Which is the following hormones attach on a specific receptor site on plasma membrane ?

Options

A. Oestrogen
B. Thyroxine
C. Epinephrine
D. All of these

Answer

To determine which hormone attaches to a specific receptor site on the plasma membrane, we can analyze the options provided:

1. **Understanding Hormone Receptors**:
- Hormones can be classified based on their solubility.
- Water-soluble hormones typically bind to receptors on the plasma membrane, while lipid-soluble hormones usually bind to intracellular receptors.

2. **Analyzing Each Hormone**:
- **Estrogen**: This is a steroid hormone, which is lipid-soluble. It typically binds to intracellular receptors, not to the plasma membrane.
- **Thyroxine**: This is also a lipid-soluble hormone (thyroid hormone) that binds to receptors inside the cell, particularly in the nucleus.
- **Epinephrine**: This is a water-soluble hormone (also known as adrenaline). It binds to specific receptors on the plasma membrane of target cells and works through secondary messengers to exert its effects.
- **All of these**: This option suggests that all the hormones listed bind to plasma membrane receptors, which is not accurate based on the analysis.

3. **Conclusion**:
- Based on the analysis, the hormone that attaches to a specific receptor site on the plasma membrane is **epinephrine**.

Thus, the correct answer is **epinephrine**.

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