Question

Which of the following statements is incorrect regarding various infectious agents?

• A. Prions consist of abnormally folded proteins.
• B. Viroids lack a protein coat.
• C. Viruses are obligate parasites.
• D. The infective constituent in viruses is the protein coat.

Answer 1

The correct option is D

The infective constituent in viruses is the protein coat.

The correct option is D.

Explanations of the correct option:

1. Infective constituents of viruses are their genetic materials, which can either be RNA or DNA and not the protein coat.
2. A virus is a biological entity that can only reproduce within a host.
3. Anatomically, viruses possess nucleic acids (DNA or RNA) which are encased within a protective protein coat.
4. These entities are able to infect all forms of life, ranging from bacteria to humans, and consequently, they bring about a multitude of diseases in their host.

Explanations of the incorrect options:

Option A:

1. The abnormally folded proteins in the prions, form aggregates and are known as amyloids.
2. These amyloids tend to get aggregated in the infected tissues and cause tissue damage and eventually cell death.

Option B:

1. Viroids are infectious, nonprotein‐coding, highly structured small circular low-molecular-weight ribonucleic acids (RNAs) able to replicate autonomously and induce diseases in higher plants.
2. Viroids are single-stranded covalently closed circular RNA molecules existing as highly base-paired rod-like structures.

Option C:

1. Viruses are small obligate intracellular parasites, which by definition contain either an RNA or DNA genome surrounded by a protective, virus-coded protein coat.
2. Viruses may be viewed as mobile genetic elements, most probably of cellular origin and characterized by a long co-evolution of virus and host.

Final answer: The infective constituent in viruses is the protein coat is the incorrect statement regarding infections agents.