Question 1

Which of the following best describes the main difference between (+) strand RNA viruses and (-) strand RNA viruses in terms of their replication strategy?

Accepted Answer

(+) strand RNA viruses can be directly translated by host ribosomes, while (-) strand RNA viruses require a transcriptase to synthesize a complementary (+) strand before translation.

Question 2

The high mutation rate in RNA viruses is primarily due to which of the following factors?

Accepted Answer

The viral replicase enzyme lacks proofreading activity.

Question 3

Which of the following statements about the life cycle of the poliovirus is correct?

Accepted Answer

The entire poliovirus (+) strand genome serves as mRNA and is translated into a single polyprotein, which is then cleaved by a viral protease.

Question 4

Which protein of SARS-CoV-2 is responsible for binding to the host cell receptor and facilitating viral entry?

Accepted Answer

Spike protein (S)

Question 5

What is the main reason why COVID-19 (SARS-CoV-2) spreads more rapidly than SARS-CoV-1?

Accepted Answer

COVID-19 binds to the ACE2 receptor with much higher affinity than SARS-CoV-1.

Question 6

Which of the following best explains the process of antigenic drift in influenza viruses?

Accepted Answer

Gradual accumulation of point mutations in the hemagglutinin and neuraminidase genes, leading to altered antigenic properties.

Question 7

Which enzyme is unique to retroviruses and is essential for their replication cycle?

Accepted Answer

Reverse transcriptase

Question 8

A patient is diagnosed with Hepatitis B. Which of the following statements about the Hepatitis B virus (HBV) life cycle is correct?

Accepted Answer

HBV synthesizes a DNA genome from an RNA intermediate using reverse transcriptase.

Question 9

Which of the following is a key difference between antigenic drift and antigenic shift in influenza viruses?

Accepted Answer

Antigenic drift results in minor changes, while antigenic shift can produce entirely new viral subtypes by reassortment of genome segments.

Question 10

Which of the following best describes the function of the large T-antigen in SV40 polyomavirus?

Accepted Answer

It inhibits the host tumor suppressor protein p53, potentially leading to cell transformation and cancer.

Question 11

Which of the following viruses is most commonly used as a vector for gene therapy due to its ability to deliver DNA into human cells?

Accepted Answer

Adenovirus

Question 12

Which of the following steps in the HIV life cycle is targeted by protease inhibitor drugs?

Accepted Answer

Cleavage of the viral polyprotein into mature functional proteins

Question 13

Which of the following statements about the structure of the Tobacco Mosaic Virus (TMV) is correct?

Accepted Answer

TMV has a helical capsid composed of capsomere proteins surrounding a single-stranded RNA genome.

Question 14

Which of the following best explains why the SARS-CoV-2 genome can encode many proteins even though it has only a few open reading frames (ORFs)?

Accepted Answer

The virus produces polyproteins that are cleaved by viral proteases into multiple mature proteins.

Question 15

Which of the following is a unique feature of the Mimivirus compared to most other viruses?

Accepted Answer

It has a very large genome with genes for some metabolic enzymes and aminoacyl-tRNA synthetases.

Question 16

Which of the following best describes the function of the neuraminidase protein in the influenza virus life cycle?

Accepted Answer

It helps release newly formed virions from the host cell by cleaving sialic acid residues.

Question 17

Which of the following viruses is associated with the development of cervical cancer due to its ability to integrate into the host genome?

Accepted Answer

Human Papillomavirus (HPV)

Question 18

Which of the following best describes the role of the replicase-transcriptase complex in coronaviruses?

Accepted Answer

It is responsible for both replicating the viral genome and transcribing subgenomic RNAs for protein synthesis.

Question 19

Which of the following is a correct sequence of events in the HIV replication cycle?

Accepted Answer

Fusion with host cell membrane → reverse transcription → integration into host genome → translation of viral proteins → assembly and release

Viruses of Plants and Animals: Structure, Genomics, and Life Cycles ch 11 part 2

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