which of the following is true for nucleolus?

Options

A. Larger nuclcoli are present in dividing cells.
B. It is a membrane-bound structure.
C. It takes part in spindle formation
D. it is a site for active ribosomal RNA synthesis

Answer

To determine which statements about the nucleolus are true, let's analyze each option step by step:

### Step-by-Step Solution:

1. **Location of Nucleolus**:
- The nucleolus is located within the nucleoplasm of the nucleus. This statement is true.

2. **Size of Nucleolus**:
- The size of the nucleolus varies depending on the cell's ribosomal requirements. Cells that require more ribosomes will have a larger nucleolus. However, the size of the nucleolus does not increase due to cell division. Therefore, the statement about large nucleoli being present in dividing cells is incorrect.

3. **Membrane Structure**:
- The nucleolus is not a membrane-bound structure; it is a non-membrane-bound organelle. This means it does not have a surrounding membrane and is considered a "naked" structure. Thus, the statement claiming that it is a membrane-bound structure is false.

4. **Role in Spindle Formation**:
- The nucleolus does not participate in spindle formation during cell division. Spindle fibers are associated with chromosomes, and the nucleolus has no role in this process. Therefore, this statement is also incorrect.

5. **Function in Ribosomal RNA Synthesis**:
- The nucleolus is indeed the site of active ribosomal RNA (rRNA) synthesis. Ribosomes are composed of rRNA and proteins, and the rRNA is produced in the nucleolus. This statement is true.

### Conclusion:
Based on the analysis:
- The only true statement about the nucleolus is that it is the site of active ribosomal RNA synthesis.