(a) State the location of haemoglobin in human blood and mention one structural feature that makes it suitable for oxygen transport.
(b) Why is haemoglobin considered essential for the survival of large multicellular animals?
Generated by claude-sonnet-4-6 · 2026-06-26 00:59 · grounding rag
Model Answer
(a) Haemoglobin is found inside the red blood corpuscles (RBCs) in blood. It has a high affinity for oxygen, which allows it to bind oxygen efficiently in the lungs and release it to body tissues.
(b) In large multicellular organisms, not all cells are in direct contact with the environment, so oxygen cannot reach every cell by simple diffusion. Haemoglobin greatly increases the oxygen-carrying capacity of blood, ensuring adequate oxygen supply to all cells for energy (ATP) production. Without it, the circulatory system alone could not deliver sufficient oxygen to sustain life.
Source: Chapter 5, Section 5.4.1 Transportation in Human Beings
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Explanation
- (a) The key points examiners expect: location = inside RBCs (not just "in blood"), and one structural/functional feature — high affinity for oxygen is the standard answer. "Haemoglobin is a red pigment" alone won't fetch the mark; you must link the feature to oxygen transport.
- (b) The logic chain to show: large body → cells not in contact with environment → diffusion insufficient → haemoglobin essential to carry enough O₂. This directly mirrors the Class IX/X textbook reasoning about why specialised transport is needed in multicellular organisms.
- Avoid writing "haemoglobin is in plasma" — that is factually wrong; it is inside RBCs.