Question

Which one of the following is an incorrect statement regarding Mycoplasma?
A. They lack a cell wall
B. They are the smallest living cells.
C. They cannot survive without oxygen.
D. They are pathogenic in plants and animals.

Answer 1

Hint: Mycoplasma is a genus of bacteria that lacks a cell wall around its cell membranes. Antibiotics that target cell wall synthesis are inherently resistant to them because of this trait (like the beta-lactam antibiotics). They can be parasitic or saprotrophic. Several species, notably M. pneumonia, which causes "walking" pneumonia and other respiratory illnesses, and M. genitalium, which is thought to be implicated in pelvic inflammatory diseases, are harmful in humans.

Complete answer:
Option A: They lack a cell wall: Mycoplasma does not have a cell wall. Several Mycoplasma species are common, and some of them can be intracellular infections that develop inside their hosts. This type of bacterial life is known as parasitic or saprophytic. Because the cells only survive in the regulated osmotic environment of other cells, cell walls are not required. So, this is a correct statement.
Option B: They are the smallest living cells: The tiniest living cells are members of Kingdom monera. Although Mycoplasma is the smallest living cell, it lacks a cell wall. These are unicellular creatures that can live in the absence of oxygen. So, this is a correct statement.
Option C: They cannot survive without oxygen: Mycoplasma spumans is a bacterium belonging to the Mycoplasma genus. The cell membrane of this genus of bacteria is not surrounded by a cell wall. Mycoplasma is the tiniest bacterial cell yet identified. They can survive without oxygen and have a diameter of around 0.1 m. So, this is an incorrect statement.
Option D: They are pathogenic in plants and animals: In animals and plants, almost all Mycoplasmas are pathogenic. Because of its capacity to adhere to cells, Mycoplasma may infect both animal and plant cells. They can survive despite the lack of a cell wall. This, however, is not the cause of its pathogenicity. So, this is a correct statement.

Thus, the answer is option C: They cannot survive without oxygen.

Note:
In the genus Mycoplasma, there are about 100 species. Mycoplasma belongs to the Mollicutes class of microbes, which are parasites or commensals of humans, animals, and plants. Mycoplasma is a genus of bacteria that lives in vertebrates and arthropods. In Mycoplasma and Phytoplasma, dietary nitrogen availability has been demonstrated to affect codon bias and genome evolution.