The some peptide hormone will show variation in response to different cells because

Options

A. different target cells have different sets of genes
B. a target cell's response is determined by the components of its signal transduction pathways
C. the circulatory system regulates response to hormone by routing the hormone to specific targets
D. the hormone is chemically altered in different ways as it travels through the circulatory system

Answer

To solve the question regarding why some peptide hormones show variation in response to different cells, we can analyze the options provided in the context of how hormones interact with target cells.

### Step-by-Step Solution:

1. **Understanding Peptide Hormones**: Peptide hormones are signaling molecules that bind to specific receptors on target cells. Their effects can vary based on the type of cell they interact with.

2. **Different Target Cells Have Different Receptors**: Each type of target cell has a unique set of receptors. The binding of a hormone to its receptor initiates a signal transduction pathway that can lead to different cellular responses. Therefore, the variation in response can be attributed to the presence of different receptors on different cells.

3. **Signal Transduction Pathways**: The response of a target cell to a hormone is determined by the components of its signal transduction pathway. Different cells may have different proteins and enzymes involved in this pathway, leading to varied responses even when the same hormone is present.

4. **Circulatory System Routing**: While the circulatory system does play a role in delivering hormones to target cells, it does not account for the variation in response. The specificity of the response is more about the cell's internal mechanisms rather than the routing of the hormone.

5. **Chemical Alteration of Hormones**: Hormones may undergo modifications in the body, but this is not the primary reason for the variation in response among different cells. The fundamental reason lies in the receptor and signaling pathways.

### Conclusion:
The correct answer is that the variation in response to peptide hormones among different cells is primarily due to the fact that **a target cell's response is determined by the components of its signal transduction pathway**.