Haemocyanin , the blue colour respiratory pigment of molluscans blood contains

Options

A. magnesium as the central metal ion.
B. copper as the central metal ion.
C. iron as the central metal ion.
D. manganese as the central metal ion.

Answer

**Step-by-Step Solution:**

1. **Understanding Hemocyanin**: Hemocyanin is a respiratory pigment found in the blood of certain invertebrates, particularly mollusks and some arthropods. It is responsible for transporting oxygen in the blood.

2. **Color of Hemocyanin**: The pigment is characterized by its blue color, which is a key feature that distinguishes it from other respiratory pigments like hemoglobin, which is red.

3. **Composition of Hemocyanin**: The primary component of hemocyanin is copper. In hemocyanin, copper ions are present in the active site where oxygen binding occurs.

4. **Mechanism of Oxygen Binding**: Hemocyanin contains two copper ions that can bind to a single molecule of oxygen. This binding is what enables the transport of oxygen throughout the organism's body.

5. **Conclusion**: Given the information, the correct answer to the question is that hemocyanin contains copper as its central metal ion.

**Final Answer**: Hemocyanin, the blue color respiratory pigment of molluscan blood, contains copper.

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