Choose the incorrect match .

Options

A. Primary messenger : Calcium ion
B. Insulin : Peptide hormone
C. Erythropoietin : Formation of RBC
D. Aldosterone : Steroid

Answer

To solve the question, we need to analyze each of the given matches and determine which one is incorrect.

### Step-by-Step Solution:

1. **Understanding Primary and Secondary Messengers**:
- Primary messengers are hormones that bind to receptors on the cell membrane and initiate a response. They do not enter the cell.
- Secondary messengers are molecules that relay signals received at receptors on the cell surface to target molecules inside the cell.

2. **Analyzing the First Match**:
- The first match is "Primary messenger - Calcium ion".
- Calcium ions are known to act as secondary messengers in various signaling pathways. Therefore, this match is incorrect.

3. **Analyzing the Second Match**:
- The second match is "Insulin Hormone - Peptide Hormone which reduces the level of Glucose in blood".
- Insulin is indeed a peptide hormone and its primary function is to lower blood glucose levels. This match is correct.

4. **Analyzing the Third Match**:
- The third match is "Erythropoietin - Peptide hormone responsible for erythropoiesis".
- Erythropoietin is secreted by the kidneys and stimulates the production of red blood cells (erythropoiesis). This match is also correct.

5. **Analyzing the Fourth Match**:
- The fourth match is "Aldosterone - Mineralocorticoid hormone that retains sodium ion".
- Aldosterone is a steroid hormone produced by the adrenal glands and is indeed responsible for sodium retention. This match is correct.

6. **Conclusion**:
- The only incorrect match is the first one: "Primary messenger - Calcium ion".

### Final Answer:
The incorrect match is "Primary messenger - Calcium ion".