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Question #46007
The Question
During the adaptive radiation of early hominids into high-altitude environments, evolutionary selection favored morphological changes such as increased chest circumference. This adaptation provided the metabolic overhead necessary to support an expanding cranial capacity (encephalization) despite hypoxic conditions. To maximize the absolute volume of air that can be actively exchanged in a single maximal respiratory cycle, which respiratory parameter must have undergone the most significant positive selection, and what is its correct NCERT-aligned representation?
Options
- A.
Vital Capacity; represented as ERV + TV + IRV, because it represents the maximum volume of air a person can breathe in after a forced expiration, dictating the upper limit of active gaseous exchange.
- B.
Total Lung Capacity; represented as VC + RV, because increasing the non-exchangeable residual volume is the primary mechanism to adapt to high-altitude hypoxia.
- C.
Inspiratory Capacity; represented as TV + IRV, because high-altitude adaptation relies exclusively on increasing the volume of air inspired after a normal expiration.
- D.
Functional Residual Capacity; represented as ERV + RV, because an increased resting volume of air is required to support the metabolic demands of encephalization.
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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
Vital Capacity|Residual Volume|Hominid Cranial Capacity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the total anatomical volume of the lungs (Total Lung Capacity) and the maximum functional/exchangeable volume (Vital Capacity).
Common Misconception: Students often assume that high-altitude adaptation strictly requires an increase in Total Lung Capacity (TLC) to 'hold more air'.
However, for active metabolic overhead (like supporting a larger brain during exertion), the exchangeable volume (Vital Capacity) is the critical evolutionary parameter, as Residual Volume (RV) cannot be ventilated.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Breathing and Exchange of Gases - Class 11 |
| Concept | Respiratory Volume vs. Capacity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |