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Question #45291
The Question
During a severe heatwave, an angiosperm experiences high-temperature stress just before the shedding of its 2-celled pollen grains. Assuming the pollen lands on a compatible stigma and the vegetative cell successfully forms a pollen tube guided by the filiform apparatus, which of the following best explains the subsequent failure of seed set?
Options
- A.
Heat-induced denaturation of tubulin prevents the meiotic division of the generative cell, resulting in a single diploid male gamete.
- B.
Thermal stress disrupts the spindle geometry in the generative cell, arresting its mitosis and preventing the formation of two male gametes required for double fertilization.
- C.
The high temperature denatures the hydrolytic enzymes of the filiform apparatus, preventing the discharge of male gametes into the synergid.
- D.
The vegetative nucleus undergoes mitotic arrest due to spindle depolymerization, halting pollen tube elongation in the style.
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
Generative Cell Division|Synergid Filiform Apparatus|Male Gamete
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question tests the synthesis of cell biology (spindle apparatus/tubulin denaturation) with plant reproduction (microgametogenesis).
The primary trap (Option A) exploits the common misconception that plant gametes are formed directly by meiosis, whereas in plants, the generative cell undergoes mitosis.
Option D traps students who confuse the functions of the vegetative and generative nuclei.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell Cycle and Cell Division - Class 11 |
| Concept | Spindle Attachment Geometry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |