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Question #46700
The Question
A frog (Rana tigrina) is exposed to a desiccating environment, triggering a defensive physiological response where its epidermis thickens with keratin-like proteins to minimize water loss. Despite having functional lungs, the frog rapidly develops severe respiratory acidosis. Which of the following best explains this physiological collapse?
Options
- A.
Increased diffusion distance across the integument drastically lowers the rate of CO2 elimination per Fick's Law, as amphibian lungs are insufficiently alveolated to handle total gas exchange.
- B.
Keratinization induces a leftward shift in the oxygen dissociation curve due to localized hypoxia, preventing adequate O2 delivery to the tissues.
- C.
The loss of cutaneous moisture directly inhibits the buccal pump mechanism, completely halting both pulmonary and buccopharyngeal respiration.
- D.
The thickened epidermis increases the partial pressure of O2 in the subcutaneous capillaries, leading to oxygen toxicity and subsequent metabolic alkalosis.
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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
Frog Integumentary Respiration|Osmoregulation in Aquatic Adaptations|Partial Pressure Gradient Logic
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that because adult frogs possess lungs, pulmonary respiration can fully compensate for the loss of cutaneous respiration.
The trap lies in failing to recognize that amphibian lungs are structurally primitive (poorly alveolated) and that cutaneous gas exchange is absolutely mandatory for sufficient CO2 elimination to prevent fatal acidosis.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Structural Organisation in Animals - Class 11 |
| Concept | Frog Integumentary Respiration |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |