Bacteria as Prokaryotic Unicellular Organisms

Steps:

• Recall that bacteria belong to the domain Bacteria, characterized by prokaryotic cells lacking a nucleus.
• Eliminate options based on universal traits: all bacteria are single-celled, but not all share eukaryotic features or specific lifestyles.
• Verify against biology definitions: bacteria reproduce asexually and exist as prokaryotes without complex structures like hyphae.
• Confirm D matches the defining feature of being unicellular.

Why D is correct:

• By definition, bacteria are prokaryotic organisms that are always single-celled (unicellular), distinguishing them from multicellular eukaryotes.

Why the others are wrong:

• A: Not all bacteria are parasites; many are free-living, like those in soil or as decomposers.
• B: Bacteria lack a true nucleus; they are prokaryotes with DNA in a nucleoid region.
• C: Hyphae are fungal structures; bacteria do not form them.

Final answer: D