DNA is present in

Options

A. E.R. and ribosomes
B. ribosomes and chloroplasts
C. ribosomes and mitochondria
D. mitochondria and chloroplastis

Answer

**Step-by-Step Solution:**

1. **Understanding DNA**: DNA stands for deoxyribonucleic acid, which is the hereditary material in almost all living organisms. It carries genetic information essential for growth, development, functioning, and reproduction.

2. **Primary Location of DNA**: The primary location of DNA in eukaryotic cells is the nucleus. The nucleus is a membrane-bound organelle that houses the majority of the cell's genetic material.

3. **Secondary Locations of DNA**: Apart from the nucleus, DNA is also found in certain organelles, specifically mitochondria and chloroplasts. These organelles are involved in energy production and photosynthesis, respectively.

4. **Symbiotic Theory**: The presence of DNA in mitochondria and chloroplasts can be explained by the endosymbiotic theory. This theory suggests that these organelles originated from free-living bacteria that were engulfed by ancestral eukaryotic cells. Over time, these bacteria became integral parts of the cells, leading to the organelles we see today.

5. **Conclusion**: Based on the information, DNA is present in the nucleus, mitochondria, and chloroplasts. Therefore, the correct answer to the question "DNA is present in" is option D: mitochondria and chloroplasts.

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