stomatal closure, while their RGR remains equal.
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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
Abscisic Acid (ABA) Antagonism|Absolute vs Relative Growth
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the physiological inhibition of growth (biomass accumulation via ABA) with the mathematical calculation of Relative Growth Rate (RGR).
The trap lies in assuming that a potent stress hormone like ABA will uniformly suppress all growth metrics, causing students to overlook the NCERT principle that a smaller initial size (Leaf X) mathematically results in a higher RGR even when absolute growth is severely restricted.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Absolute vs Relative Growth |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |