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Question #45995
The Question
Barley seeds exhibiting deep dormancy due to high Abscisic acid (ABA) levels are subjected to an extreme heat shock treatment to rapidly degrade the inhibitor. Post-treatment analysis reveals that ABA levels have plummeted and Gibberellic acid (GA) signaling has successfully reached the aleurone layer. However, the seeds still fail to germinate. Which of the following best explains this physiological stall?
Options
- A.
The extreme thermal gradient denatured α-amylase and other hydrolytic enzymes, halting endosperm mobilization despite active GA signaling.
- B.
The extreme heat denatured the starch reserves in the endosperm, rendering them resistant to enzymatic cleavage by α-amylase.
- C.
The rapid degradation of ABA prevented the necessary antagonistic activation of the aleurone layer required for starch hydrolysis.
- D.
The heat shock permanently altered the permeability of the seed coat, preventing the efflux of GA from the endosperm to the embryo.
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
Abscisic Acid (ABA)|Gibberellins (GA)|Heat Shock Proteins
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often compartmentalize plant physiology and biochemistry.
They correctly identify the ABA-GA antagonism (hormonal relief) but fail to apply the biochemical principle of enzyme denaturation (thermal limits).
The trap lies in assuming that successful hormonal signaling guarantees germination, ignoring the structural integrity of the effector proteins (α-amylase) required for endosperm mobilization.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Seed Dormancy Breaking |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |