Before You Begin
Question #46818
The Question
A temperate dicot tree experiences a severe mid-summer drought. According to Blackman's Law of Limiting Factors, stomatal closure makes internal CO2 a limiting factor, drastically reducing photosynthetic yield. If optimal conditions resume a month later and persist until autumn, what will be the anatomical consequence on the secondary xylem deposited during that year?
Options
- A.
The vascular cambium will produce a continuous band of wide-cavity vessels, as the subsequent optimal conditions compensate for the drought.
- B.
A band of narrow-cavity vessels and tracheids will be sandwiched between two bands of wider vessels, forming a 'false annual ring'.
- C.
The cambium will permanently lose its activity for the season, resulting in the complete absence of late wood.
- D.
The newly formed secondary xylem will immediately develop tyloses, converting the entire year's growth into heartwood.
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
Spring Wood|Autumn Wood|RUBISCO|Limiting Factors
Why This Question Is Tricky
Common Mistakes
The Conceptual Pivot lies in moving beyond the rote memorization of 'Spring = wide vessels' and 'Autumn = narrow vessels'.
Students must synthesize Plant Anatomy with Plant Physiology, recognizing that cambial activity is not magically dictated by the calendar, but is a direct function of photosynthetic output.
When an environmental stressor invokes the Law of Limiting Factors, the resulting drop in photosynthate forces a premature, temporary shift to narrow-vessel deposition, creating a false ring.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Spring vs Autumn Wood |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |