Electron microscope has revealed the presence of or Which among the following can be seen only under electron microscope

Options

A. Ribosomes
B. Chromosomes
C. Chloroplast
D. Leucoplast

Answer

To solve the question regarding which among the following can be seen only under an electron microscope, we will analyze each option based on their visibility under different types of microscopes.

### Step-by-Step Solution:

1. **Understand the Function of an Electron Microscope**:
- An electron microscope uses a beam of electrons to create an image of the specimen. It has a much higher magnification power compared to a light microscope, typically ranging from 250,000 to 400,000 times.

2. **Evaluate the Options**:
- **Ribosomes**: These are small cellular organelles with a diameter of about 23 nanometers. Due to their small size, they cannot be seen using a light microscope but can be visualized using an electron microscope.
- **Chromosomes**: These structures are larger than ribosomes and can be observed under a light microscope during cell division when they are condensed.
- **Chloroplasts**: These organelles are relatively large and can also be seen under a light microscope.
- **Leucoplasts**: Similar to chloroplasts, leucoplasts are larger organelles and can be observed with a light microscope.

3. **Conclusion**:
- Among the given options, ribosomes are the only structures that can be seen exclusively under an electron microscope due to their extremely small size.

### Final Answer:
The correct answer is **Ribosomes**.

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