Which one of the following structures is an organelle within an organelle
" " Or
Which of the following cell organelle lacks DNA and bounding membrane

Options

A. Peroxisome
B. ER
C. Mesosome
D. Ribosome

Explanation

To solve the question, we need to identify which of the given cell organelles is both an organelle within an organelle and lacks DNA and a bounding membrane. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Question
The question asks for an organelle that is found within another organelle and also lacks DNA and a bounding membrane. This means we are looking for a specific type of organelle that meets all these criteria.

### Step 2: Analyze the Options
We will evaluate each option provided to determine if it meets the criteria.

1. **Peroxisomes**:
- They are not organelles within organelles; they are free organelles in the cytoplasm.
- They lack DNA.
- They are membrane-bound organelles.
- **Conclusion**: Not the correct answer.

2. **Endoplasmic Reticulum (ER)**:
- It is not an organelle within an organelle; it exists freely in the cytoplasm.
- It lacks DNA.
- It is a membrane-bound organelle.
- **Conclusion**: Not the correct answer.

3. **Mesosomes**:
- They are found in prokaryotic cells and are not organelles within organelles.
- They contain DNA (single chromosome).
- They are membrane-bound.
- **Conclusion**: Not the correct answer.

4. **Ribosomes**:
- Ribosomes can be considered organelles within organelles because they can be found free in the cytoplasm or bound to the endoplasmic reticulum or other organelles.
- They lack their own DNA.
- They are not membrane-bound; they consist of two subunits.
- **Conclusion**: This is the correct answer.

### Step 3: Final Answer
Based on the analysis, the correct answer is **Ribosomes**. They are the organelle that is within another organelle, lacks DNA, and does not have a bounding membrane.