A prokaryotic organism that causes TB, Plague and Cholera is :

Question

Accepted Answer

The correct option is (3):
The correct option is Bacteria. This is because bacteria are the only organisms listed that are classified as **prokaryotic**, meaning they are single-celled organisms that characteristically lack a membrane-bound nucleus and other complex organelles. Furthermore, the three major infectious diseases listed—Tuberculosis (caused by *Mycobacterium tuberculosis*), Plague (caused by *Yersinia pestis*), and Cholera (caused by *Vibrio cholerae*)—are all confirmed to be caused by specific species of bacteria. The pathogens responsible for these diseases are microscopic microbes characterized by their simple prokaryotic structure and ability to reproduce independently, fitting the definition of pathogenic bacteria perfectly. Therefore, Bacteria is the only choice that satisfies both the required microbiological classification (prokaryotic) and the specific disease etiology mentioned in the question.

The incorrect option is (1):
Protozoa are single-celled organisms, but they are classified as **eukaryotic** organisms, which means they possess a true nucleus and complex membrane-bound organelles, a distinct difference from prokaryotes. Their complex cellular structure fundamentally disqualifies them from the "prokaryotic" category requested in the question. While protozoa are significant human pathogens, they cause diseases such as malaria, amoebic dysentery, and giardiasis. They are not the causative agents for the three major diseases mentioned, which are strictly bacterial infections. Thus, Protozoa is incorrect based on both its cell structure and the specific diseases it causes.

The incorrect option is (2):
A Virus is the smallest of the pathogenic agents, but it is not classified as a prokaryotic organism because it is not a cell; it is an **obligate intracellular parasite**. A virus consists only of genetic material (DNA or RNA) enclosed in a protein coat, completely lacking the cellular machinery of both prokaryotes and eukaryotes. Viruses must enter and hijack a host cell to reproduce, distinguishing them from the independently living, replicating bacteria. Therefore, a virus is fundamentally neither a prokaryote nor the direct cause of the listed bacterial diseases.

The incorrect option is (4):
Fungi, much like Protozoa, are classified as **eukaryotic** organisms, possessing a true nucleus and other complex internal structures, making them fundamentally different from the prokaryotic bacteria. They can exist as single-celled yeasts or multicellular molds. Fungi are responsible for mycoses, or fungal infections, in humans, which include conditions such as ringworm, athlete's foot, and candidiasis. These infections are biologically and clinically separate from the bacterial diseases of TB, Plague, and Cholera. The significant difference in cellular structure and the diseases they cause makes Fungi an incorrect choice.