MDCAT-2026 Biology_11_Acellular_Life_MDCAT_ETEA_MCQs_2026 1 / 140 [ETEA-pattern | Hard | Comparison] Which statement correctly compares TMV and T4 phage? TMV is a helical plant virus, while T4 is a complex bacterial virus Both are spherical human viruses TMV contains a tail sheath T4 infects tobacco leaves TMV infects plants and has helical symmetry. T4 infects bacteria and has a head-tail structure. [ETEA-pattern | Hard] TMV infects plants and has helical symmetry. T4 infects bacteria and has a head-tail structure. [ETEA-pattern | Hard] 2 / 140 [ETEA-pattern | Hard | Comparison] Which statement correctly compares influenza and HIV? Both are enveloped RNA viruses, but HIV uses reverse transcription and influenza has a segmented genome Both are naked DNA viruses Both infect bacteria Both contain peptidoglycan Both have envelopes and RNA genomes. HIV is a retrovirus, whereas influenza carries segmented negative-sense RNA. [ETEA-pattern | Hard] Both have envelopes and RNA genomes. HIV is a retrovirus, whereas influenza carries segmented negative-sense RNA. [ETEA-pattern | Hard] 3 / 140 [ETEA-pattern | Hard | HIV lifecycle] A virion lacks reverse transcriptase but retains integrase and protease. Which earliest step fails? Conversion of RNA into viral DNA Insertion of DNA after it has formed Polyprotein cleavage Attachment through gp120 Without reverse transcriptase, the DNA intermediate cannot form. Integrase therefore lacks its substrate. [ETEA-pattern | Hard] Without reverse transcriptase, the DNA intermediate cannot form. Integrase therefore lacks its substrate. [ETEA-pattern | Hard] 4 / 140 [ETEA-pattern | Hard | HIV lifecycle] Which pair of viral enzymes acts in the correct chronological order after HIV entry? Reverse transcriptase, then integrase Protease, then lysozyme Integrase, then receptor binding Neuraminidase, then reverse transcriptase HIV first synthesizes DNA and then integrates it. Protease acts during maturation, while neuraminidase is an influenza enzyme. [ETEA-pattern | Hard] HIV first synthesizes DNA and then integrates it. Protease acts during maturation, while neuraminidase is an influenza enzyme. [ETEA-pattern | Hard] 5 / 140 [ETEA-pattern | Hard | HIV structure] A mutation in p17 would most directly disturb the: Matrix beneath the HIV envelope Reverse transcription active site Bacterial receptor TMV helical RNA p17 forms the HIV matrix. Reverse transcriptase is a separate viral enzyme. [ETEA-pattern | Hard] p17 forms the HIV matrix. Reverse transcriptase is a separate viral enzyme. [ETEA-pattern | Hard] 6 / 140 [ETEA-pattern | Hard | HIV structure] A mutation in p24 would most directly affect the: HIV capsid core Viral envelope lipid Host CD4 receptor Influenza neuraminidase p24 is the principal HIV capsid protein. Envelope lipid is host-derived and CD4 belongs to the host cell. [ETEA-pattern | Hard] p24 is the principal HIV capsid protein. Envelope lipid is host-derived and CD4 belongs to the host cell. [ETEA-pattern | Hard] 7 / 140 [ETEA-pattern | Hard | HIV structure] A mutation alters gp120. Which processes may be affected most directly? Receptor binding and antibody recognition Host ribosomal RNA synthesis Bacterial wall digestion Phage tail contraction gp120 mediates CD4 and co-receptor binding and is a major antibody target. The other processes belong to cells or bacteriophages. [ETEA-pattern | Hard] gp120 mediates CD4 and co-receptor binding and is a major antibody target. The other processes belong to cells or bacteriophages. [ETEA-pattern | Hard] 8 / 140 [ETEA-pattern | Hard | HIV pathogenesis] Why do antibodies alone fail to clear established HIV completely? Integrated provirus and rapidly evolving variants create persistent reservoirs and immune escape HIV contains no antigens Antibodies cannot bind proteins HIV exists only outside cells HIV integrates, persists in cells, and mutates extensively. It also has abundant protein antigens that antibodies can recognize. [ETEA-pattern | Hard] HIV integrates, persists in cells, and mutates extensively. It also has abundant protein antigens that antibodies can recognize. [ETEA-pattern | Hard] 9 / 140 [ETEA-pattern | Hard | HIV treatment] A patient's viral load remains high despite reported treatment. The next rational step is to assess: Adherence, drug interactions, and possible resistance Only eye colour Whether the virus has a cell wall TMV morphology Persistent viraemia requires clinical review of adherence, regimen, interactions, and resistance. Viral structure questions do not manage failure. [ETEA-pattern | Hard] Persistent viraemia requires clinical review of adherence, regimen, interactions, and resistance. Viral structure questions do not manage failure. [ETEA-pattern | Hard] 10 / 140 [ETEA-pattern | Hard | HIV treatment] A patient's viral load falls while CD4 count rises after ART. This pattern indicates: Virological suppression with immune recovery Immediate cure with loss of provirus Treatment failure Bacterial superinfection by definition Falling viral load and rising CD4 count are desired treatment responses. They do not prove eradication of HIV. [ETEA-pattern | Hard] Falling viral load and rising CD4 count are desired treatment responses. They do not prove eradication of HIV. [ETEA-pattern | Hard] 11 / 140 [ETEA-pattern | Hard | HIV treatment] Which factor most promotes emergence of drug-resistant HIV? Inconsistent medication adherence allowing replication under drug pressure Sustained complete suppression Correct condom use Routine confirmatory testing Intermittent drug exposure permits selection of resistant variants. Consistent adherence limits ongoing replication. [ETEA-pattern | Hard] Intermittent drug exposure permits selection of resistant variants. Consistent adherence limits ongoing replication. [ETEA-pattern | Hard] 12 / 140 [ETEA-pattern | Hard | HIV prevention] Which statement about HIV vaccination is correct for routine use in 2026? No licensed preventive HIV vaccine is available A universal vaccine is given at birth The polio vaccine prevents HIV ART is a vaccine No licensed preventive HIV vaccine is currently available. Prevention relies on testing, ART, PrEP, PEP, safer sex, and sterile equipment. [ETEA-pattern | Hard] No licensed preventive HIV vaccine is currently available. Prevention relies on testing, ART, PrEP, PEP, safer sex, and sterile equipment. [ETEA-pattern | Hard] 13 / 140 [ETEA-pattern | Hard | HIV treatment] Which statement about HIV cure is accurate in routine clinical practice? Current ART controls HIV but does not reliably eliminate latent infection A seven-day antibiotic course cures HIV Vaccination cures established infection Undetectable always means eradicated ART suppresses replication and protects health, yet latent provirus persists. Undetectable means controlled, not eliminated. [ETEA-pattern | Hard] ART suppresses replication and protects health, yet latent provirus persists. Undetectable means controlled, not eliminated. [ETEA-pattern | Hard] 14 / 140 [ETEA-pattern | Hard | HIV treatment] Which statement about ART timing is most accurate? ART should begin as soon as possible after confirmed diagnosis, with clinical evaluation ART should wait until AIDS develops ART is used only after antibiotics fail ART is stopped once viral load becomes undetectable Early ART reduces illness and transmission. Viral suppression requires continued treatment rather than stopping therapy. [ETEA-pattern | Hard] Early ART reduces illness and transmission. Viral suppression requires continued treatment rather than stopping therapy. [ETEA-pattern | Hard] 15 / 140 [ETEA-pattern | Hard | HIV treatment] A common modern initial ART strategy for many adults uses: An integrase inhibitor plus two nucleoside or nucleotide reverse-transcriptase inhibitors A penicillin plus an antifungal Only a protease inhibitor once No treatment until symptoms occur Many current regimens combine a second-generation integrase inhibitor with two NRTIs. Individual selection requires clinical assessment. [ETEA-pattern | Hard] Many current regimens combine a second-generation integrase inhibitor with two NRTIs. Individual selection requires clinical assessment. [ETEA-pattern | Hard] 16 / 140 [ETEA-pattern | Hard | HIV treatment] Why is ART normally prescribed as a combination? Multiple drugs suppress replication at different targets and reduce resistance One drug cannot enter blood Viruses require four antibiotics Combination therapy removes every provirus instantly Combination ART provides potent suppression and a higher barrier to resistance. It does not eradicate latent infection. [ETEA-pattern | Hard] Combination ART provides potent suppression and a higher barrier to resistance. It does not eradicate latent infection. [ETEA-pattern | Hard] 17 / 140 [ETEA-pattern | Hard | HIV prevention] Which intervention most reduces vertical HIV transmission? Effective maternal ART with appropriate obstetric and infant care Routine antibiotics only Avoiding all vaccines Delaying diagnosis until delivery Maternal viral suppression and linked perinatal care greatly reduce transmission during pregnancy, birth, and breastfeeding. [ETEA-pattern | Hard] Maternal viral suppression and linked perinatal care greatly reduce transmission during pregnancy, birth, and breastfeeding. [ETEA-pattern | Hard] 18 / 140 [ETEA-pattern | Hard | HIV prevention] After a significant recent exposure, the immediate prevention option is: Prompt clinical assessment for PEP Waiting for antibodies before seeking care Using PrEP after confirmed infection as sole treatment Taking antibacterial soap internally PEP is time-sensitive and should begin promptly after a qualifying exposure. Testing and follow-up accompany it. [ETEA-pattern | Hard] PEP is time-sensitive and should begin promptly after a qualifying exposure. Testing and follow-up accompany it. [ETEA-pattern | Hard] 19 / 140 [ETEA-pattern | Hard | HIV prevention] Which prevention combination is most comprehensive for an HIV-negative person at ongoing risk? Condoms, sterile injection equipment, regular testing, and PrEP when clinically appropriate Antibiotics and avoiding vaccination Only handwashing Chest radiography every month Combined biomedical and behavioral measures reduce risk. Antibiotics and routine radiography do not prevent HIV acquisition. [ETEA-pattern | Hard] Combined biomedical and behavioral measures reduce risk. Antibiotics and routine radiography do not prevent HIV acquisition. [ETEA-pattern | Hard] 20 / 140 [ETEA-pattern | Hard | HIV transmission] Which exposure is highest risk among the choices? Reuse of a contaminated hollow-bore needle Sitting beside a person with HIV Sharing a toilet Touching intact skin A contaminated needle can directly introduce infected blood. Casual environmental contact is not a transmission route. [ETEA-pattern | Hard] A contaminated needle can directly introduce infected blood. Casual environmental contact is not a transmission route. [ETEA-pattern | Hard] 21 / 140 [ETEA-pattern | Hard | HIV transmission] A mosquito bites a person with HIV and then another person. Why is this not a normal transmission route? HIV does not replicate in mosquitoes or get injected through their feeding mechanism Mosquitoes contain antibodies that cure HIV HIV is too large to enter blood Mosquitoes never contact human blood Mosquito biology does not support HIV replication or transfer in saliva. Their bites are not an epidemiological route. [ETEA-pattern | Hard] Mosquito biology does not support HIV replication or transfer in saliva. Their bites are not an epidemiological route. [ETEA-pattern | Hard] 22 / 140 [ETEA-pattern | Hard | HIV transmission] Which route does not transmit HIV in ordinary circumstances? Sharing food with a person who has HIV Sharing contaminated needles Exposure to infected blood Transmission during breastfeeding HIV is not spread by shared meals or casual contact. Blood exposure and vertical transmission are recognized routes. [ETEA-pattern | Hard] HIV is not spread by shared meals or casual contact. Blood exposure and vertical transmission are recognized routes. [ETEA-pattern | Hard] 23 / 140 [ETEA-pattern | Hard | HIV/AIDS] Which statement best distinguishes HIV infection from AIDS? HIV is the viral infection, while AIDS is its most advanced clinical stage AIDS is the virus and HIV is a symptom They are unrelated disorders AIDS always occurs immediately after transmission HIV names the causative virus and infection. AIDS describes advanced immune failure caused by HIV. [ETEA-pattern | Hard] HIV names the causative virus and infection. AIDS describes advanced immune failure caused by HIV. [ETEA-pattern | Hard] 24 / 140 [ETEA-pattern | Hard | HIV treatment] A person with HIV maintains an undetectable viral load on ART. Which statement is correct? They do not sexually transmit HIV while suppression is maintained They are cured and may stop ART They spread HIV by handshakes Their CD4 cells must be zero Sustained undetectable viral load prevents sexual transmission. ART remains necessary because latent infection persists. [ETEA-pattern | Hard] Sustained undetectable viral load prevents sexual transmission. ART remains necessary because latent infection persists. [ETEA-pattern | Hard] 25 / 140 [ETEA-pattern | Hard | HIV/AIDS] Which event defines progression toward AIDS most accurately? Advanced immune suppression with AIDS-defining illness or qualifying CD4 criteria Any single fever after exposure A positive screening test alone Presence of antibodies without immune damage AIDS is the advanced stage of HIV infection, not a synonym for every positive test or early symptom. [ETEA-pattern | Hard] AIDS is the advanced stage of HIV infection, not a synonym for every positive test or early symptom. [ETEA-pattern | Hard] 26 / 140 [ETEA-pattern | Hard | HIV complications] A person with untreated advanced HIV develops persistent cough and weight loss. A rational evaluation includes HIV labs plus: Investigation for opportunistic disease such as tuberculosis Only a skin allergy test No further assessment A bacterial phage culture Advanced HIV increases risk of TB and other opportunistic infections. Symptom-directed microbiology and chest imaging may be needed. [ETEA-pattern | Hard] Advanced HIV increases risk of TB and other opportunistic infections. Symptom-directed microbiology and chest imaging may be needed. [ETEA-pattern | Hard] 27 / 140 [ETEA-pattern | Hard | HIV diagnosis] Which imaging study routinely confirms HIV infection? No imaging study, diagnosis is laboratory based Chest X-ray Brain MRI Abdominal ultrasound HIV is diagnosed through laboratory tests. Imaging is ordered only to investigate complications such as pulmonary or neurological disease. [ETEA-pattern | Hard] HIV is diagnosed through laboratory tests. Imaging is ordered only to investigate complications such as pulmonary or neurological disease. [ETEA-pattern | Hard] 28 / 140 [ETEA-pattern | Hard | HIV diagnosis] Which measurement most directly estimates immune-system damage from HIV? CD4 T-cell count Viral capsid diameter Blood sodium only Platelet shape CD4 count reflects the degree of immune suppression. Viral load measures replication, not immune-cell reserve. [ETEA-pattern | Hard] CD4 count reflects the degree of immune suppression. Viral load measures replication, not immune-cell reserve. [ETEA-pattern | Hard] 29 / 140 [ETEA-pattern | Hard | HIV diagnosis] Which measurement is most useful for monitoring the amount of circulating HIV during treatment? Plasma viral load Chest circumference Blood group Serum calcium alone Viral-load testing measures HIV RNA and treatment response. CD4 count evaluates immune status rather than virus quantity. [ETEA-pattern | Hard] Viral-load testing measures HIV RNA and treatment response. CD4 count evaluates immune status rather than virus quantity. [ETEA-pattern | Hard] 30 / 140 [ETEA-pattern | Hard | HIV diagnosis] A reactive screening test should be interpreted as: Requiring confirmatory testing under the approved algorithm Proof that AIDS is already present Evidence that the person cannot transmit HIV A reason to delay care indefinitely A reactive screen is not the complete diagnosis by itself. Confirmatory testing separates true infection from false reactivity. [ETEA-pattern | Hard] A reactive screen is not the complete diagnosis by itself. Confirmatory testing separates true infection from false reactivity. [ETEA-pattern | Hard] 31 / 140 [ETEA-pattern | Hard | HIV diagnosis] Which test detects viral genetic material and can identify infection earliest among common test categories? Nucleic acid test Antibody-only test Chest radiograph Bacterial culture NAT detects HIV RNA and generally has the shortest window. It is used selectively because of cost and clinical context. [ETEA-pattern | Hard] NAT detects HIV RNA and generally has the shortest window. It is used selectively because of cost and clinical context. [ETEA-pattern | Hard] 32 / 140 [ETEA-pattern | Hard | HIV diagnosis] A person has no symptoms but reports a recent high-risk exposure. The best advice is to: Use appropriate HIV testing and repeat according to the test window if needed Wait for AIDS symptoms before testing Assume absence of infection Use a chest X-ray as the screening test HIV may be asymptomatic, and recent infection may fall within a window period. Testing and clinical guidance are required. [ETEA-pattern | Hard] HIV may be asymptomatic, and recent infection may fall within a window period. Testing and clinical guidance are required. [ETEA-pattern | Hard] 33 / 140 [ETEA-pattern | Hard | HIV diagnosis] A person has fever, rash, sore throat, and lymph-node enlargement two weeks after a high-risk exposure. The best conclusion is: Symptoms are compatible with acute HIV but laboratory testing is required AIDS is confirmed from symptoms alone HIV is impossible because symptoms appeared early Antibiotics confirm the diagnosis Acute HIV can resemble influenza, but symptoms are nonspecific. Diagnosis requires an approved testing algorithm. [ETEA-pattern | Hard] Acute HIV can resemble influenza, but symptoms are nonspecific. Diagnosis requires an approved testing algorithm. [ETEA-pattern | Hard] 34 / 140 [ETEA-pattern | Hard | HIV/AIDS] Why does progressive HIV infection impair both antibody and cell-mediated responses? CD4 helper cells coordinate activation of several immune-cell populations HIV removes all red blood cells HIV prevents every complement protein from forming HIV infects only platelets CD4 helper T cells coordinate B-cell, macrophage, and cytotoxic T-cell responses. Their loss disrupts multiple immune pathways. [ETEA-pattern | Hard] CD4 helper T cells coordinate B-cell, macrophage, and cytotoxic T-cell responses. Their loss disrupts multiple immune pathways. [ETEA-pattern | Hard] 35 / 140 [ETEA-pattern | Hard | HIV treatment] The long-lived latent reservoir that prevents ART from curing HIV mainly contains: Cells carrying integrated proviral DNA Free virions only in saliva Bacteria infected by HIV Red cells with viral ribosomes Integrated proviral DNA can persist in long-lived cells despite therapy. ART suppresses replication but does not remove every reservoir. [ETEA-pattern | Hard] Integrated proviral DNA can persist in long-lived cells despite therapy. ART suppresses replication but does not remove every reservoir. [ETEA-pattern | Hard] 36 / 140 [ETEA-pattern | Hard | HIV lifecycle] Which order correctly follows HIV replication after entry? Reverse transcription, integration, gene expression, assembly, budding, maturation Integration, attachment, reverse transcription, lysis Translation, entry, receptor binding, integration Budding, reverse transcription, uncoating, attachment HIV first makes DNA, integrates it, expresses viral products, assembles, buds, and matures. [ETEA-pattern | Hard] HIV first makes DNA, integrates it, expresses viral products, assembles, buds, and matures. [ETEA-pattern | Hard] 37 / 140 [ETEA-pattern | Hard | HIV treatment] A drug blocks HIV protease. Newly released particles are expected to be: Immature and poorly infectious Unable to bind CD4 because no RNA was made Converted into bacteriophages Free of envelopes Protease cleavage is required for structural maturation. Budding can occur, but particles remain immature and much less infectious. [ETEA-pattern | Hard] Protease cleavage is required for structural maturation. Budding can occur, but particles remain immature and much less infectious. [ETEA-pattern | Hard] 38 / 140 [ETEA-pattern | Hard | HIV treatment] A drug blocks integrase. HIV can still synthesize viral DNA, but cannot efficiently: Insert that DNA into the host chromosome Bind CD4 Fuse with the membrane Cleave mature proteins Integrase inhibition specifically blocks proviral integration. Entry and reverse transcription occur before this step. [ETEA-pattern | Hard] Integrase inhibition specifically blocks proviral integration. Entry and reverse transcription occur before this step. [ETEA-pattern | Hard] 39 / 140 [ETEA-pattern | Hard | HIV treatment] A drug blocks reverse transcriptase. Which viral product decreases first? DNA copied from HIV RNA Host-cell CD4 receptor Viral envelope lipids already present Bacterial peptidoglycan Reverse-transcriptase inhibition prevents formation of the viral DNA intermediate. It does not remove host CD4 or existing envelope lipid. [ETEA-pattern | Hard] Reverse-transcriptase inhibition prevents formation of the viral DNA intermediate. It does not remove host CD4 or existing envelope lipid. [ETEA-pattern | Hard] 40 / 140 [ETEA-pattern | Hard | HIV lifecycle] After gp120 binds CD4 and a co-receptor, gp41 chiefly promotes: Fusion of viral and cell membranes Reverse transcription Integration Polyprotein cleavage gp41 drives membrane fusion. Reverse transcriptase, integrase, and protease act at later stages. [ETEA-pattern | Hard] gp41 drives membrane fusion. Reverse transcriptase, integrase, and protease act at later stages. [ETEA-pattern | Hard] 41 / 140 [ETEA-pattern | Hard | HIV lifecycle] Which HIV component interacts first with the CD4 receptor? gp120 p24 p17 Integrase gp120 binds CD4 and a co-receptor. p24 and p17 are internal structural proteins, while integrase acts after entry. [ETEA-pattern | Hard] gp120 binds CD4 and a co-receptor. p24 and p17 are internal structural proteins, while integrase acts after entry. [ETEA-pattern | Hard] 42 / 140 [ETEA-pattern | Hard | HIV structure] A virus is described as enveloped, roughly spherical, and carrying two RNA copies plus reverse transcriptase. It is most likely: HIV TMV T4 phage Adenovirus This combination is characteristic of HIV. TMV is rod-shaped, T4 is complex, and adenovirus is a naked DNA virus. [ETEA-pattern | Hard] This combination is characteristic of HIV. TMV is rod-shaped, T4 is complex, and adenovirus is a naked DNA virus. [ETEA-pattern | Hard] 43 / 140 [ETEA-pattern | Hard | Host specificity] A plant virus cannot infect a bacterial culture mainly because: Its attachment and replication requirements do not match bacterial cells It lacks genetic material Bacteria contain no nucleic acids Plant viruses are larger than all bacteria Host specificity depends on compatible receptors and intracellular factors. The virus still possesses genetic material. [ETEA-pattern | Hard] Host specificity depends on compatible receptors and intracellular factors. The virus still possesses genetic material. [ETEA-pattern | Hard] 44 / 140 [ETEA-pattern | Hard | Applications] A cloning vector must enter a cell and carry foreign DNA. Which phage structure chiefly determines bacterial attachment? Tail fibres Viral RNA polymerase Lipid envelope Host ribosome Tail fibres recognize bacterial receptors, enabling DNA delivery. Phage vectors do not rely on a lipid envelope. [ETEA-pattern | Hard] Tail fibres recognize bacterial receptors, enabling DNA delivery. Phage vectors do not rely on a lipid envelope. [ETEA-pattern | Hard] 45 / 140 [ETEA-pattern | Hard | Phage cycles] Which difference most accurately separates a prophage from a provirus? Prophage refers specifically to phage DNA in bacteria, while provirus is used for integrated viral DNA in eukaryotic hosts Only proviruses contain DNA Only prophages replicate Proviruses are proteins The terms reflect host context. Both may represent integrated viral DNA and both can be copied with host chromosomes. [ETEA-pattern | Hard] The terms reflect host context. Both may represent integrated viral DNA and both can be copied with host chromosomes. [ETEA-pattern | Hard] 46 / 140 [ETEA-pattern | Hard | Phage cycles] A prophage is harmless to its host until stress activates viral replication. The transition is called: Induction Translation Conjugation Uncoating Induction ends lysogeny and initiates the lytic program. Conjugation is bacterial DNA transfer between cells. [ETEA-pattern | Hard] Induction ends lysogeny and initiates the lytic program. Conjugation is bacterial DNA transfer between cells. [ETEA-pattern | Hard] 47 / 140 [ETEA-pattern | Hard | Phage cycles] A bacterial culture survives while transmitting phage DNA to daughter cells. This observation indicates: Lysogeny Immediate lysis Animal-virus budding Prion replication Stable inheritance of phage DNA without host destruction is lysogeny. Lysis would rapidly destroy the culture. [ETEA-pattern | Hard] Stable inheritance of phage DNA without host destruction is lysogeny. Lysis would rapidly destroy the culture. [ETEA-pattern | Hard] 48 / 140 [ETEA-pattern | Hard | Bacteriophage] A mutation removes functional tail fibres from T4 phage. The earliest defect will involve: Receptor recognition Genome replication Late protein cleavage Host-cell lysis Tail fibres mediate initial bacterial recognition and attachment. Replication cannot begin without successful adsorption. [ETEA-pattern | Hard] Tail fibres mediate initial bacterial recognition and attachment. Replication cannot begin without successful adsorption. [ETEA-pattern | Hard] 49 / 140 [ETEA-pattern | Hard | Bacteriophage] A phage attaches normally but cannot contract its tail sheath. Which process is most directly blocked? Genome injection Capsid assembly Bacterial binary fission Prophage induction Tail contraction drives genome delivery in contractile phages. Attachment may occur, but penetration fails. [ETEA-pattern | Hard] Tail contraction drives genome delivery in contractile phages. Attachment may occur, but penetration fails. [ETEA-pattern | Hard] 50 / 140 [ETEA-pattern | Average | Replication] Compared with budding, lysis is more likely to: Release virions while immediately destroying the host cell Preserve the cell membrane completely Create a prophage Produce host antibodies Lysis ruptures the cell and releases particles. Budding may release virions without immediate cell destruction. [ETEA-pattern | Average] Lysis ruptures the cell and releases particles. Budding may release virions without immediate cell destruction. [ETEA-pattern | Average] 51 / 140 [ETEA-pattern | Average | Replication] Budding through a host membrane most directly allows a virus to acquire its: Ribosomes Envelope DNA polymerase in every case Peptidoglycan wall Enveloped viruses obtain a lipid membrane during budding. They do not acquire ribosomes or a bacterial wall. [ETEA-pattern | Average] Enveloped viruses obtain a lipid membrane during budding. They do not acquire ribosomes or a bacterial wall. [ETEA-pattern | Average] 52 / 140 [ETEA-pattern | Average | Replication] Uncoating refers to: Removal or disassembly of the capsid to expose the genome Assembly of capsomeres Integration of DNA into a chromosome Budding through the membrane Uncoating exposes the viral genome after entry. Assembly and budding occur later, while integration is limited to particular viruses. [ETEA-pattern | Average] Uncoating exposes the viral genome after entry. Assembly and budding occur later, while integration is limited to particular viruses. [ETEA-pattern | Average] 53 / 140 [ETEA-pattern | Average | Replication] Which sequence correctly orders the major steps of a typical animal-virus replication cycle? Attachment, entry, uncoating, biosynthesis, assembly, release Assembly, entry, attachment, release, uncoating Uncoating, attachment, lysis, entry, assembly Release, attachment, translation, entry, genome synthesis Attachment precedes entry and uncoating, followed by genome or protein synthesis, assembly, and release. [ETEA-pattern | Average] Attachment precedes entry and uncoating, followed by genome or protein synthesis, assembly, and release. [ETEA-pattern | Average] 54 / 140 [ETEA-pattern | Average | Host specificity] A mutation changes a viral attachment protein so it no longer binds its receptor. The immediate result is reduced: Entry into susceptible cells Genome replication after entry Host ATP production Capsid crystallization Receptor binding is required before entry. Later replication cannot occur if the virion cannot attach effectively. [ETEA-pattern | Average] Receptor binding is required before entry. Later replication cannot occur if the virion cannot attach effectively. [ETEA-pattern | Average] 55 / 140 [ETEA-pattern | Average | Host specificity] Two viruses carry similar genomes but use different attachment proteins. They may differ most directly in: Cells they can enter Presence of nucleic acid Need for host ribosomes Acellular organization Attachment proteins control receptor binding and therefore host range. Both viruses still require genomes and host translational machinery. [ETEA-pattern | Average] Attachment proteins control receptor binding and therefore host range. Both viruses still require genomes and host translational machinery. [ETEA-pattern | Average] 56 / 140 [ETEA-pattern | Average | Host specificity] A virus infects only cells displaying a particular receptor. This restriction primarily determines its: Host range and tissue tropism Genome size Ability to make ATP Capsomere number only Receptor compatibility governs which species and cell types can be infected. It does not provide independent metabolism. [ETEA-pattern | Average] Receptor compatibility governs which species and cell types can be infected. It does not provide independent metabolism. [ETEA-pattern | Average] 57 / 140 [ETEA-pattern | Average | Classification] Which virus is correctly classified as a naked RNA virus? Poliovirus HIV Influenza virus Herpesvirus Poliovirus is a non-enveloped positive-sense RNA virus. HIV and influenza are enveloped RNA viruses. [ETEA-pattern | Average] Poliovirus is a non-enveloped positive-sense RNA virus. HIV and influenza are enveloped RNA viruses. [ETEA-pattern | Average] 58 / 140 [ETEA-pattern | Average | Classification] Which virus is correctly classified as an enveloped DNA virus? Herpesvirus Poliovirus TMV T4 bacteriophage Herpesviruses are enveloped dsDNA viruses. Poliovirus is a naked RNA virus, TMV is a plant RNA virus, and T4 is non-enveloped. [ETEA-pattern | Average] Herpesviruses are enveloped dsDNA viruses. Poliovirus is a naked RNA virus, TMV is a plant RNA virus, and T4 is non-enveloped. [ETEA-pattern | Average] 59 / 140 [ETEA-pattern | Average | Classification] Which virus is a common example of a negative-sense, segmented RNA virus? Influenza virus Poliovirus Adenovirus Parvovirus Influenza possesses segmented negative-sense ssRNA. Poliovirus is positive-sense RNA, while adenovirus and parvovirus contain DNA. [ETEA-pattern | Average] Influenza possesses segmented negative-sense ssRNA. Poliovirus is positive-sense RNA, while adenovirus and parvovirus contain DNA. [ETEA-pattern | Average] 60 / 140 [ETEA-pattern | Average | Classification] Which virus is a common example of a positive-sense single-stranded RNA virus? Poliovirus Herpesvirus T4 bacteriophage Adenovirus Poliovirus has a positive-sense ssRNA genome. Herpesvirus, T4, and adenovirus are DNA viruses. [ETEA-pattern | Average] Poliovirus has a positive-sense ssRNA genome. Herpesvirus, T4, and adenovirus are DNA viruses. [ETEA-pattern | Average] 61 / 140 [ETEA-pattern | Average | Classification] Which example is correctly paired with its genome category? HIV, ssRNA-RT T4 phage, ssRNA TMV, dsDNA Influenza, circular dsDNA HIV is a single-stranded RNA retrovirus using reverse transcription. The other examples have mismatched genome types. [ETEA-pattern | Average] HIV is a single-stranded RNA retrovirus using reverse transcription. The other examples have mismatched genome types. [ETEA-pattern | Average] 62 / 140 [ETEA-pattern | Average | Classification] A genome described as dsDNA indicates: Two complementary DNA strands One RNA strand copied into DNA Two separate RNA segments A protein-only agent dsDNA means double-stranded DNA. It describes genome type, not segmentation or reverse transcription. [ETEA-pattern | Average] dsDNA means double-stranded DNA. It describes genome type, not segmentation or reverse transcription. [ETEA-pattern | Average] 63 / 140 [ETEA-pattern | Average | Classification] A naked virus differs from an enveloped virus by lacking a: Genome Capsid Lipid membrane outside the capsid Protein coat Naked viruses still contain genome and capsid but lack an outer lipid envelope. This distinction influences environmental stability and entry. [ETEA-pattern | Average] Naked viruses still contain genome and capsid but lack an outer lipid envelope. This distinction influences environmental stability and entry. [ETEA-pattern | Average] 64 / 140 [ETEA-pattern | Average | Classification] A virus with a head, contractile tail, base plate, and fibres is classified morphologically as: Helical only Complex Simple spherical Filamentous plant virus Head-tail phages have complex symmetry because they combine icosahedral and helical components with accessory structures. [ETEA-pattern | Average] Head-tail phages have complex symmetry because they combine icosahedral and helical components with accessory structures. [ETEA-pattern | Average] 65 / 140 [ETEA-pattern | Average | Classification] A virus with a helical capsid, RNA genome, and plant host is most consistent with: TMV T4 phage Adenovirus Herpesvirus TMV is a rod-shaped helical RNA plant virus. T4 is a complex bacteriophage and adenovirus is icosahedral. [ETEA-pattern | Average] TMV is a rod-shaped helical RNA plant virus. T4 is a complex bacteriophage and adenovirus is icosahedral. [ETEA-pattern | Average] 66 / 140 [ETEA-pattern | Average | Context] An infectious agent composed only of misfolded protein is a: Viroid Prion Virion Prophage Prions are infectious proteins lacking nucleic acid. Viroids contain RNA, while virions contain genome and capsid. [ETEA-pattern | Average] Prions are infectious proteins lacking nucleic acid. Viroids contain RNA, while virions contain genome and capsid. [ETEA-pattern | Average] 67 / 140 [ETEA-pattern | Average | Context] A newly discovered agent contains circular RNA but no capsid. It should be classified as a: Viroid Prion Bacteriophage Retrovirus Viroids are small infectious RNA molecules lacking a protein coat. Prions are infectious proteins without nucleic acid. [ETEA-pattern | Average] Viroids are small infectious RNA molecules lacking a protein coat. Prions are infectious proteins without nucleic acid. [ETEA-pattern | Average] 68 / 140 [ETEA-pattern | Average | Fundamentals] Which observation best supports the non-living character of a virus outside its host? Genome mutation Host specificity Metabolic inactivity and crystallization Antigenic variation Outside cells, virions are metabolically inert and may be crystallized. Mutation and antigenic variation require heritable genetic information. [ETEA-pattern | Average] Outside cells, virions are metabolically inert and may be crystallized. Mutation and antigenic variation require heritable genetic information. [ETEA-pattern | Average] 69 / 140 [ETEA-pattern | Average | Fundamentals] Which observation provides the strongest evidence for a living-like viral property? Virions can be crystallized Viruses evolve through mutation and selection Virions lack cytoplasm Viruses have no ribosomes Evolution through heritable variation is a living-like property. Crystallization and absence of cellular machinery reflect non-living characteristics. [ETEA-pattern | Average] Evolution through heritable variation is a living-like property. Crystallization and absence of cellular machinery reflect non-living characteristics. [ETEA-pattern | Average] 70 / 140 [ETEA-pattern | Average | Fundamentals] A particle has an RNA genome, a protein capsid, no ribosomes, and cannot reproduce in nutrient broth. It is best identified as a: Bacterium Virus Protozoan Fungal spore The combination of an acellular genome-capsid structure and host-dependent replication defines a virus. Bacteria contain ribosomes and can grow in suitable media. [ETEA-pattern | Average] The combination of an acellular genome-capsid structure and host-dependent replication defines a virus. Bacteria contain ribosomes and can grow in suitable media. [ETEA-pattern | Average] 71 / 140 [Attached-bank adaptation | Hard | HIV treatment] Which statement best explains why antibiotics do not cure HIV infection? HIV lacks bacterial structures and metabolic targets attacked by antibiotics HIV is too large for antibiotics HIV contains peptidoglycan that blocks drugs Antibiotics act only on human chromosomes Antibiotics target bacterial structures or pathways, while HIV is an acellular retrovirus. Antiretroviral drugs target viral replication instead. [Attached-bank adaptation | Hard] Antibiotics target bacterial structures or pathways, while HIV is an acellular retrovirus. Antiretroviral drugs target viral replication instead. [Attached-bank adaptation | Hard] 72 / 140 [Attached-bank adaptation | Hard | Replication] Which cell component is used directly for synthesis of viral proteins? Viral ribosomes Host-cell ribosomes Viral mitochondria Bacterial flagella Viruses lack ribosomes and translate their proteins on host ribosomes. Mitochondria and flagella are not virion components. [Attached-bank adaptation | Hard] Viruses lack ribosomes and translate their proteins on host ribosomes. Mitochondria and flagella are not virion components. [Attached-bank adaptation | Hard] 73 / 140 [Attached-bank adaptation | Hard | HIV prevention] Post-exposure prophylaxis, or PEP, is most effective when: Started promptly after a significant exposure under clinical guidance Delayed until AIDS appears Used as a vaccine years later Taken only after a negative chest X-ray PEP is an urgent short course begun as soon as possible after a qualifying exposure. It is not a vaccine or delayed treatment. [Attached-bank adaptation | Hard] PEP is an urgent short course begun as soon as possible after a qualifying exposure. It is not a vaccine or delayed treatment. [Attached-bank adaptation | Hard] 74 / 140 [Attached-bank adaptation | Hard | HIV prevention] Pre-exposure prophylaxis, or PrEP, is intended for: HIV-negative people at substantial risk before exposure Only people with untreated AIDS Bacterial pneumonia treatment Immediate viral diagnosis PrEP uses antiretroviral medication before potential exposure to reduce acquisition risk. It is not treatment for bacterial disease. [Attached-bank adaptation | Hard] PrEP uses antiretroviral medication before potential exposure to reduce acquisition risk. It is not treatment for bacterial disease. [Attached-bank adaptation | Hard] 75 / 140 [Attached-bank adaptation | Hard | HIV treatment] When ART maintains an undetectable viral load, sexual transmission of HIV is: Unchanged Effectively prevented, summarized as U equals U Guaranteed through saliva Converted into airborne spread Sustained viral suppression prevents sexual transmission, expressed as Undetectable equals Untransmittable. This does not mean HIV is cured. [Attached-bank adaptation | Hard] Sustained viral suppression prevents sexual transmission, expressed as Undetectable equals Untransmittable. This does not mean HIV is cured. [Attached-bank adaptation | Hard] 76 / 140 [Attached-bank adaptation | Hard | HIV prevention] A major reason HIV-vaccine development is difficult is the virus's: Complete absence of antigens Rapid genetic and antigenic variation Dependence on plant cells Inability to enter immune cells HIV evolves rapidly and displays extensive antigenic diversity. It certainly has antigens and specifically targets immune cells. [Attached-bank adaptation | Hard] HIV evolves rapidly and displays extensive antigenic diversity. It certainly has antigens and specifically targets immune cells. [Attached-bank adaptation | Hard] 77 / 140 [Attached-bank adaptation | Hard | HIV treatment] Current antiretroviral therapy generally: Eradicates every provirus Suppresses viral replication but does not cure HIV Works only for one week Increases viral load ART can reduce viral load to undetectable levels but does not remove all latent provirus. Lifelong adherence is usually required. [Attached-bank adaptation | Hard] ART can reduce viral load to undetectable levels but does not remove all latent provirus. Lifelong adherence is usually required. [Attached-bank adaptation | Hard] 78 / 140 [Attached-bank adaptation | Hard | HIV treatment] The standard treatment for HIV infection is: A single antibiotic course Combination antiretroviral therapy Surgical removal of lymph nodes No treatment until AIDS develops Combination ART suppresses viral replication and protects immune function. Treatment should begin promptly rather than waiting for AIDS. [Attached-bank adaptation | Hard] Combination ART suppresses viral replication and protects immune function. Treatment should begin promptly rather than waiting for AIDS. [Attached-bank adaptation | Hard] 79 / 140 [Attached-bank adaptation | Hard | HIV diagnosis] A negative HIV test immediately after a recent exposure may be unreliable because of the: Incubation of bacteria Diagnostic window period Permanent absence of antibodies Inability of HIV to enter blood Markers become detectable after different intervals, creating a window period. Repeat testing follows the test-specific schedule. [Attached-bank adaptation | Hard] Markers become detectable after different intervals, creating a window period. Repeat testing follows the test-specific schedule. [Attached-bank adaptation | Hard] 80 / 140 [Attached-bank adaptation | Hard | HIV diagnosis] The common laboratory screening approach for HIV includes detection of: HIV antigen and antibodies Only bacterial culture Blood glucose alone Chest radiography alone Laboratory antigen-antibody tests are widely used for screening. A reactive result requires testing according to a confirmatory algorithm. [Attached-bank adaptation | Hard] Laboratory antigen-antibody tests are widely used for screening. A reactive result requires testing according to a confirmatory algorithm. [Attached-bank adaptation | Hard] 81 / 140 [Attached-bank adaptation | Hard | HIV prevention] Screening donated blood chiefly prevents HIV transmission through: Respiratory droplets Transfusion of infected blood products Skin-to-skin contact Contaminated food Blood screening identifies infected donations before transfusion. HIV is not a foodborne or droplet-spread virus. [Attached-bank adaptation | Hard] Blood screening identifies infected donations before transfusion. HIV is not a foodborne or droplet-spread virus. [Attached-bank adaptation | Hard] 82 / 140 [Attached-bank adaptation | Hard | HIV prevention] Which measure most directly reduces sexual transmission of HIV? Correct condom use Antibiotics after every contact Avoiding vaccination Sharing razors Correct condom use reduces exposure to infectious fluids. Antibiotics do not prevent viral infection, and shared razors can create blood exposure. [Attached-bank adaptation | Hard] Correct condom use reduces exposure to infectious fluids. Antibiotics do not prevent viral infection, and shared razors can create blood exposure. [Attached-bank adaptation | Hard] 83 / 140 [Attached-bank adaptation | Hard | HIV transmission] Which statement about casual contact is correct? HIV spreads through handshakes HIV spreads by sharing food Ordinary hugging does not transmit HIV Mosquito bites are the main route HIV is not spread by ordinary day-to-day contact. Transmission requires exposure to particular infected body fluids. [Attached-bank adaptation | Hard] HIV is not spread by ordinary day-to-day contact. Transmission requires exposure to particular infected body fluids. [Attached-bank adaptation | Hard] 84 / 140 [Attached-bank adaptation | Hard | HIV transmission] Mother-to-child HIV transmission can occur during: Pregnancy, delivery, or breastfeeding Only after school age Casual hugging Sharing toys Vertical transmission may occur before birth, during delivery, or through breastfeeding. ART greatly reduces this risk. [Attached-bank adaptation | Hard] Vertical transmission may occur before birth, during delivery, or through breastfeeding. ART greatly reduces this risk. [Attached-bank adaptation | Hard] 85 / 140 [Attached-bank adaptation | Hard | HIV transmission] Which activity carries a clear HIV-transmission risk? Sharing contaminated injection equipment Sharing a classroom Using the same drinking glass Shaking hands Shared needles can transfer infected blood directly. Casual social contact does not transmit HIV. [Attached-bank adaptation | Hard] Shared needles can transfer infected blood directly. Casual social contact does not transmit HIV. [Attached-bank adaptation | Hard] 86 / 140 [Attached-bank adaptation | Hard | HIV transmission] Which body fluid is a recognized vehicle for HIV transmission? Sweat without blood Semen Tears Saliva during ordinary contact Semen can contain transmissible HIV. Ordinary contact with sweat, tears, or saliva does not transmit HIV. [Attached-bank adaptation | Hard] Semen can contain transmissible HIV. Ordinary contact with sweat, tears, or saliva does not transmit HIV. [Attached-bank adaptation | Hard] 87 / 140 [Attached-bank adaptation | Hard | HIV symptoms] A person with HIV may remain without obvious symptoms for years because: The virus has been eliminated Clinical latency can occur despite ongoing viral persistence HIV cannot replicate in humans All infected cells become resistant immediately HIV can persist and replicate at lower levels during clinical latency. Absence of symptoms does not mean elimination. [Attached-bank adaptation | Hard] HIV can persist and replicate at lower levels during clinical latency. Absence of symptoms does not mean elimination. [Attached-bank adaptation | Hard] 88 / 140 [Attached-bank adaptation | Hard | HIV symptoms] A possible early acute-HIV presentation is: Fever, rash, and swollen lymph nodes Immediate permanent paralysis Only severe jaundice Instant Kaposi sarcoma Acute HIV may cause a nonspecific influenza-like illness with fever, rash, sore throat, or lymphadenopathy. Many people have mild or no symptoms. [Attached-bank adaptation | Hard] Acute HIV may cause a nonspecific influenza-like illness with fever, rash, sore throat, or lymphadenopathy. Many people have mild or no symptoms. [Attached-bank adaptation | Hard] 89 / 140 [Attached-bank adaptation | Hard | HIV/AIDS] An opportunistic infection is one that: Occurs only in plants Takes advantage of weakened host defenses Always spreads through mosquitoes Cannot occur in healthy people under any condition Opportunistic pathogens cause serious disease when immunity is impaired. They are not defined by a single transmission route. [Attached-bank adaptation | Hard] Opportunistic pathogens cause serious disease when immunity is impaired. They are not defined by a single transmission route. [Attached-bank adaptation | Hard] 90 / 140 [Attached-bank adaptation | Hard | HIV/AIDS] The major biological consequence of progressive CD4-cell loss is: Excessive oxygen transport Increased susceptibility to opportunistic infections and cancers Faster blood clotting Permanent antibody overproduction CD4 loss weakens coordinated immunity, allowing opportunistic disease. Red-cell oxygen transport and clotting are unrelated. [Attached-bank adaptation | Hard] CD4 loss weakens coordinated immunity, allowing opportunistic disease. Red-cell oxygen transport and clotting are unrelated. [Attached-bank adaptation | Hard] 91 / 140 [Attached-bank adaptation | Hard | HIV/AIDS] The direct cause of AIDS is infection with: Influenza virus Human immunodeficiency virus T4 bacteriophage Tobacco mosaic virus HIV progressively damages immune function and can lead to AIDS. The other viruses do not cause this syndrome. [Attached-bank adaptation | Hard] HIV progressively damages immune function and can lead to AIDS. The other viruses do not cause this syndrome. [Attached-bank adaptation | Hard] 92 / 140 [Attached-bank adaptation | Hard | HIV/AIDS] AIDS stands for: Acute Infectious Deficiency State Acquired Immunodeficiency Syndrome Autoimmune Inflammatory Disease Syndrome Acquired Infection Detection System AIDS means Acquired Immunodeficiency Syndrome. It is the advanced stage of untreated or uncontrolled HIV infection. [Attached-bank adaptation | Hard] AIDS means Acquired Immunodeficiency Syndrome. It is the advanced stage of untreated or uncontrolled HIV infection. [Attached-bank adaptation | Hard] 93 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] HIV buds from the host cell as an immature particle and becomes infectious mainly after: Peptidoglycan synthesis Protease-mediated maturation Binary fission Capsid crystallization Protease processing reorganizes viral proteins into a mature infectious virion. Budding alone initially produces an immature particle. [Attached-bank adaptation | Hard] Protease processing reorganizes viral proteins into a mature infectious virion. Budding alone initially produces an immature particle. [Attached-bank adaptation | Hard] 94 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] Viral DNA integrated into a human chromosome during HIV infection is called a: Prophage Provirus Capsomere Plasmid Integrated retroviral DNA is a provirus. Prophage specifically refers to integrated phage DNA in bacteria. [Attached-bank adaptation | Hard] Integrated retroviral DNA is a provirus. Prophage specifically refers to integrated phage DNA in bacteria. [Attached-bank adaptation | Hard] 95 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] The first intracellular step after HIV fusion and uncoating is production of: Bacterial peptidoglycan DNA from viral RNA Antibodies from viral proteins ATP inside the virion Reverse transcription converts HIV RNA into DNA. Virions do not synthesize ATP or antibodies. [Attached-bank adaptation | Hard] Reverse transcription converts HIV RNA into DNA. Virions do not synthesize ATP or antibodies. [Attached-bank adaptation | Hard] 96 / 140 [Attached-bank adaptation | Hard | HIV/AIDS] The principal immune-cell target emphasized in HIV infection is the: Red blood cell CD4 helper T lymphocyte Platelet Neutrophil only HIV preferentially infects CD4-bearing cells, especially helper T lymphocytes. Red cells and platelets lack the required target system. [Attached-bank adaptation | Hard] HIV preferentially infects CD4-bearing cells, especially helper T lymphocytes. Red cells and platelets lack the required target system. [Attached-bank adaptation | Hard] 97 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] Which HIV enzyme cleaves viral polyproteins during maturation? Protease Reverse transcriptase Integrase RNA polymerase I HIV protease cuts precursor polyproteins into functional viral proteins. Reverse transcriptase and integrase act earlier. [Attached-bank adaptation | Hard] HIV protease cuts precursor polyproteins into functional viral proteins. Reverse transcriptase and integrase act earlier. [Attached-bank adaptation | Hard] 98 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] Which HIV enzyme inserts viral DNA into the host-cell chromosome? Protease Integrase Lysozyme Haemagglutinin Integrase catalyses insertion of viral DNA into host DNA. Protease acts later during virion maturation. [Attached-bank adaptation | Hard] Integrase catalyses insertion of viral DNA into host DNA. Protease acts later during virion maturation. [Attached-bank adaptation | Hard] 99 / 140 [Attached-bank adaptation | Hard | HIV lifecycle] Which HIV enzyme synthesizes DNA using viral RNA as template? Integrase Reverse transcriptase Protease Neuraminidase Reverse transcriptase makes viral DNA from RNA. Integrase inserts that DNA into host chromosomes. [Attached-bank adaptation | Hard] Reverse transcriptase makes viral DNA from RNA. Integrase inserts that DNA into host chromosomes. [Attached-bank adaptation | Hard] 100 / 140 [Attached-bank adaptation | Hard | HIV structure] The HIV genome contains: One copy of double-stranded DNA Two similar copies of single-stranded RNA Eight RNA segments A circular bacterial chromosome HIV virions package two copies of positive-sense single-stranded RNA. DNA appears later as a reverse-transcribed intermediate. [Attached-bank adaptation | Hard] HIV virions package two copies of positive-sense single-stranded RNA. DNA appears later as a reverse-transcribed intermediate. [Attached-bank adaptation | Hard] 101 / 140 [Attached-bank adaptation | Hard | HIV structure] The conical or bullet-like core of HIV is mainly built from: p17 p24 gp41 Haemagglutinin p24 forms the HIV capsid or core. p17 supports the matrix and gp41 participates in membrane fusion. [Attached-bank adaptation | Hard] p24 forms the HIV capsid or core. p17 supports the matrix and gp41 participates in membrane fusion. [Attached-bank adaptation | Hard] 102 / 140 [Attached-bank adaptation | Hard | HIV structure] The major matrix protein immediately beneath the HIV envelope is: p17 p24 gp120 CD4 p17 forms the HIV matrix layer. p24 is the capsid protein, while gp120 is a surface glycoprotein. [Attached-bank adaptation | Hard] p17 forms the HIV matrix layer. p24 is the capsid protein, while gp120 is a surface glycoprotein. [Attached-bank adaptation | Hard] 103 / 140 [Attached-bank adaptation | Hard | HIV structure] The outer spikes of HIV contain the glycoproteins: p17 and p24 gp120 and gp41 HA and NA CD4 and CCR5 HIV spikes contain gp120 and gp41. p17 is matrix protein, p24 forms the capsid, and CD4 is a host receptor. [Attached-bank adaptation | Hard] HIV spikes contain gp120 and gp41. p17 is matrix protein, p24 forms the capsid, and CD4 is a host receptor. [Attached-bank adaptation | Hard] 104 / 140 [Attached-bank adaptation | Hard | HIV structure] HIV is classified as a retrovirus because it: Contains ribosomes Uses reverse transcriptase to make DNA from RNA Has a bacterial cell wall Replicates by binary fission Retroviruses carry RNA and reverse transcriptase, producing a DNA intermediate. Ribosomes and binary fission are cellular features. [Attached-bank adaptation | Hard] Retroviruses carry RNA and reverse transcriptase, producing a DNA intermediate. Ribosomes and binary fission are cellular features. [Attached-bank adaptation | Hard] 105 / 140 [Attached-bank adaptation | Hard | Influenza] The influenza surface enzyme that helps newly formed virions separate from infected cells is: Haemagglutinin Neuraminidase Protease p10 DNA ligase Neuraminidase cleaves sialic-acid residues and assists viral release. Haemagglutinin primarily mediates attachment. [Attached-bank adaptation | Hard] Neuraminidase cleaves sialic-acid residues and assists viral release. Haemagglutinin primarily mediates attachment. [Attached-bank adaptation | Hard] 106 / 140 [Attached-bank adaptation | Hard | Influenza] The influenza surface protein that binds sialic-acid receptors during attachment is: Neuraminidase Haemagglutinin Reverse transcriptase Integrase Haemagglutinin mediates receptor binding and entry. Neuraminidase mainly assists release of progeny virions. [Attached-bank adaptation | Hard] Haemagglutinin mediates receptor binding and entry. Neuraminidase mainly assists release of progeny virions. [Attached-bank adaptation | Hard] 107 / 140 [Attached-bank adaptation | Hard | Structure] Influenza is placed among enveloped viruses because its nucleocapsid is surrounded by a: Cellulose wall Lipid-containing membrane Peptidoglycan layer Silica shell Influenza acquires a lipid envelope containing viral glycoproteins. Cellulose and peptidoglycan are cellular wall materials. [Attached-bank adaptation | Hard] Influenza acquires a lipid envelope containing viral glycoproteins. Cellulose and peptidoglycan are cellular wall materials. [Attached-bank adaptation | Hard] 108 / 140 [Attached-bank adaptation | Hard | Classification] The KPK text describes the influenza genome as being divided into: Two RNA segments Eight RNA segments Twenty DNA segments One circular RNA molecule Influenza A and B genomes contain eight RNA segments. A single circular genome is not characteristic of influenza. [Attached-bank adaptation | Hard] Influenza A and B genomes contain eight RNA segments. A single circular genome is not characteristic of influenza. [Attached-bank adaptation | Hard] 109 / 140 [Attached-bank adaptation | Hard | Classification] The genome of influenza A virus is: Double-stranded DNA Segmented single-stranded RNA Single circular DNA Double-stranded RNA with no envelope Influenza A has a segmented, negative-sense single-stranded RNA genome and an envelope. DNA options are incompatible with influenza biology. [Attached-bank adaptation | Hard] Influenza A has a segmented, negative-sense single-stranded RNA genome and an envelope. DNA options are incompatible with influenza biology. [Attached-bank adaptation | Hard] 110 / 140 [Attached-bank adaptation | Hard | Applications] Bacteriophages can serve as cloning vectors because they can: Translate human proteins without cells Carry inserted DNA into bacterial cells Synthesize ATP independently Convert proteins into DNA Phage genomes can carry recombinant DNA into bacteria. Host cells then copy the introduced sequence or express its product. [Attached-bank adaptation | Hard] Phage genomes can carry recombinant DNA into bacteria. Host cells then copy the introduced sequence or express its product. [Attached-bank adaptation | Hard] 111 / 140 [Attached-bank adaptation | Hard | Phage cycles] Induction of a lysogenic bacterium means that the prophage: Becomes a ribosome Leaves latency and enters the lytic pathway Changes into bacterial DNA permanently Is destroyed by binary fission Induction activates the prophage, leading toward viral replication and lysis. It does not convert the virus into a cellular organelle. [Attached-bank adaptation | Hard] Induction activates the prophage, leading toward viral replication and lysis. It does not convert the virus into a cellular organelle. [Attached-bank adaptation | Hard] 112 / 140 [Attached-bank adaptation | Hard | Phage cycles] During lysogeny, a prophage is usually copied when the bacterium: Translates antibodies Replicates its chromosome and divides Forms spores only Undergoes lysis immediately The prophage is replicated with host DNA and inherited by daughter cells. Immediate lysis would describe the lytic pathway. [Attached-bank adaptation | Hard] The prophage is replicated with host DNA and inherited by daughter cells. Immediate lysis would describe the lytic pathway. [Attached-bank adaptation | Hard] 113 / 140 [Attached-bank adaptation | Hard | Phage cycles] Integrated phage DNA within a bacterial chromosome is called a: Provirus Prophage Plasmid only Capsomere A prophage is phage DNA maintained in a lysogenic bacterium. Provirus is a broader term commonly used for integrated animal viral DNA. [Attached-bank adaptation | Hard] A prophage is phage DNA maintained in a lysogenic bacterium. Provirus is a broader term commonly used for integrated animal viral DNA. [Attached-bank adaptation | Hard] 114 / 140 [Attached-bank adaptation | Hard | Phage cycles] A phage capable of entering lysogeny is described as: Virulent only Temperate A prion A viroid Temperate phages can integrate or persist in a host before induction. Prions and viroids are distinct acellular agents. [Attached-bank adaptation | Hard] Temperate phages can integrate or persist in a host before induction. Prions and viroids are distinct acellular agents. [Attached-bank adaptation | Hard] 115 / 140 [Attached-bank adaptation | Hard | Phage cycles] A phage that characteristically follows the lytic cycle is called: Temperate Virulent Prophage Latent bacterium Virulent phages rapidly replicate and lyse the host. Temperate phages can establish lysogeny. [Attached-bank adaptation | Hard] Virulent phages rapidly replicate and lyse the host. Temperate phages can establish lysogeny. [Attached-bank adaptation | Hard] 116 / 140 [Attached-bank adaptation | Hard | Phage cycles] The event that releases newly assembled virions in a lytic phage infection is: Conjugation Lysis of the bacterium Binary fission of the phage Endocytosis Lysis ruptures the bacterial cell and releases progeny phages. Viruses do not reproduce by binary fission. [Attached-bank adaptation | Hard] Lysis ruptures the bacterial cell and releases progeny phages. Viruses do not reproduce by binary fission. [Attached-bank adaptation | Hard] 117 / 140 [Attached-bank adaptation | Hard | Phage cycles] After phage DNA redirects bacterial biosynthesis, the cell begins producing: Only bacterial DNA Viral nucleic acid and viral proteins Mitochondria Antibodies The host machinery synthesizes phage genomes and structural proteins. Antibodies are produced by vertebrate immune cells, not bacteria. [Attached-bank adaptation | Hard] The host machinery synthesizes phage genomes and structural proteins. Antibodies are produced by vertebrate immune cells, not bacteria. [Attached-bank adaptation | Hard] 118 / 140 [Attached-bank adaptation | Hard | Phage cycles] During T4-like phage penetration, which component usually enters the bacterium? The entire virion Only the viral nucleic acid Only the capsid The lipid envelope The phage genome enters through the tail, while most protein structures remain outside. Animal viruses often enter differently. [Attached-bank adaptation | Hard] The phage genome enters through the tail, while most protein structures remain outside. Animal viruses often enter differently. [Attached-bank adaptation | Hard] 119 / 140 [Attached-bank adaptation | Hard | Phage cycles] A phage-associated enzyme that locally opens the bacterial wall during penetration is: Lipase Lysozyme Reverse transcriptase Protease Lysozyme hydrolyses bacterial peptidoglycan and helps create an entry site. Reverse transcriptase is associated with retroviruses such as HIV. [Attached-bank adaptation | Hard] Lysozyme hydrolyses bacterial peptidoglycan and helps create an entry site. Reverse transcriptase is associated with retroviruses such as HIV. [Attached-bank adaptation | Hard] 120 / 140 [Attached-bank adaptation | Average | Phage cycles] The first event in the lytic cycle of a bacteriophage is: Host-cell lysis Attachment to a specific receptor Genome integration Virion assembly Attachment precedes penetration, biosynthesis, assembly, and lysis. Integration is characteristic of lysogeny rather than the initial lytic step. [Attached-bank adaptation | Average] Attachment precedes penetration, biosynthesis, assembly, and lysis. Integration is characteristic of lysogeny rather than the initial lytic step. [Attached-bank adaptation | Average] 121 / 140 [Attached-bank adaptation | Average | Fundamentals] Which structure is absent from every fully assembled virus particle? Genome Capsid protein Functional ribosomes Attachment protein Viruses lack ribosomes and must use host ribosomes. Genome and capsid are fundamental viral components, while attachment proteins are common. [Attached-bank adaptation | Average] Viruses lack ribosomes and must use host ribosomes. Genome and capsid are fundamental viral components, while attachment proteins are common. [Attached-bank adaptation | Average] 122 / 140 [Attached-bank adaptation | Average | Classification] An icosahedral capsid has: 12 faces 20 triangular faces 24 square faces 32 helical turns An icosahedron has 20 triangular faces. The other numbers do not define this common capsid symmetry. [Attached-bank adaptation | Average] An icosahedron has 20 triangular faces. The other numbers do not define this common capsid symmetry. [Attached-bank adaptation | Average] 123 / 140 [Attached-bank adaptation | Average | Bacteriophage] During phage infection, the hollow tail mainly serves as a: Site of translation Channel for nucleic-acid entry Lipid reservoir Protective envelope The tail forms a route through which phage nucleic acid enters the bacterium. The protein coat usually remains outside. [Attached-bank adaptation | Average] The tail forms a route through which phage nucleic acid enters the bacterium. The protein coat usually remains outside. [Attached-bank adaptation | Average] 124 / 140 [Attached-bank adaptation | Average | Bacteriophage] Tail fibres of a T4-like phage chiefly function in: Genome replication Recognition and attachment to the bacterium Protein synthesis ATP formation Tail fibres recognize bacterial surface receptors and anchor the phage. Replication and protein synthesis occur after entry using the host. [Attached-bank adaptation | Average] Tail fibres recognize bacterial surface receptors and anchor the phage. Replication and protein synthesis occur after entry using the host. [Attached-bank adaptation | Average] 125 / 140 [Attached-bank adaptation | Average | Bacteriophage] The head of a typical T4-like bacteriophage contains: Host ribosomes Viral nucleic acid Peptidoglycan Mitochondria The phage head or capsid encloses its genome. Ribosomes and mitochondria remain cellular structures, not virion components. [Attached-bank adaptation | Average] The phage head or capsid encloses its genome. Ribosomes and mitochondria remain cellular structures, not virion components. [Attached-bank adaptation | Average] 126 / 140 [Attached-bank adaptation | Average | Host specificity] The most direct function of viral attachment proteins is to: Produce ATP Bind specific receptors on susceptible host cells Translate viral mRNA Digest viral nucleic acid Attachment proteins recognize compatible host receptors and help determine host range. Viruses do not produce ATP or translate mRNA independently. [Attached-bank adaptation | Average] Attachment proteins recognize compatible host receptors and help determine host range. Viruses do not produce ATP or translate mRNA independently. [Attached-bank adaptation | Average] 127 / 140 [Attached-bank adaptation | Average | Structure] A viral envelope is primarily composed of: Peptidoglycan and cellulose Lipids with viral glycoproteins Chitin and protein DNA and histones Envelopes are lipid-rich membranes containing viral proteins or glycoprotein spikes. Peptidoglycan and chitin are cellular wall materials. [Attached-bank adaptation | Average] Envelopes are lipid-rich membranes containing viral proteins or glycoprotein spikes. Peptidoglycan and chitin are cellular wall materials. [Attached-bank adaptation | Average] 128 / 140 [Attached-bank adaptation | Average | Classification] Which classification pair is correctly matched? TMV, bacteriophage T4, plant virus HIV, animal virus Poliovirus, plant virus HIV infects human immune cells and is an animal virus. TMV infects plants, while T4 infects bacteria. [Attached-bank adaptation | Average] HIV infects human immune cells and is an animal virus. TMV infects plants, while T4 infects bacteria. [Attached-bank adaptation | Average] 129 / 140 [Attached-bank adaptation | Average | Classification] Poliovirus is best classified as a: Plant virus Bacteriophage Human animal virus Fungal virus Poliovirus infects humans and is therefore an animal virus by host classification. It does not infect plants or bacteria. [Attached-bank adaptation | Average] Poliovirus infects humans and is therefore an animal virus by host classification. It does not infect plants or bacteria. [Attached-bank adaptation | Average] 130 / 140 [Attached-bank adaptation | Average | Classification] A classic complex, tadpole-shaped virus is: TMV T4 bacteriophage Poliovirus Adenovirus T4 phage has an icosahedral head, tail, base plate, and fibres. TMV is helical and rod-shaped. [Attached-bank adaptation | Average] T4 phage has an icosahedral head, tail, base plate, and fibres. TMV is helical and rod-shaped. [Attached-bank adaptation | Average] 131 / 140 [Attached-bank adaptation | Average | Classification] A virus classified by host as a bacteriophage infects: Plants Fungi only Bacteria Protozoa only Bacteriophages are viruses of bacteria. Their name means bacteria-eaters, although they replicate rather than literally feed. [Attached-bank adaptation | Average] Bacteriophages are viruses of bacteria. Their name means bacteria-eaters, although they replicate rather than literally feed. [Attached-bank adaptation | Average] 132 / 140 [Attached-bank adaptation | Average | Classification] A rod-shaped plant virus used in classic virus studies is: HIV Tobacco mosaic virus T4 bacteriophage Poliovirus TMV has a rigid rod-like, helical nucleocapsid. T4 is complex and tadpole-shaped, while HIV is roughly spherical. [Attached-bank adaptation | Average] TMV has a rigid rod-like, helical nucleocapsid. T4 is complex and tadpole-shaped, while HIV is roughly spherical. [Attached-bank adaptation | Average] 133 / 140 [Attached-bank adaptation | Average | History] W. M. Stanley crystallized tobacco mosaic virus in: 1892 1917 1935 1953 Stanley crystallized TMV in 1935. The earlier dates relate to initial filtration studies or bacteriophage work. [Attached-bank adaptation | Average] Stanley crystallized TMV in 1935. The earlier dates relate to initial filtration studies or bacteriophage work. [Attached-bank adaptation | Average] 134 / 140 [Attached-bank adaptation | Average | History] The ability of tobacco mosaic virus to be crystallized mainly demonstrates its: Independent metabolism Non-cellular chemical organization outside cells Ability to divide by binary fission Presence of ribosomes Crystallization reflects the inert, non-cellular state of virions outside hosts. It does not show metabolism or cell division. [Attached-bank adaptation | Average] Crystallization reflects the inert, non-cellular state of virions outside hosts. It does not show metabolism or cell division. [Attached-bank adaptation | Average] 135 / 140 [Attached-bank adaptation | Average | Fundamentals] Viruses are called obligate intracellular parasites because they: Live only inside nuclei Replicate only through living host-cell machinery Always kill their hosts Contain only RNA Viral replication needs a living cell's enzymes, ribosomes, energy, and precursors. Many viruses replicate outside the nucleus or do not immediately kill hosts. [Attached-bank adaptation | Average] Viral replication needs a living cell's enzymes, ribosomes, energy, and precursors. Many viruses replicate outside the nucleus or do not immediately kill hosts. [Attached-bank adaptation | Average] 136 / 140 [Attached-bank adaptation | Average | Structure] The repeating protein subunits that build a capsid are called: Capsomeres Centromeres Chromomeres Peptidoglycans Capsomeres assemble into the capsid. Peptidoglycan belongs to bacterial cell walls and is absent from viral capsids. [Attached-bank adaptation | Average] Capsomeres assemble into the capsid. Peptidoglycan belongs to bacterial cell walls and is absent from viral capsids. [Attached-bank adaptation | Average] 137 / 140 [Attached-bank adaptation | Average | Structure] The protein coat directly surrounding a viral genome is the: Envelope Capsid Matrix Cell wall The capsid protects and packages the viral genome. An envelope is an optional outer lipid-containing layer derived largely from host membranes. [Attached-bank adaptation | Average] The capsid protects and packages the viral genome. An envelope is an optional outer lipid-containing layer derived largely from host membranes. [Attached-bank adaptation | Average] 138 / 140 [Attached-bank adaptation | Average | Fundamentals] The genome of a typical virus consists of: DNA and RNA together Either DNA or RNA Protein only DNA, RNA, and ribosomes A virus normally contains one type of nucleic acid as its genome. The strongest distractor wrongly combines DNA and RNA as genomic material. [Attached-bank adaptation | Average] A virus normally contains one type of nucleic acid as its genome. The strongest distractor wrongly combines DNA and RNA as genomic material. [Attached-bank adaptation | Average] 139 / 140 [Attached-bank adaptation | Average | Fundamentals] A complete extracellular infectious virus particle is called a: Capsomere Virion Prophage Nucleoid A virion is the complete infectious particle outside a host cell. A capsomere is only a protein subunit of the capsid. [Attached-bank adaptation | Average] A virion is the complete infectious particle outside a host cell. A capsomere is only a protein subunit of the capsid. [Attached-bank adaptation | Average] 140 items | 98 hard | 42 average | 70 attached-bank adaptations | 70 original ETEA-pattern | 70 attached-bank adaptations | 70 original ETEA-pattern 140 / 140 [Attached-bank adaptation | Average | Fundamentals] Which feature most clearly prevents a virus from being considered an independently living cell? It contains genetic material It can mutate It lacks autonomous metabolic and translational machinery It may possess a protein coat Viruses depend on host ribosomes and metabolism for reproduction. Genetic material and mutation are living-like properties, not evidence of cellular independence. [Attached-bank adaptation | Average] Viruses depend on host ribosomes and metabolism for reproduction. Genetic material and mutation are living-like properties, not evidence of cellular independence. [Attached-bank adaptation | Average] Your score isThe average score is 73% MDCAT-2025 Wrong shortcode initialized Wrong shortcode initialized
