In the light of recent classification of living organisms into three domains of life (bacteria, archea and eukarya), which one of the following statements is true about archaea

Options

A. Archaea completely differ from prokaryotes
B. Archaea resemble eukarya in all respects
C. Archaea have some novel features that are absent in other prokaryotes and eukaryotes
D. Archaea completely differ from both prokaryotes and eukaryotes

Answer

To determine which statement is true about Archaea in the context of the three domains of life (Bacteria, Archaea, and Eukarya), we can analyze the characteristics of Archaea compared to Bacteria and Eukarya.

### Step-by-Step Solution:

1. **Understanding the Domains**:
- The three domains of life are Bacteria, Archaea, and Eukarya.
- Bacteria and Archaea are both classified as prokaryotes, meaning they lack a nucleus and membrane-bound organelles. Eukarya includes organisms that have a nucleus and organelles.

2. **Characteristics of Archaea**:
- Archaea are distinct from Bacteria in several ways. They can thrive in extreme environments (extremophiles) such as high temperatures, high salinity, or extreme pH levels.
- They have unique biochemical pathways and structures, such as their cell membrane composition, which differs from that of Bacteria.

3. **Examining the Statements**:
- **Statement 1**: "Archaea completely differs from prokaryotes." This is false because Archaea are indeed prokaryotes.
- **Statement 2**: "Archaea resembles eukarya in all respects." This is also false; while Archaea share some similarities with Eukarya (like certain genetic sequences), they are still fundamentally different.
- **Statement 3**: "Archaea have some novel features that are absent in other prokaryotes and eukaryotes." This statement is true. Archaea possess unique features, such as specific types of ribosomal RNA and distinct membrane lipids.
- **Statement 4**: "Archaea completely differ from both prokaryotes and eukaryotes." This is misleading; while they are different, they still belong to the prokaryotic category.

4. **Conclusion**:
- The correct statement regarding Archaea is that they have some novel features that are absent in other prokaryotes and eukaryotes.

### Final Answer:
The true statement about Archaea is: **"Archaea have some novel features that are absent in other prokaryotes and eukaryotes."**