Iodine is an important constituent of

Options

A. salt
B. food
C. thyroxine
D. haemoglobin

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks about the important constituent of iodine.

2. **Understand the Role of Iodine**: Iodine is a crucial element in the human body, particularly in the production of thyroid hormones.

3. **Identify the Thyroid Hormones**: The two primary thyroid hormones that require iodine for their synthesis are:
- Thyroxine (T4)
- Triiodothyronine (T3)

4. **Explain the Synthesis of Thyroid Hormones**:
- Thyroid hormones are synthesized in the thyroid gland.
- They are formed from the amino acid tyrosine and require iodine for their structure.

5. **Mention the Storage of Thyroid Hormones**: The thyroid hormones are stored in the form of a protein called thyroglobulin before being released into the bloodstream.

6. **Dietary Source of Iodine**: Iodine is primarily obtained through the diet, often added to table salt to ensure adequate intake.

7. **Conclusion**: Therefore, iodine is an important constituent of thyroxine (T4) and triiodothyronine (T3), which are essential for the proper functioning of the thyroid gland.

### Final Answer:
Iodine is an important constituent of thyroxine (T4) and triiodothyronine (T3), which are hormones produced by the thyroid gland.

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