Which of the following best describes the difference between a virus and a viroid?

• A. A virus can replicate independently in the environment, while a viroid requires a host cell for replication.
• B. A virus infects only plants, while a viroid infects only animals.
• C. A virus contains a protein coat and genetic material, while a viroid consists only of a short strand of circular RNA without a protein coat.
• D. A virus is composed solely of proteins, while a viroid is composed solely of DNA.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the basic definitions of viruses and viroids. A virus is a microscopic infectious agent that contains genetic material (DNA or RNA) enclosed within a protein coat called a capsid. Some viruses also have an outer lipid envelope.
2. Step 2: Recognize that viroids are much simpler infectious agents compared to viruses. Viroids consist solely of a short strand of circular RNA without any protein coat or capsid.
3. Step 3: Compare the structural components of viruses and viroids. Viruses have both genetic material and a protective protein coat, whereas viroids lack a protein coat and contain only RNA.
4. Step 4: Consider the host range and replication requirements. Both viruses and viroids require host cells to replicate; neither can replicate independently in the environment.
5. Step 5: Evaluate the given options based on these characteristics to identify the correct description of the difference between a virus and a viroid.