Viruses cannot multiply of their own or be grown in vitro on artificial medium because they

Options

A. are dead
B. do not have sex organs and gametes
C. lack genetic material
D. lack cellular machinery to use their own genetic material

Explanation

**Step-by-Step Solution:**

1. **Definition of Viruses**: Viruses are biological agents that are classified as obligate intracellular parasites. This means they cannot live or reproduce outside of a host cell.

2. **Structure of Viruses**: Viruses consist of genetic material (either DNA or RNA) surrounded by a protein coat known as a capsid. This structure is essential for protecting the genetic material.

3. **Lack of Cellular Machinery**: Unlike living cells, viruses do not possess the necessary cellular machinery (like ribosomes, enzymes, etc.) required for metabolic processes and reproduction. They are unable to perform functions independently.

4. **Reproduction Process**: To reproduce, viruses must enter a host cell. Once inside, they hijack the host's cellular machinery to replicate their genetic material and produce new virus particles.

5. **Inability to Grow in Artificial Medium**: In vitro (artificial medium) does not provide the cellular machinery that viruses need. Since they cannot reproduce or multiply on their own, they cannot grow in an artificial environment.

6. **Conclusion**: Therefore, the statement that viruses cannot multiply on their own or be grown in vitro on artificial medium is because they lack the necessary cellular machinery to utilize their genetic material independently.

**Final Answer**: Viruses cannot multiply on their own or be grown in vitro on artificial medium because they lack cellular machinery.

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