Which among the following can be seen only under electron microscope?
(a) Chloroplast
(b) Ribosome
(c) Leucoplast
(d) Nucleus

Options

A. Chloroplast
B. Ribosome
C. Leucoplast
D. Nucleus

Answer

To determine which among the given options can be seen only under an electron microscope, we need to analyze each option based on the capabilities of light microscopes versus electron microscopes.

1. **Understanding Electron Microscopes**:
- Electron microscopes provide much higher resolution than light microscopes. They can visualize structures at the molecular and atomic levels, which are not visible under light microscopes.

2. **Analyzing the Options**:
- **(a) Chloroplast**: Chloroplasts are organelles found in plant cells and can be observed under a light microscope due to their relatively large size.
- **(b) Ribosome**: Ribosomes are very small structures (approximately 20-30 nm) and are typically only visible under an electron microscope.
- **(c) Leucoplast**: Leucoplasts are also organelles found in plant cells and can be seen under a light microscope.
- **(d) Nucleus**: The nucleus is a large organelle that can be easily observed under a light microscope.

3. **Conclusion**:
- Among the given options, ribosomes are the only structures that can only be seen under an electron microscope due to their small size. Therefore, the correct answer is **(b) Ribosome**.