Which one of the following is not a plastid ?

Options

A. Aleuroplast
B. Chromoplast
C. Chloroplast
D. Aleurone

Answer

To solve the question "Which one of the following is not a plastid?", we will analyze each of the given options to determine which one does not belong to the category of plastids.

### Step-by-Step Solution:

1. **Understanding Plastids**:
- Plastids are organelles found in the cells of plants and algae. They are involved in the manufacture and storage of important chemical compounds used by autotrophic organisms. Common types of plastids include chloroplasts, chromoplasts, and leucoplasts.

2. **Analyzing Option 1 - Alluroplast**:
- Alluroplast is a type of leucoplast, which is a plastid specialized for the storage of proteins. Therefore, alluroplast is indeed a plastid.

3. **Analyzing Option 2 - Chromoplast**:
- Chromoplasts are plastids that synthesize and store pigments, such as carotene (orange), xanthophyll (yellow), and various red pigments. Thus, chromoplasts are also plastids.

4. **Analyzing Option 3 - Chloroplast**:
- Chloroplasts are the most well-known type of plastid, containing chlorophyll, the green pigment essential for photosynthesis. Therefore, chloroplasts are plastids as well.

5. **Analyzing Option 4 - Aluron**:
- Aluron refers to protein granules found in seeds, but it is not classified as a plastid. Instead, it is a storage form of proteins in plant seeds. Hence, Aluron is not a plastid.

6. **Conclusion**:
- After analyzing all the options, we find that the correct answer to the question "Which one of the following is not a plastid?" is **Option 4 - Aluron**.

### Final Answer:
**Option 4 - Aluron is not a plastid.**