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Question #45486
The Question
In 60% of angiosperms, pollen grains are shed at the 2-celled stage. Suppose these pollen grains germinate on a compatible stigma that has been experimentally treated with a targeted concentration of colchicine. Assuming the pollen tube continues to grow down the style, which of the following represents the most accurate cytological outcome and its consequence on fertilization?
Options
- A.
The pollen tube will carry one vegetative nucleus and one undivided generative cell, resulting in the complete failure of both syngamy and triple fusion.
- B.
The undivided generative cell will act as a single male gamete and fuse with the egg cell, resulting in syngamy but failing to perform triple fusion.
- C.
The generative cell will undergo normal mitosis, but the resulting male gametes will fail to travel through the pollen tube due to inhibited microtubule tracks.
- D.
The vegetative cell will fail to elongate into a pollen tube because colchicine directly inhibits the actin microfilaments required for tip growth.
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|Vegetative_Cell|Colchicine|Pollen_Tube
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question tests the precise distinction between a 'generative cell' and a 'male gamete', and the specific cytoskeletal targets of colchicine.
A common misconception is that the generative cell itself can act as a gamete (Option B trap) or that colchicine stops all cellular movement/growth by destroying actin (Option D trap).
The student must synthesize cell cycle inhibition (tubulin/spindle failure) with angiosperm embryology (necessity of two distinct male gametes for double fertilization).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Generative Cell Division |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |