Which of the following statements is correct?

Options

A. Lysosomes play an important role at the time of fertilisation.
B. 80 S-ribosome consists of a large 50 S subunit and small 30 S subunit.
C. Smooth endoplasmic reticulum mainly consists of cisternae whereas rough endoplasmic reticulum mainly consists of tubules and vesicles.
D. All of these

Answer

To solve the question "Which of the following statements is correct?", we will analyze each statement provided in the options.

### Step-by-Step Solution:

1. **Evaluate Statement A**:
- Statement: "Lysosomes play an important role at the time of fertilization."
- Analysis: Lysosomes contain hydrolytic enzymes that help digest the zona pellucida, which is the outer layer of the egg. This is crucial during fertilization as it allows sperm to penetrate the egg.
- Conclusion: This statement is **correct**.

2. **Evaluate Statement B**:
- Statement: "ATS ribosomes consist of a large 50s subunit and a small 30s subunit."
- Analysis: In prokaryotic ribosomes (which are often referred to as ATS or 70S ribosomes), the large subunit is actually 50S and the small subunit is 30S. However, this statement is incorrect because it mislabels the ribosome type. The correct designation for eukaryotic ribosomes is 80S, with 60S and 40S subunits.
- Conclusion: This statement is **incorrect**.

3. **Evaluate Statement C**:
- Statement: "Smooth endoplasmic reticulum mainly consists of cisternae, whereas the rough endoplasmic reticulum mainly consists of tubules and vesicles."
- Analysis: The smooth endoplasmic reticulum (SER) is primarily involved in lipid synthesis and does have a tubular structure, while the rough endoplasmic reticulum (RER) is studded with ribosomes, giving it a rough appearance and is mainly composed of flattened sacs called cisternae. Thus, the statement incorrectly describes the structure of both types of endoplasmic reticulum.
- Conclusion: This statement is **incorrect**.

4. **Evaluate Statement D**:
- Statement: "All of these."
- Analysis: Since we have already established that statements B and C are incorrect, this statement cannot be true.
- Conclusion: This statement is **incorrect**.

### Final Conclusion:
After evaluating all statements, the only correct statement is **Statement A**: "Lysosomes play an important role at the time of fertilization."