Question

The organism which lacks a cell wall and can also live without oxygen are:
A. Thermoacidophiles
B. Methanogens
C. Archaebacteria
D. Mycoplasma

Answer 1

Hint: It is only the prokaryotic organisms that can survive without oxygen whereas all the eukaryotic organisms survive in the aerobic conditions.

Complete answer: The two conditions are given for an organism in the question-
1. Lacks a cell wall
2. Live without oxygen
We know that Mycoplasma is the smallest bacterium that can live without a cell wall and even in the absence of oxygen. It is an anaerobic bacterium. These organisms are also known as “Jokers of the plant kingdom.”
Thermoacidophiles and Methanogens belong to the archaebacteria. The archaebacteria are well known to survive in the extremely harsh environment and it is not possible to survive in the extremities without any cell wall otherwise the cell membrane will lose its fluid nature when exposed to the harsh environment.

Additional information: Mycoplasma can change its shape and size under the simulation of various environmental conditions. Since they are the parasite of plants so generally they are referred to as Jokers of the Plant Kingdom.
Alternatively, the first two options that are thermoacidophiles and methanogens belong to the category of the archaebacteria. Since these three options are interrelated and can not survive without a cell wall in the harsh environmental condition so we can say Mycoplasma is the correct option.

Note: Mycoplasmas are prokaryotes in the class Mollicutes and are the smallest free-living, self-replicating microorganisms.
All members of the class lack a protective cell wall; thus they are damaged simply when outside of the host and are very difficult to identify with most staining techniques.