Archaea differ from bacteria in that they :
(a) can form methanogen
(b) have different rRNA sequences
(c) do not have peptidoglycan in their cell walls
(d) all of the above are correct

Options

A. can form methanogen
B. have different rRNA sequences
C. do not have peptidoglycan in their cell walls
D. all of the above are correct

Answer

To answer the question "Archaea differ from bacteria in that they:", we need to analyze each option provided:

1. **Option (a): Can form methanogen**
- Methanogens are a specific group of archaea that produce methane as a metabolic by-product. This characteristic is indeed true for archaea, as many of them are capable of producing methane.

2. **Option (b): Have different rRNA sequences**
- Archaea have distinct ribosomal RNA (rRNA) sequences compared to bacteria. This difference in rRNA sequences is one of the key factors that differentiate archaea from bacteria at a molecular level.

3. **Option (c): Do not have peptidoglycan in their cell walls**
- The cell walls of archaea are made of pseudomurein or pseudopeptidoglycans, unlike bacteria, which have peptidoglycan in their cell walls. This is another significant difference between the two groups.

4. **Option (d): All of the above are correct**
- Since all the previous statements (a, b, and c) are true, this option is also correct.

Based on the analysis of each option, the correct answer is:
**(d) all of the above are correct.**