Before You Begin
Question #46277
The Question
A researcher isolates a mutant plant of the Solanaceae family (actinomorphic, bisexual, K(5) C(5) A5 G(2)) in which the tapetum completely fails to synthesize sporopollenin precursors. The pollen grains produced are viable and contain normal vegetative and generative cells. If these mutant pollen grains are dusted onto a compatible, receptive stigma of a wild-type plant, fertilization fails to occur. Which of the following best explains this post-pollination barrier?
Options
- A.
The absence of the exine prevents the deposition of tapetum-derived recognition proteins, thereby halting the dynamic chemical dialogue required for pollen-pistil interaction.
- B.
The pollen tube germinates but ruptures within the transmitting tissue of the style because it lacks the osmotic protection normally provided by sporopollenin.
- C.
The generative cell is unable to undergo mitosis to form two male gametes, as this division strictly requires the enzymatic activity of sporopollenin.
- D.
The synoecious nature of the flower triggers an obligate self-incompatibility response, utilizing stigmatic RNases to degrade the unprotected vegetative cell.
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
Solanaceae Floral Formula|Pollen Wall Chemistry|Generative Cell Division
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often reduce sporopollenin's role strictly to physical protection (resistance to heat, acids, and enzymes) and fossilization.
This question tests the synthesis of two NCERT concepts: the tapetum's role in pollen wall formation and the chemical nature of pollen-pistil interaction.
The trap lies in assuming sporopollenin forms the pollen tube (Option B) or acts enzymatically (Option C).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Solanaceae Floral Formula |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |