Question:

Which of the following statements is incorrect?

Viroid's lack a protein coat

Viruses are obligate parasites

Prions consist of abnormal folded proteins

Infective constituent in viruses is the protein coat

Solution:

Correct option is D. Infective constituent in viruses is the protein coat. Infective constituent of the virus is not the protein coat, but it is the nucleic acid, either DNA or RNA. So, the correct answer is 'Infective constituent in viruses is the protein coat'.