Question 40

Infection caused by a unicellular microorganism with a nucleus and cilia indicates a protozoan pathogen.

This type of infection is characteristic of protozoa, which are unicellular organisms that have a defined nucleus and may possess cilia for movement.

A) Viruses

Viruses are not unicellular organisms; they lack a cellular structure and cannot be classified as microorganisms with a nucleus. They are acellular and require a host cell to replicate, making them distinct from the described pathogen.

B) Helminths

Helminths are multicellular parasitic worms, not unicellular microorganisms. They do not possess cilia and are classified differently than protozoa, which are single-celled and can have cilia for locomotion.

C) Bacteria

Bacteria are unicellular organisms but do not possess a nucleus as they are prokaryotic. They lack the defined cellular structures that are characteristic of eukaryotic microorganisms like protozoa.

D) Protozoa

Protozoa are unicellular eukaryotic microorganisms that possess a nucleus and can have cilia for movement. This directly aligns with the characteristics described in the question, making this option the correct answer.

Conclusion

The correct identification of the pathogen as protozoa is based on its unicellular structure, presence of a nucleus, and potential for having cilia. Other options such as viruses, helminths, and bacteria do not meet these criteria, solidifying protozoa as the definitive answer in this context.