MCQs

Enveloped viruses commonly enter cells by membrane fusion or receptor-mediated endocytosis.

HIV infects human immune cells and therefore belongs to the animal viruses.

Complex viruses, such as bacteriophage T4, possess an icosahedral head, helical tail, and specialized attachment structures.

Hepatitis C virus belongs to the Flaviviridae family and contains a positive-sense ssRNA genome.

Retroviruses possess single-stranded RNA and use reverse transcriptase to synthesize DNA before replication. HIV is the best-known example.

Rabies virus travels through peripheral nerves to the central nervous system, causing fatal encephalitis if untreated.

Most plant viruses enter through wounds or are transmitted by insect vectors such as aphids because intact plant cell walls prevent direct entry.

The contractile tail sheath helps inject viral DNA through the bacterial cell wall into the host cytoplasm.

Lipid envelopes are easily disrupted by detergents, alcohol, and drying, resulting in loss of infectivity.

SARS-CoV-2 is an enveloped positive-sense single-stranded RNA virus belonging to the Coronaviridae family.

Zoonotic viruses naturally circulate among animals but can also infect humans. Rabies virus and some coronaviruses are examples.

Adenovirus lacks a lipid envelope and possesses an icosahedral protein capsid enclosing double-stranded DNA.

RNA polymerases lack efficient proofreading mechanisms, resulting in frequent mutations and rapid viral evolution.

Herpesviruses possess large linear double-stranded DNA genomes enclosed within an icosahedral capsid.

Negative-sense RNA cannot be translated directly. It must first be converted into positive-sense RNA by viral RNA-dependent RNA polymerase.

Human Papillomavirus infects epithelial tissues and is responsible for warts and cervical cancer.

Complex viruses, particularly bacteriophages, possess specialized structures like heads, tails, and tail fibers for host attachment.

TMV has a rod-shaped appearance due to its helical arrangement of capsid proteins around the RNA genome.

Coronaviruses possess one of the largest positive-sense single-stranded RNA genomes among viruses.