RNAi is a method of cellular defence in

Options

A. 1) In majority of eukaryotes
B. 2)in all prokaryotes
C. 3)In G.M crops only
D. 4)In all eukaryotic organisms

Answer

**Step-by-Step Solution:**

1. **Understanding RNA and RNAi:**
- RNA stands for ribonucleic acid, which is a type of nucleic acid present in all living cells.
- RNA interference (RNAi) is a biological process where small RNA molecules inhibit gene expression or translation.

2. **Function of RNAi:**
- RNAi involves small pieces of RNA that can bind to messenger RNA (mRNA) and prevent the translation of proteins.
- This process is crucial for regulating protein synthesis and plays a role in cellular defense mechanisms.

3. **Types of RNA involved in RNAi:**
- There are two main types of small RNA involved in RNA interference:
- Small interfering RNA (siRNA)
- Micro RNA (miRNA)

4. **Role of RNAi in Cellular Defense:**
- RNAi acts as a defense mechanism against viruses by targeting and degrading viral mRNA, thereby preventing the production of viral proteins.

5. **Identifying the Correct Option:**
- The question asks in which organisms RNAi serves as a method of cellular defense.
- The options provided are:
- A) Majority of eukaryotes
- B) All prokaryotes
- C) GM crops only
- D) All eukaryotic organisms
- Since RNAi is a method of cellular defense that is present in all eukaryotic organisms, the correct answer is option D.

**Final Answer:**
RNAi is a method of cellular defense in **all eukaryotic organisms** (Option D).

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