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Question #46282
The Question
A plant characterized by the floral formula Br, Actinomorphic, Bisexual, P(3+3), A3+3, G(3) is grown in a nutrient-deficient hydroponic medium during its reproductive phase. The botanist observes severe necrosis in the newly forming floral primordia, preventing the differentiation of the perianth. However, the older, mature leaves remain completely healthy and green. Which of the following correctly identifies the deficient element and the physiological basis for this specific symptom distribution?
Options
- A.
Magnesium; it is a mobile element required for perianth pigmentation, and its deficiency causes immediate necrosis in young tissues.
- B.
Calcium; it is a phloem-immobile element essential for synthesizing the middle lamella during cytokinesis in the rapidly dividing floral meristem.
- C.
Nitrogen; it is a highly mobile element that gets rapidly translocated to older leaves, starving the floral primordia of essential amino acids.
- D.
Phosphorus; it is an immobile element that acts as a constituent of cell membranes, causing structural collapse in young floral tissues.
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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
Liliaceae|Nutrient Immobility|Floral Anatomy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Angiosperm Morphology (Liliaceae floral formula) with Plant Physiology (Mineral mobility and deficiency symptoms).
The trap relies on students confusing the mobility of elements; N, P, and Mg are mobile (symptoms in old leaves), while Ca is immobile (symptoms in young meristems).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Liliaceae Floral Formula |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |