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Question #45922
The Question
The Kangaroo rat (Dipodomys) of North American deserts rarely drinks water, meeting its hydration needs primarily through internal fat oxidation. Biochemically, why is the oxidation of lipids evolutionarily more advantageous for generating metabolic water compared to the oxidation of carbohydrates?
Options
- A.
Lipids have a higher hydrogen-to-oxygen ratio, yielding more metabolic water per gram when oxygen acts as the terminal electron acceptor in the ETS.
- B.
The oxidation of lipids yields a respiratory quotient (RQ) of 0.7, which directly reduces the evaporative loss of water from the pulmonary surfaces.
- C.
Lipids undergo beta-oxidation in the cytoplasm, releasing free water molecules independently of the mitochondrial electron transport chain.
- D.
Carbohydrates are highly oxidized molecules that consume metabolic water during their conversion to pyruvic acid in glycolysis.
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
Metabolic_Water_Formation|Osmoregulation_in_Aquatic_Adaptations|Kangaroo_Rat_Physiology
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question bridges NCERT Ecology (Kangaroo rat adaptations) with Plant Physiology/Biochemistry (Cellular Respiration).
The common misconception is confusing the Respiratory Quotient (RQ) or ATP yield with the stoichiometric yield of metabolic water.
Students must recognize that metabolic water is a direct product of the hydrogen content of the respiratory substrate being oxidized at the terminal step of the ETS.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Metabolic Water Formation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |