{ "chapter": "Acellular Life", "count": 100, "answerIndex": "zero-based", "notice": "Original practice items including related concept variants; not official examination questions.", "questions": [ { "id": "virus-envelope-entry", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "The host-derived envelope is removed from an otherwise intact influenza virion. Which function should decline most sharply?", "options": [ "Receptor-mediated entry", "Capsomere assembly", "Viral RNA synthesis", "Copying of host DNA" ], "answer": 0, "explanation": "Influenza envelope glycoproteins attach to host receptors and mediate membrane entry. Removing the envelope damages this earliest host-recognition step." }, { "id": "positive-rna", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Why can the genome of a positive-sense RNA virus begin directing protein synthesis soon after uncoating?", "options": [ "It contains host ribosomes", "It acts directly as mRNA", "It first becomes a prion", "It is always double-stranded" ], "answer": 1, "explanation": "Positive-sense RNA has the same readable orientation as mRNA, so host ribosomes can translate it directly." }, { "id": "negative-rna-polymerase", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "A negative-sense RNA virus enters a cell without a functional RNA-dependent RNA polymerase. What is the most immediate consequence?", "options": [ "Its capsid cannot attach", "Its DNA cannot integrate", "Its genome cannot produce readable mRNA", "Its envelope becomes bacterial" ], "answer": 2, "explanation": "Negative-sense RNA is complementary to mRNA. A viral polymerase must first make a positive-sense RNA that host ribosomes can read." }, { "id": "provirus", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which description identifies a provirus rather than a free virion?", "options": [ "Protein-only infectious agent", "Circular plant RNA without capsid", "Complete particle outside a host cell", "Viral DNA integrated into host DNA" ], "answer": 3, "explanation": "A provirus is a viral DNA stage integrated into the host genome. A virion is the complete extracellular infectious particle." }, { "id": "acellular-capsid-protection-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "A viral genome becomes enclosed by a complete capsid. Which outcome follows most directly?", "options": [ "The nucleic acid becomes better protected outside the host cell", "The virus fails to infect that cell efficiently", "It cannot independently synthesize proteins or reproduce", "The phage attaches to a susceptible bacterium" ], "answer": 0, "explanation": "The nucleic acid becomes better protected outside the host cell. Capsid proteins shield the genome from nucleases and environmental damage." }, { "id": "acellular-capsid-protection-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: the nucleic acid becomes better protected outside the host cell?", "options": [ "A virus lacks a surface protein able to bind a cell's receptor", "A viral genome becomes enclosed by a complete capsid", "A virion remains outside a living host cell", "A bacteriophage tail fibre recognizes a bacterial surface receptor" ], "answer": 1, "explanation": "The nucleic acid becomes better protected outside the host cell. Capsid proteins shield the genome from nucleases and environmental damage." }, { "id": "acellular-capsid-protection-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a viral genome becomes enclosed by a complete capsid, which explanation best links the change to its outcome?", "options": [ "Attachment requires molecular complementarity between viral ligands and host receptors", "Viruses lack ribosomes and the complete metabolic machinery required for replication", "Capsid proteins shield the genome from nucleases and environmental damage", "Specific binding anchors the particle before genome injection" ], "answer": 2, "explanation": "The nucleic acid becomes better protected outside the host cell. Capsid proteins shield the genome from nucleases and environmental damage." }, { "id": "acellular-host-specificity-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a virus lacks a surface protein able to bind a cell's receptor, which observation is most likely?", "options": [ "It cannot independently synthesize proteins or reproduce", "The bacterial cell ruptures and releases new phages", "The phage attaches to a susceptible bacterium", "The virus fails to infect that cell efficiently" ], "answer": 3, "explanation": "The virus fails to infect that cell efficiently. Attachment requires molecular complementarity between viral ligands and host receptors." }, { "id": "acellular-host-specificity-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "A learner records that the virus fails to infect that cell efficiently. Which preceding event best accounts for it?", "options": [ "A virus lacks a surface protein able to bind a cell's receptor", "A bacteriophage tail fibre recognizes a bacterial surface receptor", "A virion remains outside a living host cell", "A bacteriophage completes a lytic replication cycle" ], "answer": 0, "explanation": "The virus fails to infect that cell efficiently. Attachment requires molecular complementarity between viral ligands and host receptors." }, { "id": "acellular-host-specificity-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a virus lacks a surface protein able to bind a cell's receptor, which explanation best links the change to its outcome?", "options": [ "Viruses lack ribosomes and the complete metabolic machinery required for replication", "Attachment requires molecular complementarity between viral ligands and host receptors", "Viral components assemble before phage enzymes weaken the host wall and membrane", "Specific binding anchors the particle before genome injection" ], "answer": 1, "explanation": "The virus fails to infect that cell efficiently. Attachment requires molecular complementarity between viral ligands and host receptors." }, { "id": "acellular-host-specificity-integrated", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a virus lacks a surface protein able to bind a cell's receptor?", "options": [ "The phage attaches to a susceptible bacterium — Specific binding anchors the particle before genome injection", "It cannot independently synthesize proteins or reproduce — Viruses lack ribosomes and the complete metabolic machinery required for replication", "The virus fails to infect that cell efficiently — Attachment requires molecular complementarity between viral ligands and host receptors", "The bacterial cell ruptures and releases new phages — Viral components assemble before phage enzymes weaken the host wall and membrane" ], "answer": 2, "explanation": "The virus fails to infect that cell efficiently. Attachment requires molecular complementarity between viral ligands and host receptors." }, { "id": "acellular-obligate-parasite-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "A student models this change: A virion remains outside a living host cell. What should the model predict first?", "options": [ "The phage attaches to a susceptible bacterium", "The bacterial cell ruptures and releases new phages", "Virus-specific memory cells form without the full disease", "It cannot independently synthesize proteins or reproduce" ], "answer": 3, "explanation": "It cannot independently synthesize proteins or reproduce. Viruses lack ribosomes and the complete metabolic machinery required for replication." }, { "id": "acellular-obligate-parasite-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "What is the most likely cause when it cannot independently synthesize proteins or reproduce?", "options": [ "A virion remains outside a living host cell", "A bacteriophage completes a lytic replication cycle", "A safe viral antigen is introduced by vaccination", "A bacteriophage tail fibre recognizes a bacterial surface receptor" ], "answer": 0, "explanation": "It cannot independently synthesize proteins or reproduce. Viruses lack ribosomes and the complete metabolic machinery required for replication." }, { "id": "acellular-obligate-parasite-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a virion remains outside a living host cell, which explanation best links the change to its outcome?", "options": [ "Specific binding anchors the particle before genome injection", "Viruses lack ribosomes and the complete metabolic machinery required for replication", "Viral components assemble before phage enzymes weaken the host wall and membrane", "Adaptive lymphocytes undergo clonal selection after recognizing the antigen" ], "answer": 1, "explanation": "It cannot independently synthesize proteins or reproduce. Viruses lack ribosomes and the complete metabolic machinery required for replication." }, { "id": "acellular-obligate-parasite-integrated", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a virion remains outside a living host cell?", "options": [ "The phage attaches to a susceptible bacterium — Specific binding anchors the particle before genome injection", "The bacterial cell ruptures and releases new phages — Viral components assemble before phage enzymes weaken the host wall and membrane", "It cannot independently synthesize proteins or reproduce — Viruses lack ribosomes and the complete metabolic machinery required for replication", "Virus-specific memory cells form without the full disease — Adaptive lymphocytes undergo clonal selection after recognizing the antigen" ], "answer": 2, "explanation": "It cannot independently synthesize proteins or reproduce. Viruses lack ribosomes and the complete metabolic machinery required for replication." }, { "id": "acellular-bacteriophage-tail-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which immediate result is most consistent with this condition: A bacteriophage tail fibre recognizes a bacterial surface receptor?", "options": [ "The bacterial cell ruptures and releases new phages", "Virus-specific memory cells form without the full disease", "Its ability to enter host cells declines sharply", "The phage attaches to a susceptible bacterium" ], "answer": 3, "explanation": "The phage attaches to a susceptible bacterium. Specific binding anchors the particle before genome injection." }, { "id": "acellular-bacteriophage-tail-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which condition would most specifically produce this result: the phage attaches to a susceptible bacterium?", "options": [ "A bacteriophage tail fibre recognizes a bacterial surface receptor", "A bacteriophage completes a lytic replication cycle", "A safe viral antigen is introduced by vaccination", "A lipid-envelope virus is exposed to a detergent" ], "answer": 0, "explanation": "The phage attaches to a susceptible bacterium. Specific binding anchors the particle before genome injection." }, { "id": "acellular-bacteriophage-tail-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a bacteriophage tail fibre recognizes a bacterial surface receptor, which explanation best links the change to its outcome?", "options": [ "Viral components assemble before phage enzymes weaken the host wall and membrane", "Specific binding anchors the particle before genome injection", "Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "Detergent disrupts the membrane carrying the viral attachment and fusion proteins" ], "answer": 1, "explanation": "The phage attaches to a susceptible bacterium. Specific binding anchors the particle before genome injection." }, { "id": "acellular-bacteriophage-tail-integrated", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a bacteriophage tail fibre recognizes a bacterial surface receptor?", "options": [ "The bacterial cell ruptures and releases new phages — Viral components assemble before phage enzymes weaken the host wall and membrane", "Virus-specific memory cells form without the full disease — Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "The phage attaches to a susceptible bacterium — Specific binding anchors the particle before genome injection", "Its ability to enter host cells declines sharply — Detergent disrupts the membrane carrying the viral attachment and fusion proteins" ], "answer": 2, "explanation": "The phage attaches to a susceptible bacterium. Specific binding anchors the particle before genome injection." }, { "id": "acellular-lytic-release-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "A bacteriophage completes a lytic replication cycle. Which outcome follows most directly?", "options": [ "The prophage may leave the chromosome and enter the lytic cycle", "Virus-specific memory cells form without the full disease", "Its ability to enter host cells declines sharply", "The bacterial cell ruptures and releases new phages" ], "answer": 3, "explanation": "The bacterial cell ruptures and releases new phages. Viral components assemble before phage enzymes weaken the host wall and membrane." }, { "id": "acellular-lytic-release-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: the bacterial cell ruptures and releases new phages?", "options": [ "A bacteriophage completes a lytic replication cycle", "A safe viral antigen is introduced by vaccination", "A lipid-envelope virus is exposed to a detergent", "DNA damage activates an integrated bacteriophage genome" ], "answer": 0, "explanation": "The bacterial cell ruptures and releases new phages. Viral components assemble before phage enzymes weaken the host wall and membrane." }, { "id": "acellular-lytic-release-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a bacteriophage completes a lytic replication cycle, which explanation best links the change to its outcome?", "options": [ "Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "Viral components assemble before phage enzymes weaken the host wall and membrane", "Detergent disrupts the membrane carrying the viral attachment and fusion proteins", "Stress-induced regulatory changes switch viral genes from latency to active replication" ], "answer": 1, "explanation": "The bacterial cell ruptures and releases new phages. Viral components assemble before phage enzymes weaken the host wall and membrane." }, { "id": "acellular-lytic-release-integrated", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a bacteriophage completes a lytic replication cycle?", "options": [ "Virus-specific memory cells form without the full disease — Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "Its ability to enter host cells declines sharply — Detergent disrupts the membrane carrying the viral attachment and fusion proteins", "The bacterial cell ruptures and releases new phages — Viral components assemble before phage enzymes weaken the host wall and membrane", "The prophage may leave the chromosome and enter the lytic cycle — Stress-induced regulatory changes switch viral genes from latency to active replication" ], "answer": 2, "explanation": "The bacterial cell ruptures and releases new phages. Viral components assemble before phage enzymes weaken the host wall and membrane." }, { "id": "acellular-vaccine-antigen-outcome", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a safe viral antigen is introduced by vaccination, which observation is most likely?", "options": [ "Its ability to enter host cells declines sharply", "It cannot efficiently produce a DNA copy of its RNA genome", "The prophage may leave the chromosome and enter the lytic cycle", "Virus-specific memory cells form without the full disease" ], "answer": 3, "explanation": "Virus-specific memory cells form without the full disease. Adaptive lymphocytes undergo clonal selection after recognizing the antigen." }, { "id": "acellular-vaccine-antigen-cause", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "A learner records that virus-specific memory cells form without the full disease. Which preceding event best accounts for it?", "options": [ "A safe viral antigen is introduced by vaccination", "DNA damage activates an integrated bacteriophage genome", "A lipid-envelope virus is exposed to a detergent", "A retrovirus loses functional reverse transcriptase" ], "answer": 0, "explanation": "Virus-specific memory cells form without the full disease. Adaptive lymphocytes undergo clonal selection after recognizing the antigen." }, { "id": "acellular-vaccine-antigen-mechanism", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "After a safe viral antigen is introduced by vaccination, which explanation best links the change to its outcome?", "options": [ "Detergent disrupts the membrane carrying the viral attachment and fusion proteins", "Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "Stress-induced regulatory changes switch viral genes from latency to active replication" ], "answer": 1, "explanation": "Virus-specific memory cells form without the full disease. Adaptive lymphocytes undergo clonal selection after recognizing the antigen." }, { "id": "acellular-vaccine-antigen-integrated", "chapter": "Acellular Life", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a safe viral antigen is introduced by vaccination?", "options": [ "The prophage may leave the chromosome and enter the lytic cycle — Stress-induced regulatory changes switch viral genes from latency to active replication", "Its ability to enter host cells declines sharply — Detergent disrupts the membrane carrying the viral attachment and fusion proteins", "Virus-specific memory cells form without the full disease — Adaptive lymphocytes undergo clonal selection after recognizing the antigen", "It cannot efficiently produce a DNA copy of its RNA genome — Reverse transcriptase catalyses RNA-directed DNA synthesis before integration" ], "answer": 2, "explanation": "Virus-specific memory cells form without the full disease. Adaptive lymphocytes undergo clonal selection after recognizing the antigen." }, { "id": "acellular-envelope-detergent-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A student models this change: A lipid-envelope virus is exposed to a detergent. What should the model predict first?", "options": [ "The prophage may leave the chromosome and enter the lytic cycle", "It cannot efficiently produce a DNA copy of its RNA genome", "Both antibody and cytotoxic immune responses become poorly coordinated", "Its ability to enter host cells declines sharply" ], "answer": 3, "explanation": "Its ability to enter host cells declines sharply. Detergent disrupts the membrane carrying the viral attachment and fusion proteins." }, { "id": "acellular-envelope-detergent-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "What is the most likely cause when its ability to enter host cells declines sharply?", "options": [ "A lipid-envelope virus is exposed to a detergent", "A retrovirus loses functional reverse transcriptase", "HIV progressively destroys many CD4 helper T cells", "DNA damage activates an integrated bacteriophage genome" ], "answer": 0, "explanation": "Its ability to enter host cells declines sharply. Detergent disrupts the membrane carrying the viral attachment and fusion proteins." }, { "id": "acellular-envelope-detergent-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a lipid-envelope virus is exposed to a detergent, which explanation best links the change to its outcome?", "options": [ "Stress-induced regulatory changes switch viral genes from latency to active replication", "Detergent disrupts the membrane carrying the viral attachment and fusion proteins", "Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "Helper T-cell signals normally activate and sustain several adaptive immune pathways" ], "answer": 1, "explanation": "Its ability to enter host cells declines sharply. Detergent disrupts the membrane carrying the viral attachment and fusion proteins." }, { "id": "acellular-lysogenic-induction-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: DNA damage activates an integrated bacteriophage genome?", "options": [ "It cannot efficiently produce a DNA copy of its RNA genome", "Both antibody and cytotoxic immune responses become poorly coordinated", "The prophage may leave the chromosome and enter the lytic cycle", "Existing antibodies bind some new viral strains less effectively" ], "answer": 2, "explanation": "The prophage may leave the chromosome and enter the lytic cycle. Stress-induced regulatory changes switch viral genes from latency to active replication." }, { "id": "acellular-lysogenic-induction-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: the prophage may leave the chromosome and enter the lytic cycle?", "options": [ "Small mutations accumulate in viral surface-antigen genes", "A retrovirus loses functional reverse transcriptase", "HIV progressively destroys many CD4 helper T cells", "DNA damage activates an integrated bacteriophage genome" ], "answer": 3, "explanation": "The prophage may leave the chromosome and enter the lytic cycle. Stress-induced regulatory changes switch viral genes from latency to active replication." }, { "id": "acellular-lysogenic-induction-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After DNA damage activates an integrated bacteriophage genome, which explanation best links the change to its outcome?", "options": [ "Stress-induced regulatory changes switch viral genes from latency to active replication", "Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "Helper T-cell signals normally activate and sustain several adaptive immune pathways", "Altered epitopes reduce complementarity with antibodies generated against earlier strains" ], "answer": 0, "explanation": "The prophage may leave the chromosome and enter the lytic cycle. Stress-induced regulatory changes switch viral genes from latency to active replication." }, { "id": "acellular-lysogenic-induction-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: DNA damage activates an integrated bacteriophage genome?", "options": [ "It cannot efficiently produce a DNA copy of its RNA genome — Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "The prophage may leave the chromosome and enter the lytic cycle — Stress-induced regulatory changes switch viral genes from latency to active replication", "Both antibody and cytotoxic immune responses become poorly coordinated — Helper T-cell signals normally activate and sustain several adaptive immune pathways", "Existing antibodies bind some new viral strains less effectively — Altered epitopes reduce complementarity with antibodies generated against earlier strains" ], "answer": 1, "explanation": "The prophage may leave the chromosome and enter the lytic cycle. Stress-induced regulatory changes switch viral genes from latency to active replication." }, { "id": "acellular-reverse-transcription-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A retrovirus loses functional reverse transcriptase. Which outcome follows most directly?", "options": [ "Existing antibodies bind some new viral strains less effectively", "Both antibody and cytotoxic immune responses become poorly coordinated", "It cannot efficiently produce a DNA copy of its RNA genome", "A virus with a substantially new antigen combination can appear" ], "answer": 2, "explanation": "It cannot efficiently produce a DNA copy of its RNA genome. Reverse transcriptase catalyses RNA-directed DNA synthesis before integration." }, { "id": "acellular-reverse-transcription-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which change most directly explains this observation: it cannot efficiently produce a DNA copy of its RNA genome?", "options": [ "HIV progressively destroys many CD4 helper T cells", "Two influenza strains exchange genome segments in one host cell", "Small mutations accumulate in viral surface-antigen genes", "A retrovirus loses functional reverse transcriptase" ], "answer": 3, "explanation": "It cannot efficiently produce a DNA copy of its RNA genome. Reverse transcriptase catalyses RNA-directed DNA synthesis before integration." }, { "id": "acellular-reverse-transcription-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a retrovirus loses functional reverse transcriptase, which explanation best links the change to its outcome?", "options": [ "Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "Altered epitopes reduce complementarity with antibodies generated against earlier strains", "Helper T-cell signals normally activate and sustain several adaptive immune pathways", "Reassortment mixes segmented RNA genomes and may create novel surface proteins" ], "answer": 0, "explanation": "It cannot efficiently produce a DNA copy of its RNA genome. Reverse transcriptase catalyses RNA-directed DNA synthesis before integration." }, { "id": "acellular-reverse-transcription-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a retrovirus loses functional reverse transcriptase?", "options": [ "Both antibody and cytotoxic immune responses become poorly coordinated — Helper T-cell signals normally activate and sustain several adaptive immune pathways", "It cannot efficiently produce a DNA copy of its RNA genome — Reverse transcriptase catalyses RNA-directed DNA synthesis before integration", "A virus with a substantially new antigen combination can appear — Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Existing antibodies bind some new viral strains less effectively — Altered epitopes reduce complementarity with antibodies generated against earlier strains" ], "answer": 1, "explanation": "It cannot efficiently produce a DNA copy of its RNA genome. Reverse transcriptase catalyses RNA-directed DNA synthesis before integration." }, { "id": "acellular-hiv-cd4-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After HIV progressively destroys many CD4 helper T cells, which observation is most likely?", "options": [ "Existing antibodies bind some new viral strains less effectively", "A virus with a substantially new antigen combination can appear", "Both antibody and cytotoxic immune responses become poorly coordinated", "Clinical symptoms may disappear while the infection remains" ], "answer": 2, "explanation": "Both antibody and cytotoxic immune responses become poorly coordinated. Helper T-cell signals normally activate and sustain several adaptive immune pathways." }, { "id": "acellular-hiv-cd4-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A learner records that both antibody and cytotoxic immune responses become poorly coordinated. Which preceding event best accounts for it?", "options": [ "Small mutations accumulate in viral surface-antigen genes", "Two influenza strains exchange genome segments in one host cell", "A viral genome persists in host cells with limited gene expression", "HIV progressively destroys many CD4 helper T cells" ], "answer": 3, "explanation": "Both antibody and cytotoxic immune responses become poorly coordinated. Helper T-cell signals normally activate and sustain several adaptive immune pathways." }, { "id": "acellular-hiv-cd4-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After HIV progressively destroys many CD4 helper T cells, which explanation best links the change to its outcome?", "options": [ "Helper T-cell signals normally activate and sustain several adaptive immune pathways", "Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Latency minimizes particle production and immune detection until reactivation", "Altered epitopes reduce complementarity with antibodies generated against earlier strains" ], "answer": 0, "explanation": "Both antibody and cytotoxic immune responses become poorly coordinated. Helper T-cell signals normally activate and sustain several adaptive immune pathways." }, { "id": "acellular-hiv-cd4-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: HIV progressively destroys many CD4 helper T cells?", "options": [ "Existing antibodies bind some new viral strains less effectively — Altered epitopes reduce complementarity with antibodies generated against earlier strains", "Both antibody and cytotoxic immune responses become poorly coordinated — Helper T-cell signals normally activate and sustain several adaptive immune pathways", "A virus with a substantially new antigen combination can appear — Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Clinical symptoms may disappear while the infection remains — Latency minimizes particle production and immune detection until reactivation" ], "answer": 1, "explanation": "Both antibody and cytotoxic immune responses become poorly coordinated. Helper T-cell signals normally activate and sustain several adaptive immune pathways." }, { "id": "acellular-antigenic-drift-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A student models this change: Small mutations accumulate in viral surface-antigen genes. What should the model predict first?", "options": [ "A virus with a substantially new antigen combination can appear", "Clinical symptoms may disappear while the infection remains", "Existing antibodies bind some new viral strains less effectively", "Nearby cells become more resistant to viral replication" ], "answer": 2, "explanation": "Existing antibodies bind some new viral strains less effectively. Altered epitopes reduce complementarity with antibodies generated against earlier strains." }, { "id": "acellular-antigenic-drift-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "What is the most likely cause when existing antibodies bind some new viral strains less effectively?", "options": [ "Two influenza strains exchange genome segments in one host cell", "A viral genome persists in host cells with limited gene expression", "A virus-infected cell releases type I interferons", "Small mutations accumulate in viral surface-antigen genes" ], "answer": 3, "explanation": "Existing antibodies bind some new viral strains less effectively. Altered epitopes reduce complementarity with antibodies generated against earlier strains." }, { "id": "acellular-antigenic-drift-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After small mutations accumulate in viral surface-antigen genes, which explanation best links the change to its outcome?", "options": [ "Altered epitopes reduce complementarity with antibodies generated against earlier strains", "Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Latency minimizes particle production and immune detection until reactivation", "Interferon signalling induces antiviral proteins that inhibit genome copying and translation" ], "answer": 0, "explanation": "Existing antibodies bind some new viral strains less effectively. Altered epitopes reduce complementarity with antibodies generated against earlier strains." }, { "id": "acellular-antigenic-drift-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: small mutations accumulate in viral surface-antigen genes?", "options": [ "A virus with a substantially new antigen combination can appear — Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Existing antibodies bind some new viral strains less effectively — Altered epitopes reduce complementarity with antibodies generated against earlier strains", "Clinical symptoms may disappear while the infection remains — Latency minimizes particle production and immune detection until reactivation", "Nearby cells become more resistant to viral replication — Interferon signalling induces antiviral proteins that inhibit genome copying and translation" ], "answer": 1, "explanation": "Existing antibodies bind some new viral strains less effectively. Altered epitopes reduce complementarity with antibodies generated against earlier strains." }, { "id": "acellular-antigenic-shift-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Two influenza strains exchange genome segments in one host cell?", "options": [ "Clinical symptoms may disappear while the infection remains", "Nearby cells become more resistant to viral replication", "A virus with a substantially new antigen combination can appear", "Attachment and entry into host cells are reduced" ], "answer": 2, "explanation": "A virus with a substantially new antigen combination can appear. Reassortment mixes segmented RNA genomes and may create novel surface proteins." }, { "id": "acellular-antigenic-shift-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: a virus with a substantially new antigen combination can appear?", "options": [ "Antibodies cover a virus's receptor-binding proteins", "A viral genome persists in host cells with limited gene expression", "A virus-infected cell releases type I interferons", "Two influenza strains exchange genome segments in one host cell" ], "answer": 3, "explanation": "A virus with a substantially new antigen combination can appear. Reassortment mixes segmented RNA genomes and may create novel surface proteins." }, { "id": "acellular-antigenic-shift-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After two influenza strains exchange genome segments in one host cell, which explanation best links the change to its outcome?", "options": [ "Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Latency minimizes particle production and immune detection until reactivation", "Interferon signalling induces antiviral proteins that inhibit genome copying and translation", "Neutralization blocks the viral structures needed to recognize cellular receptors" ], "answer": 0, "explanation": "A virus with a substantially new antigen combination can appear. Reassortment mixes segmented RNA genomes and may create novel surface proteins." }, { "id": "acellular-antigenic-shift-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: two influenza strains exchange genome segments in one host cell?", "options": [ "Clinical symptoms may disappear while the infection remains — Latency minimizes particle production and immune detection until reactivation", "A virus with a substantially new antigen combination can appear — Reassortment mixes segmented RNA genomes and may create novel surface proteins", "Nearby cells become more resistant to viral replication — Interferon signalling induces antiviral proteins that inhibit genome copying and translation", "Attachment and entry into host cells are reduced — Neutralization blocks the viral structures needed to recognize cellular receptors" ], "answer": 1, "explanation": "A virus with a substantially new antigen combination can appear. Reassortment mixes segmented RNA genomes and may create novel surface proteins." }, { "id": "acellular-latent-virus-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A viral genome persists in host cells with limited gene expression. Which outcome follows most directly?", "options": [ "Attachment and entry into host cells are reduced", "Nearby cells become more resistant to viral replication", "Clinical symptoms may disappear while the infection remains", "More proteins adopt the abnormal aggregation-prone shape" ], "answer": 2, "explanation": "Clinical symptoms may disappear while the infection remains. Latency minimizes particle production and immune detection until reactivation." }, { "id": "acellular-latent-virus-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which change most directly explains this observation: clinical symptoms may disappear while the infection remains?", "options": [ "A virus-infected cell releases type I interferons", "A misfolded prion protein contacts the normal form of the protein", "Antibodies cover a virus's receptor-binding proteins", "A viral genome persists in host cells with limited gene expression" ], "answer": 3, "explanation": "Clinical symptoms may disappear while the infection remains. Latency minimizes particle production and immune detection until reactivation." }, { "id": "acellular-latent-virus-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a viral genome persists in host cells with limited gene expression, which explanation best links the change to its outcome?", "options": [ "Latency minimizes particle production and immune detection until reactivation", "Neutralization blocks the viral structures needed to recognize cellular receptors", "Interferon signalling induces antiviral proteins that inhibit genome copying and translation", "The abnormal conformation templates misfolding without using nucleic acid" ], "answer": 0, "explanation": "Clinical symptoms may disappear while the infection remains. Latency minimizes particle production and immune detection until reactivation." }, { "id": "acellular-interferon-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a virus-infected cell releases type I interferons, which observation is most likely?", "options": [ "Attachment and entry into host cells are reduced", "Nearby cells become more resistant to viral replication", "More proteins adopt the abnormal aggregation-prone shape", "Plant gene regulation and growth may be disrupted" ], "answer": 1, "explanation": "Nearby cells become more resistant to viral replication. Interferon signalling induces antiviral proteins that inhibit genome copying and translation." }, { "id": "acellular-interferon-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A learner records that nearby cells become more resistant to viral replication. Which preceding event best accounts for it?", "options": [ "Antibodies cover a virus's receptor-binding proteins", "A misfolded prion protein contacts the normal form of the protein", "A virus-infected cell releases type I interferons", "A small circular viroid RNA enters a susceptible plant" ], "answer": 2, "explanation": "Nearby cells become more resistant to viral replication. Interferon signalling induces antiviral proteins that inhibit genome copying and translation." }, { "id": "acellular-interferon-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a virus-infected cell releases type I interferons, which explanation best links the change to its outcome?", "options": [ "Neutralization blocks the viral structures needed to recognize cellular receptors", "The abnormal conformation templates misfolding without using nucleic acid", "The naked RNA interacts with host pathways despite encoding no capsid proteins", "Interferon signalling induces antiviral proteins that inhibit genome copying and translation" ], "answer": 3, "explanation": "Nearby cells become more resistant to viral replication. Interferon signalling induces antiviral proteins that inhibit genome copying and translation." }, { "id": "acellular-interferon-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a virus-infected cell releases type I interferons?", "options": [ "Nearby cells become more resistant to viral replication — Interferon signalling induces antiviral proteins that inhibit genome copying and translation", "Attachment and entry into host cells are reduced — Neutralization blocks the viral structures needed to recognize cellular receptors", "More proteins adopt the abnormal aggregation-prone shape — The abnormal conformation templates misfolding without using nucleic acid", "Plant gene regulation and growth may be disrupted — The naked RNA interacts with host pathways despite encoding no capsid proteins" ], "answer": 0, "explanation": "Nearby cells become more resistant to viral replication. Interferon signalling induces antiviral proteins that inhibit genome copying and translation." }, { "id": "acellular-neutralizing-antibody-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A student models this change: Antibodies cover a virus's receptor-binding proteins. What should the model predict first?", "options": [ "More proteins adopt the abnormal aggregation-prone shape", "Attachment and entry into host cells are reduced", "Plant gene regulation and growth may be disrupted", "Production of new viral genomes declines" ], "answer": 1, "explanation": "Attachment and entry into host cells are reduced. Neutralization blocks the viral structures needed to recognize cellular receptors." }, { "id": "acellular-neutralizing-antibody-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "What is the most likely cause when attachment and entry into host cells are reduced?", "options": [ "A misfolded prion protein contacts the normal form of the protein", "A small circular viroid RNA enters a susceptible plant", "Antibodies cover a virus's receptor-binding proteins", "A drug selectively inhibits an essential viral polymerase" ], "answer": 2, "explanation": "Attachment and entry into host cells are reduced. Neutralization blocks the viral structures needed to recognize cellular receptors." }, { "id": "acellular-neutralizing-antibody-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After antibodies cover a virus's receptor-binding proteins, which explanation best links the change to its outcome?", "options": [ "Genome replication cannot proceed normally while most host DNA enzymes remain unaffected", "The abnormal conformation templates misfolding without using nucleic acid", "The naked RNA interacts with host pathways despite encoding no capsid proteins", "Neutralization blocks the viral structures needed to recognize cellular receptors" ], "answer": 3, "explanation": "Attachment and entry into host cells are reduced. Neutralization blocks the viral structures needed to recognize cellular receptors." }, { "id": "acellular-neutralizing-antibody-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: antibodies cover a virus's receptor-binding proteins?", "options": [ "Attachment and entry into host cells are reduced — Neutralization blocks the viral structures needed to recognize cellular receptors", "More proteins adopt the abnormal aggregation-prone shape — The abnormal conformation templates misfolding without using nucleic acid", "Plant gene regulation and growth may be disrupted — The naked RNA interacts with host pathways despite encoding no capsid proteins", "Production of new viral genomes declines — Genome replication cannot proceed normally while most host DNA enzymes remain unaffected" ], "answer": 0, "explanation": "Attachment and entry into host cells are reduced. Neutralization blocks the viral structures needed to recognize cellular receptors." }, { "id": "acellular-prion-conversion-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: A misfolded prion protein contacts the normal form of the protein?", "options": [ "Plant gene regulation and growth may be disrupted", "More proteins adopt the abnormal aggregation-prone shape", "No complete infectious particles are briefly detectable inside the cell", "Production of new viral genomes declines" ], "answer": 1, "explanation": "More proteins adopt the abnormal aggregation-prone shape. The abnormal conformation templates misfolding without using nucleic acid." }, { "id": "acellular-prion-conversion-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: more proteins adopt the abnormal aggregation-prone shape?", "options": [ "A drug selectively inhibits an essential viral polymerase", "A small circular viroid RNA enters a susceptible plant", "A misfolded prion protein contacts the normal form of the protein", "A virus has entered and uncoated inside a host cell" ], "answer": 2, "explanation": "More proteins adopt the abnormal aggregation-prone shape. The abnormal conformation templates misfolding without using nucleic acid." }, { "id": "acellular-prion-conversion-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a misfolded prion protein contacts the normal form of the protein, which explanation best links the change to its outcome?", "options": [ "The naked RNA interacts with host pathways despite encoding no capsid proteins", "Parental virions are disassembled before newly synthesized parts have been assembled", "Genome replication cannot proceed normally while most host DNA enzymes remain unaffected", "The abnormal conformation templates misfolding without using nucleic acid" ], "answer": 3, "explanation": "More proteins adopt the abnormal aggregation-prone shape. The abnormal conformation templates misfolding without using nucleic acid." }, { "id": "acellular-prion-conversion-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a misfolded prion protein contacts the normal form of the protein?", "options": [ "More proteins adopt the abnormal aggregation-prone shape — The abnormal conformation templates misfolding without using nucleic acid", "Production of new viral genomes declines — Genome replication cannot proceed normally while most host DNA enzymes remain unaffected", "Plant gene regulation and growth may be disrupted — The naked RNA interacts with host pathways despite encoding no capsid proteins", "No complete infectious particles are briefly detectable inside the cell — Parental virions are disassembled before newly synthesized parts have been assembled" ], "answer": 0, "explanation": "More proteins adopt the abnormal aggregation-prone shape. The abnormal conformation templates misfolding without using nucleic acid." }, { "id": "acellular-viroid-rna-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A small circular viroid RNA enters a susceptible plant. Which outcome follows most directly?", "options": [ "Production of new viral genomes declines", "Plant gene regulation and growth may be disrupted", "No complete infectious particles are briefly detectable inside the cell", "Progeny may contain genome segments from both parental viruses" ], "answer": 1, "explanation": "Plant gene regulation and growth may be disrupted. The naked RNA interacts with host pathways despite encoding no capsid proteins." }, { "id": "acellular-viroid-rna-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which change most directly explains this observation: plant gene regulation and growth may be disrupted?", "options": [ "A drug selectively inhibits an essential viral polymerase", "A virus has entered and uncoated inside a host cell", "A small circular viroid RNA enters a susceptible plant", "Two related segmented viruses infect the same cell simultaneously" ], "answer": 2, "explanation": "Plant gene regulation and growth may be disrupted. The naked RNA interacts with host pathways despite encoding no capsid proteins." }, { "id": "acellular-viroid-rna-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a small circular viroid RNA enters a susceptible plant, which explanation best links the change to its outcome?", "options": [ "Genome replication cannot proceed normally while most host DNA enzymes remain unaffected", "Parental virions are disassembled before newly synthesized parts have been assembled", "Shared assembly machinery can package a reassorted combination of compatible segments", "The naked RNA interacts with host pathways despite encoding no capsid proteins" ], "answer": 3, "explanation": "Plant gene regulation and growth may be disrupted. The naked RNA interacts with host pathways despite encoding no capsid proteins." }, { "id": "acellular-viroid-rna-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a small circular viroid RNA enters a susceptible plant?", "options": [ "Plant gene regulation and growth may be disrupted — The naked RNA interacts with host pathways despite encoding no capsid proteins", "No complete infectious particles are briefly detectable inside the cell — Parental virions are disassembled before newly synthesized parts have been assembled", "Progeny may contain genome segments from both parental viruses — Shared assembly machinery can package a reassorted combination of compatible segments", "Production of new viral genomes declines — Genome replication cannot proceed normally while most host DNA enzymes remain unaffected" ], "answer": 0, "explanation": "Plant gene regulation and growth may be disrupted. The naked RNA interacts with host pathways despite encoding no capsid proteins." }, { "id": "acellular-viral-polymerase-target-outcome", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a drug selectively inhibits an essential viral polymerase, which observation is most likely?", "options": [ "No complete infectious particles are briefly detectable inside the cell", "Production of new viral genomes declines", "Progeny may contain genome segments from both parental viruses", "The host cell's normal gene function may be disrupted" ], "answer": 1, "explanation": "Production of new viral genomes declines. Genome replication cannot proceed normally while most host DNA enzymes remain unaffected." }, { "id": "acellular-viral-polymerase-target-cause", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "A learner records that production of new viral genomes declines. Which preceding event best accounts for it?", "options": [ "A virus has entered and uncoated inside a host cell", "Two related segmented viruses infect the same cell simultaneously", "A drug selectively inhibits an essential viral polymerase", "Integration inserts retroviral DNA into an essential host gene" ], "answer": 2, "explanation": "Production of new viral genomes declines. Genome replication cannot proceed normally while most host DNA enzymes remain unaffected." }, { "id": "acellular-viral-polymerase-target-mechanism", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "After a drug selectively inhibits an essential viral polymerase, which explanation best links the change to its outcome?", "options": [ "Parental virions are disassembled before newly synthesized parts have been assembled", "Shared assembly machinery can package a reassorted combination of compatible segments", "Insertional mutagenesis changes the coding sequence or its regulation", "Genome replication cannot proceed normally while most host DNA enzymes remain unaffected" ], "answer": 3, "explanation": "Production of new viral genomes declines. Genome replication cannot proceed normally while most host DNA enzymes remain unaffected." }, { "id": "acellular-viral-polymerase-target-integrated", "chapter": "Acellular Life", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a drug selectively inhibits an essential viral polymerase?", "options": [ "Production of new viral genomes declines — Genome replication cannot proceed normally while most host DNA enzymes remain unaffected", "No complete infectious particles are briefly detectable inside the cell — Parental virions are disassembled before newly synthesized parts have been assembled", "Progeny may contain genome segments from both parental viruses — Shared assembly machinery can package a reassorted combination of compatible segments", "The host cell's normal gene function may be disrupted — Insertional mutagenesis changes the coding sequence or its regulation" ], "answer": 0, "explanation": "Production of new viral genomes declines. Genome replication cannot proceed normally while most host DNA enzymes remain unaffected." }, { "id": "acellular-eclipse-period-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "A student models this change: A virus has entered and uncoated inside a host cell. What should the model predict first?", "options": [ "Progeny may contain genome segments from both parental viruses", "No complete infectious particles are briefly detectable inside the cell", "The host cell's normal gene function may be disrupted", "The viral population accumulates genetic variation rapidly" ], "answer": 1, "explanation": "No complete infectious particles are briefly detectable inside the cell. Parental virions are disassembled before newly synthesized parts have been assembled." }, { "id": "acellular-eclipse-period-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "What is the most likely cause when no complete infectious particles are briefly detectable inside the cell?", "options": [ "Two related segmented viruses infect the same cell simultaneously", "Integration inserts retroviral DNA into an essential host gene", "A virus has entered and uncoated inside a host cell", "An RNA virus polymerase lacks effective proofreading" ], "answer": 2, "explanation": "No complete infectious particles are briefly detectable inside the cell. Parental virions are disassembled before newly synthesized parts have been assembled." }, { "id": "acellular-eclipse-period-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After a virus has entered and uncoated inside a host cell, which explanation best links the change to its outcome?", "options": [ "Replication errors persist instead of being corrected before progeny genomes form", "Shared assembly machinery can package a reassorted combination of compatible segments", "Insertional mutagenesis changes the coding sequence or its regulation", "Parental virions are disassembled before newly synthesized parts have been assembled" ], "answer": 3, "explanation": "No complete infectious particles are briefly detectable inside the cell. Parental virions are disassembled before newly synthesized parts have been assembled." }, { "id": "acellular-multiplicity-reassortment-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: Two related segmented viruses infect the same cell simultaneously?", "options": [ "Progeny may contain genome segments from both parental viruses", "The viral population accumulates genetic variation rapidly", "Transmission chains are interrupted and susceptible people receive indirect protection", "The host cell's normal gene function may be disrupted" ], "answer": 0, "explanation": "Progeny may contain genome segments from both parental viruses. Shared assembly machinery can package a reassorted combination of compatible segments." }, { "id": "acellular-multiplicity-reassortment-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: progeny may contain genome segments from both parental viruses?", "options": [ "Integration inserts retroviral DNA into an essential host gene", "Two related segmented viruses infect the same cell simultaneously", "An RNA virus polymerase lacks effective proofreading", "A high proportion of a population becomes immune to a virus" ], "answer": 1, "explanation": "Progeny may contain genome segments from both parental viruses. Shared assembly machinery can package a reassorted combination of compatible segments." }, { "id": "acellular-multiplicity-reassortment-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After two related segmented viruses infect the same cell simultaneously, which explanation best links the change to its outcome?", "options": [ "Insertional mutagenesis changes the coding sequence or its regulation", "Replication errors persist instead of being corrected before progeny genomes form", "Shared assembly machinery can package a reassorted combination of compatible segments", "Infectious individuals encounter fewer hosts capable of sustaining further spread" ], "answer": 2, "explanation": "Progeny may contain genome segments from both parental viruses. Shared assembly machinery can package a reassorted combination of compatible segments." }, { "id": "acellular-multiplicity-reassortment-integrated", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: two related segmented viruses infect the same cell simultaneously?", "options": [ "The host cell's normal gene function may be disrupted — Insertional mutagenesis changes the coding sequence or its regulation", "The viral population accumulates genetic variation rapidly — Replication errors persist instead of being corrected before progeny genomes form", "Transmission chains are interrupted and susceptible people receive indirect protection — Infectious individuals encounter fewer hosts capable of sustaining further spread", "Progeny may contain genome segments from both parental viruses — Shared assembly machinery can package a reassorted combination of compatible segments" ], "answer": 3, "explanation": "Progeny may contain genome segments from both parental viruses. Shared assembly machinery can package a reassorted combination of compatible segments." }, { "id": "acellular-provirus-mutation-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Integration inserts retroviral DNA into an essential host gene. Which outcome follows most directly?", "options": [ "The host cell's normal gene function may be disrupted", "The viral population accumulates genetic variation rapidly", "Transmission chains are interrupted and susceptible people receive indirect protection", "Stable insertion of viral DNA into host chromosomes is reduced" ], "answer": 0, "explanation": "The host cell's normal gene function may be disrupted. Insertional mutagenesis changes the coding sequence or its regulation." }, { "id": "acellular-provirus-mutation-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which change most directly explains this observation: the host cell's normal gene function may be disrupted?", "options": [ "An RNA virus polymerase lacks effective proofreading", "Integration inserts retroviral DNA into an essential host gene", "A high proportion of a population becomes immune to a virus", "An effective integrase inhibitor is given early in HIV infection" ], "answer": 1, "explanation": "The host cell's normal gene function may be disrupted. Insertional mutagenesis changes the coding sequence or its regulation." }, { "id": "acellular-provirus-mutation-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After integration inserts retroviral DNA into an essential host gene, which explanation best links the change to its outcome?", "options": [ "Replication errors persist instead of being corrected before progeny genomes form", "Infectious individuals encounter fewer hosts capable of sustaining further spread", "Insertional mutagenesis changes the coding sequence or its regulation", "The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA" ], "answer": 2, "explanation": "The host cell's normal gene function may be disrupted. Insertional mutagenesis changes the coding sequence or its regulation." }, { "id": "acellular-provirus-mutation-integrated", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: integration inserts retroviral DNA into an essential host gene?", "options": [ "The viral population accumulates genetic variation rapidly — Replication errors persist instead of being corrected before progeny genomes form", "Transmission chains are interrupted and susceptible people receive indirect protection — Infectious individuals encounter fewer hosts capable of sustaining further spread", "Stable insertion of viral DNA into host chromosomes is reduced — The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "The host cell's normal gene function may be disrupted — Insertional mutagenesis changes the coding sequence or its regulation" ], "answer": 3, "explanation": "The host cell's normal gene function may be disrupted. Insertional mutagenesis changes the coding sequence or its regulation." }, { "id": "acellular-rna-error-rate-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After an RNA virus polymerase lacks effective proofreading, which observation is most likely?", "options": [ "The viral population accumulates genetic variation rapidly", "Transmission chains are interrupted and susceptible people receive indirect protection", "Stable insertion of viral DNA into host chromosomes is reduced", "The nucleic acid becomes better protected outside the host cell" ], "answer": 0, "explanation": "The viral population accumulates genetic variation rapidly. Replication errors persist instead of being corrected before progeny genomes form." }, { "id": "acellular-rna-error-rate-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "A learner records that the viral population accumulates genetic variation rapidly. Which preceding event best accounts for it?", "options": [ "A high proportion of a population becomes immune to a virus", "An RNA virus polymerase lacks effective proofreading", "An effective integrase inhibitor is given early in HIV infection", "A viral genome becomes enclosed by a complete capsid" ], "answer": 1, "explanation": "The viral population accumulates genetic variation rapidly. Replication errors persist instead of being corrected before progeny genomes form." }, { "id": "acellular-rna-error-rate-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After an RNA virus polymerase lacks effective proofreading, which explanation best links the change to its outcome?", "options": [ "Infectious individuals encounter fewer hosts capable of sustaining further spread", "The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "Replication errors persist instead of being corrected before progeny genomes form", "Capsid proteins shield the genome from nucleases and environmental damage" ], "answer": 2, "explanation": "The viral population accumulates genetic variation rapidly. Replication errors persist instead of being corrected before progeny genomes form." }, { "id": "acellular-rna-error-rate-integrated", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: an RNA virus polymerase lacks effective proofreading?", "options": [ "The nucleic acid becomes better protected outside the host cell — Capsid proteins shield the genome from nucleases and environmental damage", "Transmission chains are interrupted and susceptible people receive indirect protection — Infectious individuals encounter fewer hosts capable of sustaining further spread", "Stable insertion of viral DNA into host chromosomes is reduced — The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "The viral population accumulates genetic variation rapidly — Replication errors persist instead of being corrected before progeny genomes form" ], "answer": 3, "explanation": "The viral population accumulates genetic variation rapidly. Replication errors persist instead of being corrected before progeny genomes form." }, { "id": "acellular-herd-immunity-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "A student models this change: A high proportion of a population becomes immune to a virus. What should the model predict first?", "options": [ "Transmission chains are interrupted and susceptible people receive indirect protection", "The nucleic acid becomes better protected outside the host cell", "Stable insertion of viral DNA into host chromosomes is reduced", "The virus fails to infect that cell efficiently" ], "answer": 0, "explanation": "Transmission chains are interrupted and susceptible people receive indirect protection. Infectious individuals encounter fewer hosts capable of sustaining further spread." }, { "id": "acellular-herd-immunity-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "What is the most likely cause when transmission chains are interrupted and susceptible people receive indirect protection?", "options": [ "An effective integrase inhibitor is given early in HIV infection", "A high proportion of a population becomes immune to a virus", "A virus lacks a surface protein able to bind a cell's receptor", "A viral genome becomes enclosed by a complete capsid" ], "answer": 1, "explanation": "Transmission chains are interrupted and susceptible people receive indirect protection. Infectious individuals encounter fewer hosts capable of sustaining further spread." }, { "id": "acellular-herd-immunity-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After a high proportion of a population becomes immune to a virus, which explanation best links the change to its outcome?", "options": [ "Capsid proteins shield the genome from nucleases and environmental damage", "The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "Infectious individuals encounter fewer hosts capable of sustaining further spread", "Attachment requires molecular complementarity between viral ligands and host receptors" ], "answer": 2, "explanation": "Transmission chains are interrupted and susceptible people receive indirect protection. Infectious individuals encounter fewer hosts capable of sustaining further spread." }, { "id": "acellular-herd-immunity-integrated", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: a high proportion of a population becomes immune to a virus?", "options": [ "Stable insertion of viral DNA into host chromosomes is reduced — The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "The virus fails to infect that cell efficiently — Attachment requires molecular complementarity between viral ligands and host receptors", "The nucleic acid becomes better protected outside the host cell — Capsid proteins shield the genome from nucleases and environmental damage", "Transmission chains are interrupted and susceptible people receive indirect protection — Infectious individuals encounter fewer hosts capable of sustaining further spread" ], "answer": 3, "explanation": "Transmission chains are interrupted and susceptible people receive indirect protection. Infectious individuals encounter fewer hosts capable of sustaining further spread." }, { "id": "acellular-integration-inhibitor-outcome", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: An effective integrase inhibitor is given early in HIV infection?", "options": [ "Stable insertion of viral DNA into host chromosomes is reduced", "The virus fails to infect that cell efficiently", "It cannot independently synthesize proteins or reproduce", "The nucleic acid becomes better protected outside the host cell" ], "answer": 0, "explanation": "Stable insertion of viral DNA into host chromosomes is reduced. The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA." }, { "id": "acellular-integration-inhibitor-cause", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: stable insertion of viral DNA into host chromosomes is reduced?", "options": [ "A viral genome becomes enclosed by a complete capsid", "An effective integrase inhibitor is given early in HIV infection", "A virus lacks a surface protein able to bind a cell's receptor", "A virion remains outside a living host cell" ], "answer": 1, "explanation": "Stable insertion of viral DNA into host chromosomes is reduced. The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA." }, { "id": "acellular-integration-inhibitor-mechanism", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "After an effective integrase inhibitor is given early in HIV infection, which explanation best links the change to its outcome?", "options": [ "Capsid proteins shield the genome from nucleases and environmental damage", "Attachment requires molecular complementarity between viral ligands and host receptors", "The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA", "Viruses lack ribosomes and the complete metabolic machinery required for replication" ], "answer": 2, "explanation": "Stable insertion of viral DNA into host chromosomes is reduced. The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA." }, { "id": "acellular-integration-inhibitor-integrated", "chapter": "Acellular Life", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: an effective integrase inhibitor is given early in HIV infection?", "options": [ "The nucleic acid becomes better protected outside the host cell — Capsid proteins shield the genome from nucleases and environmental damage", "The virus fails to infect that cell efficiently — Attachment requires molecular complementarity between viral ligands and host receptors", "It cannot independently synthesize proteins or reproduce — Viruses lack ribosomes and the complete metabolic machinery required for replication", "Stable insertion of viral DNA into host chromosomes is reduced — The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA" ], "answer": 3, "explanation": "Stable insertion of viral DNA into host chromosomes is reduced. The drug blocks the enzyme that normally joins reverse-transcribed viral DNA to host DNA." }, { "chapter": "Acellular Life", "id": "applied-phage-burst", "difficulty": "Standard", "stem": "After unadsorbed phages are removed, 200 infected bacteria release 16,000 new infectious phages in one cycle. Assuming every infected cell lyses, what is the mean burst size?", "options": [ "80 phages per bacterium", "200 phages per bacterium", "8 phages per bacterium", "16,000 phages per bacterium" ], "answer": 0, "explanation": "Burst size is progeny released per infected cell: 16,000 ÷ 200 = 80. It is not the total number of particles in the culture." }, { "chapter": "Acellular Life", "id": "applied-viral-block", "difficulty": "Challenge", "stem": "A drug does not change the number of viral genomes inside cells just after entry, but it sharply reduces viral protein production. Which early step is most directly affected?", "options": [ "Attachment to receptors", "Translation of viral mRNA", "Release of mature virions", "Adsorption to the cell surface" ], "answer": 1, "explanation": "Comparable intracellular genome numbers indicate entry occurred. Reduced viral protein production points most directly to translation, although later replication can also fall as a consequence." }, { "chapter": "Acellular Life", "id": "applied-retrovirus-order", "difficulty": "Standard", "stem": "In the simplified retrovirus pathway, which enzyme performs step X?", "options": [ "DNA ligase", "RNA-dependent RNA polymerase", "Reverse transcriptase", "Restriction endonuclease" ], "answer": 2, "explanation": "Reverse transcriptase synthesizes DNA using viral RNA as a template. Integrase is involved later in inserting the DNA into the host genome.", "visual": { "kind": "flow", "caption": "Retrovirus information pathway", "nodes": [ "Viral RNA", "X", "Viral DNA", "Integration into host DNA" ] } }, { "chapter": "Acellular Life", "id": "applied-treatment-control", "difficulty": "Standard", "stem": "What does the table best support about this virus under the conditions tested?", "options": [ "Its genome must be DNA", "Its capsid is made of phospholipid only", "It reproduces outside living cells", "It contains a detergent-sensitive structure important for infectivity" ], "answer": 3, "explanation": "Detergent sensitivity supports a role for a lipid envelope in infection. These results alone do not identify the genome type or prove that the capsid consists of lipid.", "visual": { "kind": "table", "caption": "Equal virus samples; infectivity measured after treatment", "headers": [ "Treatment", "Relative infectious units" ], "rows": [ [ "Untreated", "100" ], [ "Detergent", "2" ], [ "Control buffer", "98" ] ] } } ] }