Carbamino-Hemoglobin Formation & CO₂ Transport — NEET Biology
✅ Asked in NEET 2024Assertion (A): About 20–25% of CO₂ is transported as carbamino-haemoglobin. Reason (R): This is facilitated by high pCO₂ and low pO₂ in tissues. NEET 2024
Assertion (A): About 20–25% of CO₂ is transported as carbamino-haemoglobin. Reason (R): This is facilitated by high pCO₂ and low pO₂ in tissues. NEET 2024
Answer & NCERT explanation
Correct answer: A — Both A and R are true and R is the correct explanation of A
About 20-25% of CO₂ is indeed transported as carbamino-haemoglobin, formed when CO₂ binds to amino groups of globin chains. High pCO₂ and low pO₂ in tissues favor this formation because deoxygenated haemoglobin has greater affinity for CO₂ (Haldane effect). These conditions promote CO₂ binding to haemoglobin, making R the correct explanation of A.
Read more NCERT concept on the PYQ
CO₂ is carried by haemoglobin as carbamino-haemoglobin (about 20-25 per cent). This binding is related to the partial pressure of CO₂. pO₂ is a major factor which could affect this binding. When pCO₂ is high and pO₂ is low as in the tissues, more binding of carbon dioxide occurs whereas, when the pCO₂ is low and pO₂ is high as in the alveoli, dissociation
NTA tests the mechanism of CO₂ transport as carbamino-hemoglobin (20-25%), which forms when hemoglobin binds CO₂ directly. The key concept is that this binding increases in tissues (high pCO₂, low pO₂) and decreases in lungs (low pCO₂, high pO₂). Students often confuse carbamino-hemoglobin with oxyhemoglobin or forget that partial pressures of both O₂ and CO₂ regulate this binding. Remember: pO₂ competes with pCO₂—when oxygen is high, CO₂ dissociates; when CO₂ is high and oxygen is low, more carbamino-hemoglobin forms. This dual-pressure mechanism is crucial for efficient gas exchange.
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