alleryMost CO₂ is transported in the blood as
Adissolved CO₂ in plasma
Bcarbamino-haemoglobin in red cells
Ccarbonic acid (H₂CO₃) in plasma
Dbicarbonate ions (HCO₃⁻) in plasma
Answer & Solution
Correct answer: D. bicarbonate ions (HCO₃⁻) in plasma
About 70% of CO₂ is carried as bicarbonate (HCO₃⁻) dissolved in plasma.
Inside RBCs, carbonic anhydrase converts CO₂ + H₂O to H₂CO₃, which dissociates to H⁺ + HCO₃⁻.
HCO₃⁻ leaves the cell (chloride shift).
Carbamino-Hb carries 20-25%; dissolved CO₂ in plasma is only ~7%.
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