Before You Begin

Question #46165

Difficulty: 8/10 | 🟢 Free

The Question

Chordates are characterized by the presence of pharyngeal gill slits at some stage of their life cycle. During the evolutionary transition from aquatic to terrestrial habitats, both morphological and physiological adaptations occurred. Which of the following correctly correlates the developmental fate of the embryonic pharyngeal apparatus in mammals with their relative Oxygen-Hemoglobin ( $O_2-Hb$ ) dissociation curve dynamics compared to aquatic ancestors?

Options

A.
The first pharyngeal pouch develops into the Eustachian tube, and the mammalian $O_2-Hb$ curve is relatively right-shifted to facilitate efficient oxygen unloading in tissues.
B.
The pharyngeal clefts develop into the larynx and trachea, and the mammalian $O_2-Hb$ curve is relatively left-shifted to maximize oxygen loading from the atmosphere.
C.
The embryonic pharyngeal slits are modified into pulmonary alveoli, and the $O_2-Hb$ curve becomes hyperbolic to adapt to the higher $pO_2$ of air.
D.
The first pharyngeal pouch forms the external auditory meatus, and the mammalian $O_2-Hb$ curve is relatively right-shifted due to the absence of the Bohr effect.

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Comparative_Analysis

Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.

Concepts Behind This Question

Pharyngeal_gill_slits|Oxygen-Hemoglobin_Dissociation_Curve|Chordata

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: Integrating evolutionary embryology (fate of pharyngeal pouches) with respiratory physiology (comparative hemoglobin affinity).

Students often confuse the origin of the respiratory tract with pharyngeal slits and mistakenly assume terrestrial animals need a 'left-shifted' curve to breathe air, failing to realize that high atmospheric $pO_2$ allows for a right-shifted curve optimized for tissue unloading.

Furthermore, it tests the micro-terminology distinction between pharyngeal 'pouches' (endoderm) and 'clefts' (ectoderm).

Quick Facts About This Question

Question Information

Subject	Biology
Chapter	Animal Kingdom - Class 11
Concept	Chordata Fundamental Trio
Difficulty	8
Cognitive Load	5
Target Solve Time	120 sec
Access	Free