Topics:
Animal Physiology, Animal Refresher
Haemoglobin Forms and Their Colours
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Question (English)
Which of the following pair(s) of haemoglobin form and its colour is/are correctly matched?
- Oxyhemoglobin: bright red colour only
- Carboxyhemoglobin: bright cherry red colour only
- Nitrate poisoning: chocolate brown colour only
- All three pairs are correctly matched ✓ Correct
Explanation:
Correct Answer: All the above — all three pairs are correctly matched
Forms of Haemoglobin and Their Colours
| Form | Colour | How it Forms |
|---|---|---|
| Oxyhemoglobin (HbO₂) | Bright red | Hb + O₂ (oxygenation — Fe remains Fe²⁺) |
| Carboxyhemoglobin (HbCO) | Bright cherry red | Hb + CO (carbon monoxide poisoning) |
| Methemoglobin (MetHb) | Chocolate brown | Oxidation of Fe²⁺ → Fe³⁺ (e.g., nitrate/chlorate poisoning) |
| Carbaminohemoglobin (HbCO₂) | Dark red (deoxygenated) | Hb + CO₂ (CO₂ transport) |
Important Distinctions
- Oxygenation vs. Oxidation: Oxygenation (Hb → HbO₂) keeps Fe²⁺; Oxidation (Hb → MetHb) converts Fe²⁺ to Fe³⁺.
- MetHb is the true oxidation product of Hb — cannot carry O₂.
- CO has ~250× higher affinity for Hb than O₂ → dangerous in CO poisoning.
- Normal blood levels of MetHb: <1%. Methemoglobinemia (>10%) causes cyanosis.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
