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Question #46191
The Question
The evolutionary transition of Aves towards powered flight involved extreme skeletal modifications, notably the pneumatization of long bones. Which of the following statements regarding the physiological and structural trade-offs of this adaptation is INCORRECT?
Options
- A.
The reduction of red bone marrow in pneumatic long bones is compensated by the Bursa of Fabricius, which serves as the primary lymphoid organ for T-lymphocyte maturation.
- B.
The pneumatization of bones reduces overall specific gravity, while the fusion of posterior vertebrae into a synsacrum provides the rigid structural axis required for flight.
- C.
Despite the extreme modification of the endoskeleton for flight, the embryonic notochord is still entirely replaced by a bony vertebral column in adult birds.
- D.
The air sacs connected to the lungs extend into the cavities of these pneumatic bones, supplementing continuous oxygenation and aiding in internal temperature regulation.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Evolutionary Notochord Progression|Aves Pneumatic Bones|Bipedalism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot & Functional Overlap Trap: Students easily recall that birds have pneumatic bones and possess a unique organ called the Bursa of Fabricius.
The trap exploits the functional overlap between B-cells and T-cells.
By stating the Bursa is for T-lymphocyte maturation, it tests whether the student truly understands the origin of immunological nomenclature (B-cells = Bursa-derived in birds / Bone marrow-derived in mammals; T-cells = Thymus-derived in both) rather than just recognizing biological buzzwords.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Aves Pneumatic Bones |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |