Which of the following is NOT used as a criterion to classify viruses?

• A. Ability to perform photosynthesis
• B. Capsid symmetry
• C. Type of nucleic acid (DNA or RNA)
• D. Host range

Answer: (A)

Verified step by step guidance

1. Step 1: Understand that viruses are classified based on specific characteristics that reflect their structure, genetic material, and interaction with hosts.
2. Step 2: Review common criteria used for virus classification, such as capsid symmetry, which refers to the shape and arrangement of the protein coat surrounding the viral genome.
3. Step 3: Consider the type of nucleic acid present in the virus, which can be DNA or RNA, single-stranded or double-stranded, as this is a fundamental classification criterion.
4. Step 4: Recognize the host range, meaning the spectrum of organisms a virus can infect, which is also used to classify viruses because it reflects their biological specificity.
5. Step 5: Identify that the ability to perform photosynthesis is not a characteristic of viruses, as viruses do not carry out metabolic processes like photosynthesis; therefore, it is not used as a classification criterion.