Which of the following statements is incorrect?
- Infective constituent in viruses is the protein coat
- Prions consist of abnormally folded proteins
- Viroids lack a protein coat
- Viruses are obligate parasites
Answer
(1) Infective constituent in viruses is the protein coat
Solution
As per NCERT, a virus is a nucleoprotein; its genetic material (RNA or DNA) is infectious, while the protein coat (capsid) only protects the nucleic acid.
∴ Statement (1) is incorrect.
Prions are infectious agents made of abnormally folded proteins (2 correct); viroids are free RNA without a protein coat (3 correct); viruses multiply only inside living host cells, i.e., they are obligate parasites (4 correct).
Answer: (1)