4. Which of the following is considered acellular?Aspergillus fumigatusMycobacterium tuberculosisSulfolobus islandicusHepatitis B virus

Breakdown of the Problem

1. We need to identify which of the provided options is considered acellular.
2. The options given are various entities: a fungus, a bacterium, an archaea, and a virus.

Relevant Concepts

1. Acellular: An organism or entity that does not have a cellular structure. Viruses are typically classified as acellular because they do not have a cellular structure and cannot reproduce independently, as they require a host cell to replicate.
2. Fungi: Aspergillus fumigatus is a eukaryotic organism with a cellular structure.
3. Bacteria: Mycobacterium tuberculosis is a prokaryotic organism, which also has a cellular structure.
4. Archaea: Sulfolobus islandicus is another type of prokaryotic organism with cells as well.
5. Viruses: Hepatitis B virus has a simple structure and is classified as acellular.

Analysis and Detail

1. Aspergillus fumigatus: This is a type of fungus, thus it is cellular.
2. Mycobacterium tuberculosis: This bacterium has a cell wall and is considered cellular.
3. Sulfolobus islandicus: As an archaeon, it is also cellular.
4. Hepatitis B virus: This is a virus and does not have a cellular structure, making it acellular.

Verify and Summarize

Upon analyzing each option, it is clear that the only acellular entity in this list is the Hepatitis B virus, as the other three options are cellular organisms.

Final Answer

The acellular option is Hepatitis B virus.