Answer:
Archaebacteria are obligate or facultative anaerobes, i.e., they flourish in the absence of oxygen and that is why only they can undergo methanogenesis.
The cell membranes of the Archaebacteria are composed of lipids.
The rigid cell wall provides shape and support to the Archaebacteria. It also protects the cell from bursting under hypotonic conditions.
The cell wall is composed of Pseudomurein, which prevents archaebacteria from the effects of Lysozyme. Lysozyme is an enzyme released by the immune system of the host, which dissolves the cell wall of pathogenic bacteria.
These do not possess membrane-bound organelles such as nuclei, endoplasmic reticulum, mitochondria, lysosomes or chloroplast. Its thick cytoplasm contains all the compounds required for nutrition and metabolism.
They can live in a variety of environments and are hence called extremophiles. They can survive in acidic and alkaline aquatic regions, and also in temperature above boiling point.
They can withstand a very high pressure of more than 200 atmospheres.
Archaebacteria are indifferent towards major antibiotics because they contain plasmids which have antibiotic resistance enzymes.
The mode of reproduction is asexual, known as binary fission.
They perform unique gene transcription.
The differences in their ribosomal RNA suggest that they diverged from both prokaryotes and eukaryotes.