Viruses:

• A. Contain both protein and nucleic acids.
• B. Infect only eukaryotic cells.
• C. Can grow in the absence of living cells.
• D. Are generally the same size as prokaryotes.
• E. Always kill the cells they infect.

Answer: (A)

Verified step by step guidance

1. Understand that viruses are composed of a protein coat called a capsid and nucleic acids, which can be either DNA or RNA. This is a fundamental characteristic of viruses.
2. Recognize that viruses can infect a wide range of hosts, including eukaryotic cells, prokaryotic cells (bacteria), and even archaea. They are not limited to infecting only eukaryotic cells.
3. Acknowledge that viruses cannot grow or replicate on their own in the absence of living cells. They require a host cell's machinery to reproduce, as they lack the necessary components for independent metabolism and replication.
4. Consider the size of viruses compared to prokaryotes. Viruses are generally much smaller than prokaryotic cells, often requiring electron microscopy to be visualized.
5. Understand that not all viruses kill the cells they infect. Some viruses can integrate into the host genome and remain dormant, while others may cause persistent infections without immediately killing the host cell.