Consider the following statements
A. In prokaryotic cells a special membranous structure formed by the extension of the plasma membrane into the cell is known as polysome
B. The smooth endoplasmic reticulum is the major site for synthesis of glycoproteins
C. RuBisCo is the most abundant protein in the whole of biospshere
D. Mitochondria, chloroplasts and peroxisomes are not considered as part of endomembrane system
Of the above statements

Options

A. c and d alone are correct
B. a and b alone are correct
C. a and c alone are correct
D. a and d are wrong

Answer

To evaluate the given statements regarding cellular structures and functions, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A: In prokaryotic cells, a special membranous structure formed by the extension of the plasma membrane into the cell is known as polysome.**
- **Analysis**: This statement is incorrect. In prokaryotic cells, the structure formed by the extension of the plasma membrane is called **mesosomes**, not polysomes. Polysomes refer to aggregates of ribosomes that are involved in protein synthesis.
- **Conclusion**: **Statement A is false.**

2. **Statement B: The smooth endoplasmic reticulum is the major site for synthesis of glycoproteins.**
- **Analysis**: This statement is also incorrect. The **rough endoplasmic reticulum (RER)** is primarily responsible for the synthesis of glycoproteins, as it is studded with ribosomes. The smooth endoplasmic reticulum (SER) is mainly involved in lipid synthesis and metabolism.
- **Conclusion**: **Statement B is false.**

3. **Statement C: RuBisCo is the most abundant protein in the whole of the biosphere.**
- **Analysis**: This statement is correct. **RuBisCo** (ribulose-1,5-bisphosphate carboxylase/oxygenase) is indeed the most abundant protein on Earth, as it plays a crucial role in the process of photosynthesis by fixing carbon dioxide in the Calvin cycle.
- **Conclusion**: **Statement C is true.**

4. **Statement D: Mitochondria, chloroplasts, and peroxisomes are not considered as part of the endomembrane system.**
- **Analysis**: This statement is correct. The endomembrane system includes organelles such as the endoplasmic reticulum, Golgi apparatus, and lysosomes, but does not include mitochondria, chloroplasts, or peroxisomes.
- **Conclusion**: **Statement D is true.**

### Final Evaluation:
- **True Statements**: C and D
- **False Statements**: A and B

### Final Answer:
Of the above statements, **C and D are correct**.

---