Which of the following is a feature that may be found in viruses but never in bacteria?

• A. A protein capsid surrounding genetic material
• B. A cell wall composed of peptidoglycan
• C. Circular double-stranded DNA genome
• D. Ribosomes for protein synthesis

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the structural components of viruses and bacteria. Viruses are composed of genetic material (DNA or RNA) enclosed within a protein coat called a capsid, and sometimes an envelope. Bacteria are cellular organisms with complex structures including a cell wall, cytoplasm, and ribosomes.
2. Step 2: Analyze each option in the context of virus and bacterial features. For example, a cell wall composed of peptidoglycan is characteristic of bacteria but not viruses.
3. Step 3: Recognize that viruses do not have ribosomes for protein synthesis; they rely on host cells for this function, whereas bacteria have their own ribosomes.
4. Step 4: Note that circular double-stranded DNA genomes are common in bacteria, but viruses can have various types of genomes including RNA or linear DNA.
5. Step 5: Conclude that the presence of a protein capsid surrounding genetic material is unique to viruses and not found in bacteria, making it the distinguishing feature.