The endoskeleton of cell is made up of

Options

A. ER
B. cytoplasm
C. nucleus
D. ribosomes

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the composition of the endoskeleton of a cell. The term "endoskeleton" refers to the internal support structure of the cell.

2. **Identifying Options**: The options provided are:
- a) Endoplasmic Reticulum (ER)
- b) Cytoplasm
- c) Nucleus
- d) Ribosomes

3. **Defining Endoskeleton**: The endoskeleton in a cell context refers to the internal membrane system that provides structural support, similar to how a skeleton supports a body.

4. **Analyzing Each Option**:
- **Endoplasmic Reticulum (ER)**: The ER is a network of membranes involved in protein and lipid synthesis. It is a significant component of the endoskeleton as it provides structural support and is part of the internal membrane system.
- **Cytoplasm**: This is the gel-like substance within the cell where organelles are suspended. It does not constitute the endoskeleton.
- **Nucleus**: The nucleus is the control center of the cell containing genetic material. While it is vital for cell function, it does not form part of the endoskeleton.
- **Ribosomes**: These are the sites of protein synthesis but are not involved in providing structural support.

5. **Conclusion**: Based on the analysis, the endoskeleton of the cell is primarily made up of the Endoplasmic Reticulum (ER). Therefore, the correct answer is **a) Endoplasmic Reticulum (ER)**.

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