Which two features are typically present in bacterial cells but not in viruses?

• A. Capsid and envelope
• B. Cell wall and flagella
• C. Nucleoid and plasmids
• D. Ribosomes and DNA replication machinery

Answer: (D)

Think about what distinguishes a cellular organism from a virus. Bacteria are cells that carry out protein synthesis and replicate their own genome using their own molecular machinery. They have ribosomes to translate RNA into proteins and a set of enzymes that copy and maintain their DNA. Viruses, on the other hand, are not cells and cannot perform these core processes on their own; they depend on a host cell’s ribosomes and replication enzymes to produce viral proteins and duplicate their genome.

That’s why the two features that best fit being typical of bacterial cells but not of viruses are ribosomes and the DNA replication machinery. Ribosomes are the protein factories of the cell, and DNA replication machinery encompasses the enzymes needed to duplicate the genome. Viruses lack these components and must hijack a host’s systems to reproduce.

The other options describe structures or organizational features that aren’t universal or fundamental to bacterial cells in the same way. For instance, capsids and envelopes are viral coats, not bacterial traits; cell walls and flagella are common in many bacteria but not universal and not exclusive to bacterial cells; nucleoid and plasmids describe bacterial DNA organization, but some viruses don’t involve this kind of DNA organization at all.