Practice Questions

T4 bacteriophage possesses an icosahedral head, helical tail, and tail fibers, making it the classic example of a complex virus.

TMV infects tobacco and many related plants but cannot infect animal cells because of host specificity.

Naked viruses possess only a nucleic acid core surrounded by a protein capsid and are generally more resistant to environmental conditions.

Viral envelopes originate from host cell membranes and contain viral glycoproteins essential for attachment and entry.

Tobacco Mosaic Virus (TMV) is a classic example of a helical, positive-sense single-stranded RNA virus infecting plants.

Helical viruses have capsomeres arranged helically around the viral nucleic acid, producing a rod-like appearance.

Icosahedral viruses have a highly symmetrical capsid composed of 20 triangular faces, providing maximum stability.

Bacteriophages are viruses that specifically infect bacteria and play important roles in bacterial genetics and biotechnology.

Retroviruses, such as HIV, possess ssRNA and the enzyme reverse transcriptase, enabling synthesis of DNA from RNA.

Viruses contain either DNA or RNA as their genetic material, never both. This is the most fundamental basis of viral classification.