Quiz
Virology Midterm
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Questions in this quiz (44)
1A virion is a virus particle without the capsid.
- ATrue
- BFalse
2What are things that a virus cannot do on its own?
- ASynthesis of basic biological building blocks e.g. nucleotides, amino acids, carbohydrates, lipids etc.
- BGeneration of useable chemical energy (ATP)
- CProtein synthesis machinery
- DDoes not contain DNA
3What is it called when virus particles breakdown inside the cell and release genetic material?
- Auncoating
- Bdecoat
- Cencapsidate
4what is not one of the 4 major characteristics used for virus classification?
- AType of genome
- Bsymmetry of capsid
- Cpresence or absence of envelope
- Ddimensions
- Eenvelope proteins
5Genome data is used to understand evolutionary relationships and assign viruses to specific family.
- ATrue
- BFalse
6Which of the following statements correctly describes retrovirus replication?
- ARetroviruses have a DNA genome that is directly transcribed into mRNA by the host cell.
- BRetroviruses have an RNA genome that is converted to cDNA by an enzyme called reverse transcriptase.
- CRetroviruses replicate entirely in the cytoplasm using host RNA-dependent RNA polymerase.
7Why are red blood cells good for hemagglutination assay?
- Acarbohydrate-containing receptors on blood cells often bind with animal viruses
- Bblood cells have permeable membranes
- Cviruses are attracted to blood
8Some viruses use the host cell’s microtubule network to travel toward the nucleus. Which of the following correctly describes this process?
- AVirions attach to kinesin motors via the dynactin adapter complex to move toward the microtubule organizing center (MTOC).
- BVirions attach directly to microtubules and diffuse toward the microtubule organizing center (MTOC).
- CVirions bind to dynein motors via the dynactin adapter complex to move toward the microtubule organizing center (MTOC).
- DVirions bind to actin filaments and use dynein motors to move toward the nucleus.
9How do many DNA viruses deliver their genome into the host cell nucleus for replication?
- AThey use viral-encoded pumps to actively bore through the nuclear envelope.
- BThey exploit the host’s nuclear import pathway by interacting with importins that recognize nuclear localization signals (NLS), allowing transport through the nuclear pore complex (NPC).
- CThey dissolve the nuclear membrane during mitosis and enter passively.
- DThey fuse directly with the nuclear envelope using viral fusion proteins.
10Not all viruses that need to reach the nucleus enter through importins. What way do most retroviruses enter the nucleus out of all these plausible options?
- Acapsid injection at nuclear pore
- Bwhole small capsids enter through nuclear pores and disassemble in nucleus
- Center the nuclear capsid during mitosis
11Which statement best describes how a lysosomotropic agent disrupts viral entry?
- AIt binds directly to viral fusion proteins and prevents them from interacting with the endosomal membrane.
- BIt acts as a weak base that enters acidic organelles, becomes protonated, accumulates, and raises pH, preventing acid-dependent viral uncoating.
- CIt binds to monovalent cations and transports them across membranes to collapse proton gradients.
- DIt directly blocks the proton pump responsible for endosome acidification.
12A scientist adds monensin to a culture of cells infected with an acid-dependent virus. What is the primary mechanism by which monensin disrupts viral entry?
- AIt transports monovalent ions across endosomal membranes, disrupting ion gradients and preventing acidification.
- BIt accumulates in acidic compartments and directly absorbs protons.
- CIt blocks the vATPase proton pump to stop endosome acidification.
- DIt irreversibly denatures viral fusion proteins.
13Which of the following best explains how bafilomycin A1 prevents acidification of endosomes?
- AIt binds protons inside endosomes, directly raising the pH.
- BIt blocks the vacuolar ATPase (vATPase), preventing active transport of protons into the endosome.
- CIt creates pores in the endosomal membrane to allow H⁺ leakage.
- DIt exchanges sodium ions for protons, collapsing the pH gradient.
14Group 1: [blank_start]ssDNA genomes[blank_end] (small, without envelopes)
• Group 2: [blank_start]dsDNA genomes[blank_end] (widespread, can be very large)
• Group 3: [blank_start]+ strand RNA genomes[blank_end] (most common in plants, also found in vertebrates)
• Group 4: [blank_start]- strand RNA genomes[blank_end] (major infectious diseases in humans, helical nucleocapsids)
• Group 5: [blank_start]dsRNA genomes[blank_end] (mostly in fungi, segmented genomes)
• Group 6: [blank_start]Viruses that use reverse transcriptase[blank_end] (can be DNA or RNA)
• Group 7: [blank_start]Satellite viruses[blank_end], satellite nucleic acids, and viroids (very small genomes, highly
dependent on host cells and helper viruses for packaging or replication)- AssDNA genomes
- BdsDNA genomes
- C+ strand RNA genomes
- D- strand RNA genomes
- EdsRNA genomes
- FViruses that use reverse transcriptase
- GSatellite viruses
15Viruses that can encode proteins
directly are + strand RNA viruses- ATrue
- BFalse
16what kind of coronaviruses were the cause of the last 3 human outbreaks?
- AAlpha
- BBeta
- CDelta
- DGamma
17Corona virus is a negative sense double stranded RNA virus
- ATrue
- BFalse
18The genome of coronaviruses has a 5′ methylguanosine cap and a 3′ poly(A) tail. This structure is most similar to which of the following, and what is its primary advantage for the virus?
- AHost pre-mRNA; allows viral RNA to be spliced in the nucleus before translation.
- BMature eukaryotic mRNA; enables efficient translation by host ribosomes and protection from degradation.
- CProkaryotic mRNA; facilitates recognition by host ribosomes in the cytoplasm.
- DHost tRNA; ensures the viral genome is properly charged with amino acids.
19In coronaviruses, the first gene from the 5′ end of the genome is translated into a polyprotein. Which of the following best describes the function and processing of this polyprotein?
- AIt is a large precursor protein cleaved by host cell proteases into structural proteins for virion assembly.
- BIt is a large precursor protein cleaved by viral proteases into multiple non-structural proteins involved in genome replication and subgenomic mRNA synthesis.
- CIt is a long RNA molecule spliced into multiple transcripts encoding virion structural proteins.
- DIt is a host-derived protein complex recruited for viral genome packaging.
20Alphacoronaviruses, such as HCoV-229E, bind to which cellular receptor, and what is a key characteristic of this receptor family?
- AACE2; serine proteases that cleave peptide bonds using serine at the active site.
- BAminopeptidase-N; metalloproteinases that use metal ions in their catalytic mechanism.
- CDPP4; glycoproteins with high mannose content for viral attachment.
- DSialic acid; carbohydrate-binding lectins that recognize 9-carbon sugars.
21Which of the following correctly matches the receptor or co-factor with its role in SARS-CoV or SARS-CoV-2 entry?
- AACE2 – metalloproteinase that serves as the primary receptor for viral spike protein binding; L-SIGN – lectin that recognizes specific sugar motifs and acts as a co-receptor; TMPRSS2 – cellular serine protease that cleaves the spike protein at S2 to activate fusion.
- BACE2 – serine protease that cleaves the spike protein; L-SIGN – metalloproteinase receptor for spike protein; TMPRSS2 – carbohydrate-binding lectin co-receptor.
- CACE2 – metalloproteinase receptor for spike protein; L-SIGN – serine protease; TMPRSS2 – metalloproteinase involved in fusion.
- DACE2 – lectin receptor for spike protein; L-SIGN – carbohydrate-binding metalloproteinase; TMPRSS2 – carbohydrate-binding lectin.
22n coronaviruses, Gene 1 contains two partially overlapping reading frames, ORF1a and ORF1b. What is the main functional consequence of this overlap?
- AIt allows the same genomic region to be translated into two different polyproteins, depending on whether a ribosomal frameshift occurs during translation.
- BIt permits the virus to simultaneously translate structural and non-structural proteins from the same mRNA.
- CIt enables host ribosomes to initiate translation at multiple start codons along Gene 1 without frameshifting.
- DIt ensures that ORF1a is translated only after ORF1b has been fully processed by viral proteinases.
23Covid does not have proofreading capabilities during rna replication
- ATrue
- BFalse
24In coronaviruses, expression of only the M (membrane) and E (envelope) proteins in cells can result in the formation of virus-like particles (VLPs) in the ER–Golgi intermediate compartment (ERGIC). What does this observation most strongly indicate?
- AM and E are sufficient to drive envelope formation and budding, even without other viral proteins or genomic RNA.
- BE protein alone is responsible for packaging the full-length viral genome into virions.
- CM protein alone is responsible for glycosylating envelope proteins during transit through the Golgi.
- DN protein is required for membrane curvature and budding of all coronavirus particles.
25Picornaviruses are small (pico) RNA genome viruses with no lipid envelope
- ATrue
- BFalse
26Picornaviruses have a non-enveloped capsid made of 60 copies each of VP1, VP2, VP3, and VP4. Which of the following correctly describes the modifications found at the ends of the picornavirus genome?
- AThe 5′ end has a methylguanosine cap added by host capping enzymes, and the 3′ end has a poly(A) tail added by host poly(A) polymerase.
- BThe 5′ end is covalently bound to a viral VPg protein that acts in place of a 5′ cap, and the 3′ end contains a genome-encoded poly(A) tail rather than one added by poly(A) polymerase.
- CThe 5′ end has a viral VPg protein that functions as an RNA polymerase, and the 3′ end has no poly(A) sequence.
- DBoth the 5′ and 3′ ends are unmodified, relying on secondary RNA structure for stability.
27Picornaviruses lack a 5′ methylguanosine cap but can still efficiently translate their proteins in host cells. Which feature of their RNA enables this cap-independent translation?
- AA leader sequence rich in adenines that recruits host RNA polymerase II.
- BAn internal ribosome entry site (IRES) that allows ribosomes to bind and initiate translation without a 5′ cap.
- CA covalently attached VPg protein that directly acts as a ribosome-binding site.
- DRepeated transcription-regulating sequences (TRS) that attract ribosomes.
28All known internal ribosome entry site (IRES) elements share which structural and sequence feature that helps ensure accurate translation initiation?
- AA GC-rich stem-loop structure immediately downstream of the AUG start codon that stabilizes the ribosome after initiation.
- BA pyrimidine-rich tract located ~20–25 nucleotides upstream of the AUG start codon that helps position the ribosome correctly for translation initiation.
- CA purine-rich tract at the 5′ end of the genome that recruits cap-binding proteins for initiation.
- DA poly(A) tract upstream of the AUG that acts as a binding site for tRNA
Met
Met
.
29During picornavirus infection, host cap-dependent translation is shut down while viral protein synthesis continues. Which combination of events explains this switch?
- AeIF-4E is phosphorylated to increase cap recognition, and the viral IRES recruits the 60S subunit directly.
- BeIF-4G is cleaved by a viral protease, disrupting cap-dependent translation, while the viral IRES recruits the 40S ribosomal subunit with help from host proteins.
- CeIF-4G is cleaved by host proteases in response to infection, and VPg replaces the function of eIF-4E.
- DeIF-4E is degraded by the viral protease, and the IRES uses only viral proteins to assemble the ribosome.
30In picornavirus RNA replication, what is the role of uridylation of the VPg protein?
- AIt adds a methyl group to VPg so it can mimic a 5′ cap for translation initiation.
- BIt attaches uridine residues to VPg, allowing it to base-pair with the poly(A) tail and serve as a primer for negative-strand RNA synthesis.
- CIt adds adenine residues to VPg so it can bind the start codon in the positive-strand RNA.
- DIt replaces the need for RNA-dependent RNA polymerase in initiating replication.
31During picornavirus assembly, which of the following correctly describes the role of protomers?
- AA protomer is a structural subunit made of VP1, VP2, and VP3 that combines with VP0 to form the nucleocapsid.
- BA protomer is a complex of VP0, VP1, and VP3 that assembles with four others to form a pentamer, which is a building block of the capsid.
- CA protomer is the full capsid shell formed by the association of pentamers with viral RNA.
- DA protomer is the cleaved form of VP0 that results in VP2 and VP4 during virion maturation.
32Flaviviruses cause green screen and are triangular shaped
- ATrue
- BFalse
33The flavivirus virion contains an envelope and envelope proteins are arranged with icosahedral symmetry
- ATrue
- BFalse
34Flaviviruses have a poly-a tail
- ATrue
- BFalse
35Which pairing correctly matches the domains of the flavivirus E protein with their primary functions?
- ADomain I – receptor binding; Domain II – structural hinge; Domain III – fusion peptide exposure
- BDomain I – structural hinge; Domain II – contains the hydrophobic fusion peptide; Domain III – receptor binding via an immunoglobulin-like fold
- CDomain I – fusion peptide; Domain II – receptor binding; Domain III – structural hinge
- DDomain I – structural hinge; Domain II – receptor binding; Domain III – capsid assembly
36Which of the following best explains antibody-dependent enhancement (ADE) in dengue virus infection?
- ANeutralizing antibodies bind the virus and prevent it from attaching to its normal receptor, reducing infection severity.
- BNon-neutralizing or sub-neutralizing antibodies bind the virus, which is then taken up by cells expressing Fc receptors, leading to increased viral entry and more severe disease.
- CAntibodies activate complement, causing lysis of infected cells and enhanced viral replication.
- DAntibodies block viral entry through Fc receptor-mediated endocytosis, limiting tissue tropism.
37Which sequence best describes the intracellular life cycle of flavivirus from cell entry to genome replication?
- ABinding of E protein to receptor → direct fusion at plasma membrane → prM–E heterodimers protect E in cytoplasm → viral RNA translated into subgenomic mRNAs → genome replication occurs freely in cytosol without a – strand intermediate.
- BClathrin-mediated endocytosis → acidification of endosome triggers E dimer rearrangement to expose fusion peptide → fusion releases +ssRNA into cytoplasm → RNA translated as a single polyprotein in the ER → polyprotein cleaved by viral (NS2B/NS3A) and host proteases → prM–E heterodimers protect E until cleavage by furin → NS proteins form membrane-bound replicase complexes → – strand RNA made → used to produce excess + strands for translation, replication, and packaging.
- CClathrin-mediated endocytosis → genome directly replicated in endosome → prM–E heterodimers form after RNA synthesis → NS proteins translate before genome entry → fusion peptide exposed by cytoplasmic protease activity → genome packaged without a – strand intermediate.
- DDirect fusion with plasma membrane → prM cleaved immediately after entry → E proteins form homodimers before budding → RNA replicated using host DNA polymerase → packaging into ER vesicles.
38Humans and animals can get togaviruses and humans can pass it on
- ATrue
- BFalse
39Which of the following correctly describes Togavirus structure and entry?
- ANon-enveloped virus with a naked icosahedral capsid, enters via direct fusion at the plasma membrane.
- BEnveloped virus with icosahedral symmetry in both capsid and envelope glycoproteins; enters via clathrin-mediated endocytosis using E glycoprotein.
- CEnveloped virus with helical nucleocapsid; enters via pH-independent fusion in endosomes.
- DNaked virus with capsid proteins that form canyons for receptor binding.
40The Togavirus genome is:
- ASegmented –ssRNA with no cap or tail, translated into multiple monocistronic mRNAs.
- BLinear +ssRNA with 5′ methylated cap and 3′ poly(A) tail; non-structural proteins translated directly from genomic RNA, structural proteins from a subgenomic mRNA.
- CLinear +ssRNA with no 5′ cap or poly(A) tail; all proteins from a single polyprotein.
- DCircular dsRNA with inverted terminal repeats; non-structural proteins encoded on opposite strands.
41Which sequence correctly describes Togavirus replication and exit?
- AGenome uncoated → non-structural proteins translated → RNA replication → structural proteins translated → capsid assembles in cytoplasm → budding at plasma membrane.
- BGenome uncoated → capsid proteins translated first → non-structural proteins translated second → RNA replication → assembly in ER → exocytosis.
- CGenome uncoated → structural proteins translated from genomic RNA → non-structural proteins from subgenomic mRNA → assembly in nucleus → budding into ER.
- DGenome uncoated → RNA replication → structural and non-structural proteins co-translated from subgenomic mRNA → assembly at mitochondria → lysis.
42Which of the following correctly describes a key structural and genomic feature of viruses in the family Filoviridae?
- AIcosahedral, enveloped particles with a segmented +ssRNA genome ~8–10 kb in size.
- BFilamentous, enveloped particles with a helical nucleocapsid containing a non-segmented negative-sense ssRNA genome ~15–19 kb in size.
- CBullet-shaped, non-enveloped particles with a circular dsRNA genome ~15–19 kb in size.
- DSpherical, enveloped particles with a helical nucleocapsid containing segmented –ssRNA genome ~8–10 kb in size.
43Which of the following correctly describes a key genomic feature of Filoviridae and how it differs from many positive-sense RNA viruses?
- AFilovirus genomes have a non-segmented (–)ssRNA with seven genes in a conserved order, each transcribed into separate mRNAs (except GP, which is cleaved into GP1, GP2, or sGP), unlike many (+)ssRNA viruses that often translate their genome directly into a polyprotein.
- BFilovirus genomes have a segmented (–)ssRNA with seven genes, each transcribed into a polyprotein, unlike (+)ssRNA viruses that produce monocistronic transcripts.
- CFilovirus genomes have a non-segmented (+)ssRNA with seven genes, all translated from one mRNA, unlike (–)ssRNA viruses that must transcribe individual mRNAs first.
- DFilovirus genomes have a segmented (+)ssRNA with variable gene order, unlike (–)ssRNA viruses that have conserved order and separate transcripts.
44Why do Filoviridae (e.g., Ebola, Marburg) package their own RNA-dependent RNA polymerase (L) and its cofactor VP35 inside the virion, while many positive-sense RNA viruses do not?
- ABecause their (–)ssRNA genome can be directly translated by host ribosomes, so polymerase is needed only for replication.
- BBecause their (–)ssRNA genome cannot be directly translated and must first be transcribed into mRNA by a viral polymerase immediately upon entry.
- CBecause their (+)ssRNA genome is unstable without a packaged polymerase.
- DBecause host cells lack ribosomes that can recognize capped viral mRNAs.
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- Quiz on Virology Midterm, created by Dylan Colthirst on 25/06/2025.
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- Dylan Colthirst
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