Exchange & Transport of Gases — NEET Biology MCQs with Solutions
Free NEET Biology Exchange & Transport of Gases MCQs with step-by-step solutions (6 questions). Part of Breathing and Exchange of Gases. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Exchange & Transport of Gases · easy · theory
The gas transported mainly as oxyhaemoglobin in the blood is:
A. Carbon monoxide
B. Carbon dioxide
C. Oxygen ✓ Correct
D. Nitrogen
Solution: O₂ binds reversibly to the iron of haemoglobin, forming oxyhaemoglobin (about 97% of O₂ transport).
Q2 — Exchange & Transport of Gases · easy · theory
The major form (about 70%) in which CO₂ is transported in the blood is:
A. As carbaminohaemoglobin
B. Dissolved in plasma
C. As carbonic acid gas
D. As bicarbonate ions (HCO₃⁻) ✓ Correct
Solution: Around 70% of CO₂ travels as bicarbonate; ~20–25% as carbamino-haemoglobin and ~7% dissolved.
Q3 — Exchange & Transport of Gases · medium · theory
Gas exchange across the alveoli and tissues occurs by:
A. Facilitated diffusion via carriers
B. Bulk flow only
C. Simple diffusion based on partial pressure gradients ✓ Correct
D. Active transport using ATP
Solution: O₂ and CO₂ diffuse along their partial pressure (pO₂/pCO₂) gradients — no energy is spent.
Q4 — Exchange & Transport of Gases · medium · theory
The enzyme in red blood cells that catalyses the interconversion of CO₂ and water to carbonic acid/bicarbonate is:
A. Carbonic anhydrase ✓ Correct
B. Pepsin
C. Amylase
D. Catalase
Solution: Carbonic anhydrase (in RBCs) speeds CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻, aiding CO₂ transport.
Q5 — Exchange & Transport of Gases · hard · theory
The sigmoid oxygen-haemoglobin dissociation curve shifts to the RIGHT (favouring O₂ unloading) when there is:
A. Low pCO₂ and high pH
B. Low temperature only
C. High pCO₂, high H⁺ (low pH) and higher temperature ✓ Correct
D. High pO₂ only
Solution: The Bohr effect: high CO₂, low pH, high temperature (as in active tissues) shift the curve right, releasing more O₂.
Q6 — Exchange & Transport of Gases · hard · theory
In the alveoli, factors favourable for the formation of oxyhaemoglobin are:
A. Low pO₂ and high pCO₂
B. Low pO₂ only
C. High temperature and high H⁺
D. High pO₂, low pCO₂, low H⁺ and lower temperature ✓ Correct
Solution: At the alveoli (high pO₂, low pCO₂/H⁺), haemoglobin binds O₂; in tissues (opposite conditions) it releases O₂.