Thyroidectomised tadpole will metamorphose by administration of

Options

A. Pituitary extract
B. Thyroxine
C. TSH
D. Iodine.

Answer

To answer the question, "Thyroidectomised tadpole will metamorphose by administration of," we need to follow these steps:

### Step-by-Step Solution:

1. **Understand Thyroidectomy**:
- Thyroidectomy refers to the surgical removal of the thyroid gland. In the context of a tadpole, this means that the gland responsible for producing certain hormones is no longer present.

2. **Define Metamorphosis**:
- Metamorphosis is the biological process by which an organism transforms from its larval stage into its adult form. In frogs, this process is crucial for their development.

3. **Role of Thyroid Hormones**:
- The thyroid gland produces hormones, particularly thyroxine (T4), which are essential for regulating metabolism and promoting growth. In tadpoles, thyroxine is critical for initiating and regulating the metamorphosis process.

4. **Effects of Thyroidectomy**:
- When the thyroid gland is removed, the tadpole cannot produce thyroxine. Without this hormone, the normal process of metamorphosis is halted, and the tadpole will not develop into its adult form.

5. **Administering Thyroxine**:
- To induce metamorphosis in a thyroidectomised tadpole, it is necessary to provide an external source of thyroxine. This can be done by administering ready-made thyroxine hormone directly to the tadpole.

6. **Conclusion**:
- Therefore, the correct answer to the question is that a thyroidectomised tadpole will metamorphose by the administration of **thyroxine**.