(a) granular structure
(b) first observed under the electron microscope as dense particles by George Palade ( c ) composed of RNA and proteins
not surrounded by any membrane
Above given statements are true for which cell organelle?

Options

A. Nucleolus
B. Ribosomes
C. Cristae
D. Chloroplast

Answer

### Step-by-Step Solution:

1. **Identify the Characteristics**: The question provides several characteristics of a cell organelle:
- Granular structure
- First observed as dense particles by George Palade
- Composed of RNA and proteins
- Not surrounded by any membrane

2. **Analyze Each Characteristic**:
- **Granular Structure**: This suggests a structure that appears grainy or composed of small particles, which is typical of ribosomes.
- **Observation by George Palade**: George Palade is known for his work on ribosomes and was instrumental in their discovery using electron microscopy.
- **Composition of RNA and Proteins**: Ribosomes are indeed made up of ribosomal RNA (rRNA) and proteins, which aligns with this characteristic.
- **Not Surrounded by Any Membrane**: Ribosomes are unique in that they are not enclosed by a membrane, distinguishing them from many other organelles.

3. **Conclusion**: Based on the analysis of the characteristics provided, the organelle that fits all the descriptions is the **ribosome**.

### Final Answer:
The cell organelle described by the statements is the **ribosome**.

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