Question

Archaebacteria differ from eubacteria in

• A. cell membrane structure
• B. mode of nutrition
• C. cell shape
• D. mode of reproduction

Hint:

Key differences between Archaea and Bacteria:
- Cell membrane lipids (ether vs. ester linkages, branched vs. unbranched chains).
- Cell wall composition (peptidoglycan in most bacteria, pseudopeptidoglycan or other polymers in archaea).
- Ribosomal RNA sequences.
- Gene structure and replication mechanisms.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for a key distinguishing feature between Archaebacteria (Archaea) and Eubacteria (Bacteria).

Step 3: Detailed Explanation:
Archaea and Bacteria are two of the three domains of life (the third being Eukaryota). While both are prokaryotes, they differ significantly in several fundamental aspects, particularly at the molecular level.
* (a) Cell membrane structure: This is a major distinguishing feature.
* Eubacteria (Bacteria): Their cell membranes are composed of D-glycerol esters with unbranched fatty acid chains, and the linkages are ester bonds.
* Archaebacteria (Archaea): Their cell membranes are unique, composed of L-glycerol ethers with branched isoprene chains, and the linkages are ether bonds. This difference in lipid composition and bonding contributes to Archaea's ability to survive in extreme environments.
* (b) Mode of nutrition: Both Archaea and Bacteria exhibit diverse modes of nutrition (e.g., autotrophic - chemosynthesis/photosynthesis, heterotrophic). So, this is not a universal distinguishing feature.
* (c) Cell shape: Both Archaea and Bacteria come in various shapes (e.g., cocci, bacilli, spirilla). So, this is not a distinguishing feature.
* (d) Mode of reproduction: Both primarily reproduce asexually through binary fission. So, this is not a distinguishing feature.

Step 4: Final Answer:
Archaebacteria differ from eubacteria in cell membrane structure.