{ "chapter": "Evolution", "count": 100, "answerIndex": "zero-based", "notice": "Original practice items including related concept variants; not official examination questions.", "questions": [ { "id": "antibiotic-selection", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After antibiotic treatment, resistant bacteria become common. The most accurate explanation is that the antibiotic:", "options": [ "Selected resistant variants already present in the population", "Taught every bacterium how to resist", "Prevented all bacterial reproduction", "Converted viruses into bacteria" ], "answer": 0, "explanation": "Resistance variants arise before exposure through mutation or gene transfer. Antibiotic treatment removes susceptible competitors and increases the relative success of resistant cells." }, { "id": "homologous-structures", "chapter": "Evolution", "difficulty": "Standard", "stem": "The same underlying forelimb bone pattern in whales, bats and humans is strongest evidence for:", "options": [ "Identical present-day functions", "Common ancestry followed by divergent evolution", "Inheritance of acquired characters", "Absence of natural selection" ], "answer": 1, "explanation": "Homologous structures share an underlying developmental origin despite different functions, supporting descent from a common ancestor and later divergence." }, { "id": "hardy-weinberg-change", "chapter": "Evolution", "difficulty": "Challenge", "stem": "A large randomly mating population has no mutation, migration or selection. Which outcome is expected across generations?", "options": [ "Every recessive allele disappears", "All individuals become heterozygous", "Allele frequencies remain approximately constant", "Natural selection becomes stronger each generation" ], "answer": 2, "explanation": "These conditions approximate Hardy–Weinberg equilibrium, under which allele and genotype frequencies remain stable apart from sampling error." }, { "id": "founder-effect", "chapter": "Evolution", "difficulty": "Standard", "stem": "A few individuals colonise an isolated island and carry allele frequencies unlike the source population. This is an example of:", "options": [ "Artificial selection", "Convergent evolution", "Gene flow into a large population", "The founder effect" ], "answer": 3, "explanation": "A new population founded by a small sample may begin with unrepresentative allele frequencies, a form of genetic drift called the founder effect." }, { "id": "evolution-variation-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Mutation and sexual reproduction create heritable differences in a population. Which outcome follows most directly?", "options": [ "Individuals vary in traits on which selection can act", "Its allele tends to become more common over generations", "The population becomes better suited to its environment", "Changes and extinctions through geological time can be reconstructed" ], "answer": 0, "explanation": "Individuals vary in traits on which selection can act. New alleles and reshuffled allele combinations produce genetic diversity." }, { "id": "evolution-variation-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: individuals vary in traits on which selection can act?", "options": [ "A heritable trait improves survival and reproduction in one environment", "Mutation and sexual reproduction create heritable differences in a population", "Natural selection repeatedly favours a useful inherited characteristic", "Organisms are preserved in a dated sequence of rock layers" ], "answer": 1, "explanation": "Individuals vary in traits on which selection can act. New alleles and reshuffled allele combinations produce genetic diversity." }, { "id": "evolution-variation-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After mutation and sexual reproduction create heritable differences in a population, which explanation best links the change to its outcome?", "options": [ "Carriers contribute more offspring and allele copies to the next generation", "Differential reproductive success accumulates favourable alleles", "New alleles and reshuffled allele combinations produce genetic diversity", "Relative and radiometric dating place fossil forms in chronological order" ], "answer": 2, "explanation": "Individuals vary in traits on which selection can act. New alleles and reshuffled allele combinations produce genetic diversity." }, { "id": "evolution-selection-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After a heritable trait improves survival and reproduction in one environment, which observation is most likely?", "options": [ "The population becomes better suited to its environment", "Common ancestry is supported", "Changes and extinctions through geological time can be reconstructed", "Its allele tends to become more common over generations" ], "answer": 3, "explanation": "Its allele tends to become more common over generations. Carriers contribute more offspring and allele copies to the next generation." }, { "id": "evolution-selection-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "A learner records that its allele tends to become more common over generations. Which preceding event best accounts for it?", "options": [ "A heritable trait improves survival and reproduction in one environment", "Organisms are preserved in a dated sequence of rock layers", "Natural selection repeatedly favours a useful inherited characteristic", "Different species share the same underlying limb-bone arrangement" ], "answer": 0, "explanation": "Its allele tends to become more common over generations. Carriers contribute more offspring and allele copies to the next generation." }, { "id": "evolution-selection-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After a heritable trait improves survival and reproduction in one environment, which explanation best links the change to its outcome?", "options": [ "Differential reproductive success accumulates favourable alleles", "Carriers contribute more offspring and allele copies to the next generation", "The structure was inherited and modified for divergent functions", "Relative and radiometric dating place fossil forms in chronological order" ], "answer": 1, "explanation": "Its allele tends to become more common over generations. Carriers contribute more offspring and allele copies to the next generation." }, { "id": "evolution-selection-integrated", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a heritable trait improves survival and reproduction in one environment?", "options": [ "Changes and extinctions through geological time can be reconstructed — Relative and radiometric dating place fossil forms in chronological order", "The population becomes better suited to its environment — Differential reproductive success accumulates favourable alleles", "Its allele tends to become more common over generations — Carriers contribute more offspring and allele copies to the next generation", "Common ancestry is supported — The structure was inherited and modified for divergent functions" ], "answer": 2, "explanation": "Its allele tends to become more common over generations. Carriers contribute more offspring and allele copies to the next generation." }, { "id": "evolution-adaptation-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "A student models this change: Natural selection repeatedly favours a useful inherited characteristic. What should the model predict first?", "options": [ "Changes and extinctions through geological time can be reconstructed", "Common ancestry is supported", "Resistance becomes more common in later generations", "The population becomes better suited to its environment" ], "answer": 3, "explanation": "The population becomes better suited to its environment. Differential reproductive success accumulates favourable alleles." }, { "id": "evolution-adaptation-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "What is the most likely cause when the population becomes better suited to its environment?", "options": [ "Natural selection repeatedly favours a useful inherited characteristic", "Different species share the same underlying limb-bone arrangement", "An antibiotic kills susceptible bacteria but resistant variants survive", "Organisms are preserved in a dated sequence of rock layers" ], "answer": 0, "explanation": "The population becomes better suited to its environment. Differential reproductive success accumulates favourable alleles." }, { "id": "evolution-adaptation-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After natural selection repeatedly favours a useful inherited characteristic, which explanation best links the change to its outcome?", "options": [ "Relative and radiometric dating place fossil forms in chronological order", "Differential reproductive success accumulates favourable alleles", "The structure was inherited and modified for divergent functions", "Treatment creates differential survival rather than intentionally causing adaptive mutations" ], "answer": 1, "explanation": "The population becomes better suited to its environment. Differential reproductive success accumulates favourable alleles." }, { "id": "evolution-adaptation-integrated", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: natural selection repeatedly favours a useful inherited characteristic?", "options": [ "Changes and extinctions through geological time can be reconstructed — Relative and radiometric dating place fossil forms in chronological order", "Common ancestry is supported — The structure was inherited and modified for divergent functions", "The population becomes better suited to its environment — Differential reproductive success accumulates favourable alleles", "Resistance becomes more common in later generations — Treatment creates differential survival rather than intentionally causing adaptive mutations" ], "answer": 2, "explanation": "The population becomes better suited to its environment. Differential reproductive success accumulates favourable alleles." }, { "id": "evolution-fossils-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which immediate result is most consistent with this condition: Organisms are preserved in a dated sequence of rock layers?", "options": [ "Common ancestry is supported", "Resistance becomes more common in later generations", "The population mean shifts toward that extreme", "Changes and extinctions through geological time can be reconstructed" ], "answer": 3, "explanation": "Changes and extinctions through geological time can be reconstructed. Relative and radiometric dating place fossil forms in chronological order." }, { "id": "evolution-fossils-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which condition would most specifically produce this result: changes and extinctions through geological time can be reconstructed?", "options": [ "Organisms are preserved in a dated sequence of rock layers", "Different species share the same underlying limb-bone arrangement", "An antibiotic kills susceptible bacteria but resistant variants survive", "One extreme phenotype consistently has the highest fitness" ], "answer": 0, "explanation": "Changes and extinctions through geological time can be reconstructed. Relative and radiometric dating place fossil forms in chronological order." }, { "id": "evolution-fossils-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After organisms are preserved in a dated sequence of rock layers, which explanation best links the change to its outcome?", "options": [ "The structure was inherited and modified for divergent functions", "Relative and radiometric dating place fossil forms in chronological order", "Treatment creates differential survival rather than intentionally causing adaptive mutations", "Directional selection increases alleles associated with the favoured end of the range" ], "answer": 1, "explanation": "Changes and extinctions through geological time can be reconstructed. Relative and radiometric dating place fossil forms in chronological order." }, { "id": "evolution-fossils-integrated", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: organisms are preserved in a dated sequence of rock layers?", "options": [ "Common ancestry is supported — The structure was inherited and modified for divergent functions", "Resistance becomes more common in later generations — Treatment creates differential survival rather than intentionally causing adaptive mutations", "Changes and extinctions through geological time can be reconstructed — Relative and radiometric dating place fossil forms in chronological order", "The population mean shifts toward that extreme — Directional selection increases alleles associated with the favoured end of the range" ], "answer": 2, "explanation": "Changes and extinctions through geological time can be reconstructed. Relative and radiometric dating place fossil forms in chronological order." }, { "id": "evolution-homology-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Different species share the same underlying limb-bone arrangement. Which outcome follows most directly?", "options": [ "Variation narrows around the existing mean", "Resistance becomes more common in later generations", "The population mean shifts toward that extreme", "Common ancestry is supported" ], "answer": 3, "explanation": "Common ancestry is supported. The structure was inherited and modified for divergent functions." }, { "id": "evolution-homology-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: common ancestry is supported?", "options": [ "Different species share the same underlying limb-bone arrangement", "An antibiotic kills susceptible bacteria but resistant variants survive", "One extreme phenotype consistently has the highest fitness", "Intermediate phenotypes survive better than both extremes" ], "answer": 0, "explanation": "Common ancestry is supported. The structure was inherited and modified for divergent functions." }, { "id": "evolution-homology-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After different species share the same underlying limb-bone arrangement, which explanation best links the change to its outcome?", "options": [ "Treatment creates differential survival rather than intentionally causing adaptive mutations", "The structure was inherited and modified for divergent functions", "Directional selection increases alleles associated with the favoured end of the range", "Stabilizing selection removes alleles contributing to extreme trait values" ], "answer": 1, "explanation": "Common ancestry is supported. The structure was inherited and modified for divergent functions." }, { "id": "evolution-homology-integrated", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: different species share the same underlying limb-bone arrangement?", "options": [ "Resistance becomes more common in later generations — Treatment creates differential survival rather than intentionally causing adaptive mutations", "The population mean shifts toward that extreme — Directional selection increases alleles associated with the favoured end of the range", "Common ancestry is supported — The structure was inherited and modified for divergent functions", "Variation narrows around the existing mean — Stabilizing selection removes alleles contributing to extreme trait values" ], "answer": 2, "explanation": "Common ancestry is supported. The structure was inherited and modified for divergent functions." }, { "id": "evolution-antibiotic-outcome", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After an antibiotic kills susceptible bacteria but resistant variants survive, which observation is most likely?", "options": [ "The population mean shifts toward that extreme", "The trait distribution can become bimodal", "Variation narrows around the existing mean", "Resistance becomes more common in later generations" ], "answer": 3, "explanation": "Resistance becomes more common in later generations. Treatment creates differential survival rather than intentionally causing adaptive mutations." }, { "id": "evolution-antibiotic-cause", "chapter": "Evolution", "difficulty": "Foundation", "stem": "A learner records that resistance becomes more common in later generations. Which preceding event best accounts for it?", "options": [ "An antibiotic kills susceptible bacteria but resistant variants survive", "Intermediate phenotypes survive better than both extremes", "One extreme phenotype consistently has the highest fitness", "Both extreme phenotypes outperform intermediate individuals" ], "answer": 0, "explanation": "Resistance becomes more common in later generations. Treatment creates differential survival rather than intentionally causing adaptive mutations." }, { "id": "evolution-antibiotic-mechanism", "chapter": "Evolution", "difficulty": "Foundation", "stem": "After an antibiotic kills susceptible bacteria but resistant variants survive, which explanation best links the change to its outcome?", "options": [ "Directional selection increases alleles associated with the favoured end of the range", "Treatment creates differential survival rather than intentionally causing adaptive mutations", "Disruptive selection favours different adaptations at opposite ends of the range", "Stabilizing selection removes alleles contributing to extreme trait values" ], "answer": 1, "explanation": "Resistance becomes more common in later generations. Treatment creates differential survival rather than intentionally causing adaptive mutations." }, { "id": "evolution-antibiotic-integrated", "chapter": "Evolution", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: an antibiotic kills susceptible bacteria but resistant variants survive?", "options": [ "Variation narrows around the existing mean — Stabilizing selection removes alleles contributing to extreme trait values", "The population mean shifts toward that extreme — Directional selection increases alleles associated with the favoured end of the range", "Resistance becomes more common in later generations — Treatment creates differential survival rather than intentionally causing adaptive mutations", "The trait distribution can become bimodal — Disruptive selection favours different adaptations at opposite ends of the range" ], "answer": 2, "explanation": "Resistance becomes more common in later generations. Treatment creates differential survival rather than intentionally causing adaptive mutations." }, { "id": "evolution-directional-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "A student models this change: One extreme phenotype consistently has the highest fitness. What should the model predict first?", "options": [ "Variation narrows around the existing mean", "The trait distribution can become bimodal", "The trait can spread through the population", "The population mean shifts toward that extreme" ], "answer": 3, "explanation": "The population mean shifts toward that extreme. Directional selection increases alleles associated with the favoured end of the range." }, { "id": "evolution-directional-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "What is the most likely cause when the population mean shifts toward that extreme?", "options": [ "One extreme phenotype consistently has the highest fitness", "Both extreme phenotypes outperform intermediate individuals", "A display trait strongly increases mating success despite a survival cost", "Intermediate phenotypes survive better than both extremes" ], "answer": 0, "explanation": "The population mean shifts toward that extreme. Directional selection increases alleles associated with the favoured end of the range." }, { "id": "evolution-directional-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After one extreme phenotype consistently has the highest fitness, which explanation best links the change to its outcome?", "options": [ "Stabilizing selection removes alleles contributing to extreme trait values", "Directional selection increases alleles associated with the favoured end of the range", "Disruptive selection favours different adaptations at opposite ends of the range", "Reproductive advantage can outweigh reduced viability in total fitness" ], "answer": 1, "explanation": "The population mean shifts toward that extreme. Directional selection increases alleles associated with the favoured end of the range." }, { "id": "evolution-stabilizing-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Intermediate phenotypes survive better than both extremes?", "options": [ "The trait distribution can become bimodal", "The trait can spread through the population", "Variation narrows around the existing mean", "Alleles may be lost or fixed independently of fitness" ], "answer": 2, "explanation": "Variation narrows around the existing mean. Stabilizing selection removes alleles contributing to extreme trait values." }, { "id": "evolution-stabilizing-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: variation narrows around the existing mean?", "options": [ "Allele frequencies change through random sampling in a small population", "Both extreme phenotypes outperform intermediate individuals", "A display trait strongly increases mating success despite a survival cost", "Intermediate phenotypes survive better than both extremes" ], "answer": 3, "explanation": "Variation narrows around the existing mean. Stabilizing selection removes alleles contributing to extreme trait values." }, { "id": "evolution-stabilizing-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After intermediate phenotypes survive better than both extremes, which explanation best links the change to its outcome?", "options": [ "Stabilizing selection removes alleles contributing to extreme trait values", "Disruptive selection favours different adaptations at opposite ends of the range", "Reproductive advantage can outweigh reduced viability in total fitness", "Chance differences in which individuals reproduce have large proportional effects" ], "answer": 0, "explanation": "Variation narrows around the existing mean. Stabilizing selection removes alleles contributing to extreme trait values." }, { "id": "evolution-stabilizing-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: intermediate phenotypes survive better than both extremes?", "options": [ "The trait distribution can become bimodal — Disruptive selection favours different adaptations at opposite ends of the range", "Variation narrows around the existing mean — Stabilizing selection removes alleles contributing to extreme trait values", "The trait can spread through the population — Reproductive advantage can outweigh reduced viability in total fitness", "Alleles may be lost or fixed independently of fitness — Chance differences in which individuals reproduce have large proportional effects" ], "answer": 1, "explanation": "Variation narrows around the existing mean. Stabilizing selection removes alleles contributing to extreme trait values." }, { "id": "evolution-disruptive-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "Both extreme phenotypes outperform intermediate individuals. Which outcome follows most directly?", "options": [ "Alleles may be lost or fixed independently of fitness", "The trait can spread through the population", "The trait distribution can become bimodal", "Genetic diversity falls and allele frequencies may shift" ], "answer": 2, "explanation": "The trait distribution can become bimodal. Disruptive selection favours different adaptations at opposite ends of the range." }, { "id": "evolution-disruptive-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which change most directly explains this observation: the trait distribution can become bimodal?", "options": [ "A display trait strongly increases mating success despite a survival cost", "A population is suddenly reduced to a few random survivors", "Allele frequencies change through random sampling in a small population", "Both extreme phenotypes outperform intermediate individuals" ], "answer": 3, "explanation": "The trait distribution can become bimodal. Disruptive selection favours different adaptations at opposite ends of the range." }, { "id": "evolution-disruptive-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After both extreme phenotypes outperform intermediate individuals, which explanation best links the change to its outcome?", "options": [ "Disruptive selection favours different adaptations at opposite ends of the range", "Chance differences in which individuals reproduce have large proportional effects", "Reproductive advantage can outweigh reduced viability in total fitness", "The survivors carry only a non-representative sample of the original gene pool" ], "answer": 0, "explanation": "The trait distribution can become bimodal. Disruptive selection favours different adaptations at opposite ends of the range." }, { "id": "evolution-disruptive-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: both extreme phenotypes outperform intermediate individuals?", "options": [ "The trait can spread through the population — Reproductive advantage can outweigh reduced viability in total fitness", "The trait distribution can become bimodal — Disruptive selection favours different adaptations at opposite ends of the range", "Genetic diversity falls and allele frequencies may shift — The survivors carry only a non-representative sample of the original gene pool", "Alleles may be lost or fixed independently of fitness — Chance differences in which individuals reproduce have large proportional effects" ], "answer": 1, "explanation": "The trait distribution can become bimodal. Disruptive selection favours different adaptations at opposite ends of the range." }, { "id": "evolution-sexual-selection-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "After a display trait strongly increases mating success despite a survival cost, which observation is most likely?", "options": [ "Alleles may be lost or fixed independently of fitness", "Genetic diversity falls and allele frequencies may shift", "The trait can spread through the population", "Its allele frequencies differ by chance from the source population" ], "answer": 2, "explanation": "The trait can spread through the population. Reproductive advantage can outweigh reduced viability in total fitness." }, { "id": "evolution-sexual-selection-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "A learner records that the trait can spread through the population. Which preceding event best accounts for it?", "options": [ "Allele frequencies change through random sampling in a small population", "A population is suddenly reduced to a few random survivors", "A small group establishes a new isolated population", "A display trait strongly increases mating success despite a survival cost" ], "answer": 3, "explanation": "The trait can spread through the population. Reproductive advantage can outweigh reduced viability in total fitness." }, { "id": "evolution-sexual-selection-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After a display trait strongly increases mating success despite a survival cost, which explanation best links the change to its outcome?", "options": [ "Reproductive advantage can outweigh reduced viability in total fitness", "The survivors carry only a non-representative sample of the original gene pool", "The founders bring only a sample of the original population's alleles", "Chance differences in which individuals reproduce have large proportional effects" ], "answer": 0, "explanation": "The trait can spread through the population. Reproductive advantage can outweigh reduced viability in total fitness." }, { "id": "evolution-sexual-selection-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a display trait strongly increases mating success despite a survival cost?", "options": [ "Alleles may be lost or fixed independently of fitness — Chance differences in which individuals reproduce have large proportional effects", "The trait can spread through the population — Reproductive advantage can outweigh reduced viability in total fitness", "Genetic diversity falls and allele frequencies may shift — The survivors carry only a non-representative sample of the original gene pool", "Its allele frequencies differ by chance from the source population — The founders bring only a sample of the original population's alleles" ], "answer": 1, "explanation": "The trait can spread through the population. Reproductive advantage can outweigh reduced viability in total fitness." }, { "id": "evolution-genetic-drift-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "A student models this change: Allele frequencies change through random sampling in a small population. What should the model predict first?", "options": [ "Genetic diversity falls and allele frequencies may shift", "Its allele frequencies differ by chance from the source population", "Alleles may be lost or fixed independently of fitness", "Alleles move between gene pools and populations may become more similar" ], "answer": 2, "explanation": "Alleles may be lost or fixed independently of fitness. Chance differences in which individuals reproduce have large proportional effects." }, { "id": "evolution-genetic-drift-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "What is the most likely cause when alleles may be lost or fixed independently of fitness?", "options": [ "A population is suddenly reduced to a few random survivors", "A small group establishes a new isolated population", "Individuals migrate and reproduce in another population", "Allele frequencies change through random sampling in a small population" ], "answer": 3, "explanation": "Alleles may be lost or fixed independently of fitness. Chance differences in which individuals reproduce have large proportional effects." }, { "id": "evolution-genetic-drift-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After allele frequencies change through random sampling in a small population, which explanation best links the change to its outcome?", "options": [ "Chance differences in which individuals reproduce have large proportional effects", "The survivors carry only a non-representative sample of the original gene pool", "The founders bring only a sample of the original population's alleles", "Migrants contribute their gametes to the recipient population" ], "answer": 0, "explanation": "Alleles may be lost or fixed independently of fitness. Chance differences in which individuals reproduce have large proportional effects." }, { "id": "evolution-genetic-drift-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: allele frequencies change through random sampling in a small population?", "options": [ "Genetic diversity falls and allele frequencies may shift — The survivors carry only a non-representative sample of the original gene pool", "Alleles may be lost or fixed independently of fitness — Chance differences in which individuals reproduce have large proportional effects", "Its allele frequencies differ by chance from the source population — The founders bring only a sample of the original population's alleles", "Alleles move between gene pools and populations may become more similar — Migrants contribute their gametes to the recipient population" ], "answer": 1, "explanation": "Alleles may be lost or fixed independently of fitness. Chance differences in which individuals reproduce have large proportional effects." }, { "id": "evolution-bottleneck-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: A population is suddenly reduced to a few random survivors?", "options": [ "Its allele frequencies differ by chance from the source population", "Alleles move between gene pools and populations may become more similar", "Genetic diversity falls and allele frequencies may shift", "They can accumulate independent genetic differences" ], "answer": 2, "explanation": "Genetic diversity falls and allele frequencies may shift. The survivors carry only a non-representative sample of the original gene pool." }, { "id": "evolution-bottleneck-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: genetic diversity falls and allele frequencies may shift?", "options": [ "Two populations stop exchanging genes", "A small group establishes a new isolated population", "Individuals migrate and reproduce in another population", "A population is suddenly reduced to a few random survivors" ], "answer": 3, "explanation": "Genetic diversity falls and allele frequencies may shift. The survivors carry only a non-representative sample of the original gene pool." }, { "id": "evolution-bottleneck-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After a population is suddenly reduced to a few random survivors, which explanation best links the change to its outcome?", "options": [ "The survivors carry only a non-representative sample of the original gene pool", "The founders bring only a sample of the original population's alleles", "Migrants contribute their gametes to the recipient population", "Mutation, drift and selection act separately without homogenizing gene flow" ], "answer": 0, "explanation": "Genetic diversity falls and allele frequencies may shift. The survivors carry only a non-representative sample of the original gene pool." }, { "id": "evolution-bottleneck-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a population is suddenly reduced to a few random survivors?", "options": [ "Its allele frequencies differ by chance from the source population — The founders bring only a sample of the original population's alleles", "Genetic diversity falls and allele frequencies may shift — The survivors carry only a non-representative sample of the original gene pool", "Alleles move between gene pools and populations may become more similar — Migrants contribute their gametes to the recipient population", "They can accumulate independent genetic differences — Mutation, drift and selection act separately without homogenizing gene flow" ], "answer": 1, "explanation": "Genetic diversity falls and allele frequencies may shift. The survivors carry only a non-representative sample of the original gene pool." }, { "id": "evolution-founder-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "A small group establishes a new isolated population. Which outcome follows most directly?", "options": [ "They can accumulate independent genetic differences", "Alleles move between gene pools and populations may become more similar", "Its allele frequencies differ by chance from the source population", "Allopatric speciation may occur" ], "answer": 2, "explanation": "Its allele frequencies differ by chance from the source population. The founders bring only a sample of the original population's alleles." }, { "id": "evolution-founder-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which change most directly explains this observation: its allele frequencies differ by chance from the source population?", "options": [ "Individuals migrate and reproduce in another population", "A physical barrier divides one population for many generations", "Two populations stop exchanging genes", "A small group establishes a new isolated population" ], "answer": 3, "explanation": "Its allele frequencies differ by chance from the source population. The founders bring only a sample of the original population's alleles." }, { "id": "evolution-founder-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After a small group establishes a new isolated population, which explanation best links the change to its outcome?", "options": [ "The founders bring only a sample of the original population's alleles", "Mutation, drift and selection act separately without homogenizing gene flow", "Migrants contribute their gametes to the recipient population", "Geographic isolation permits divergence until reproductive isolation evolves" ], "answer": 0, "explanation": "Its allele frequencies differ by chance from the source population. The founders bring only a sample of the original population's alleles." }, { "id": "evolution-gene-flow-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "After individuals migrate and reproduce in another population, which observation is most likely?", "options": [ "They can accumulate independent genetic differences", "Alleles move between gene pools and populations may become more similar", "Allopatric speciation may occur", "Analogous traits with similar functions may evolve" ], "answer": 1, "explanation": "Alleles move between gene pools and populations may become more similar. Migrants contribute their gametes to the recipient population." }, { "id": "evolution-gene-flow-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "A learner records that alleles move between gene pools and populations may become more similar. Which preceding event best accounts for it?", "options": [ "Two populations stop exchanging genes", "A physical barrier divides one population for many generations", "Individuals migrate and reproduce in another population", "Unrelated lineages face similar environmental pressures" ], "answer": 2, "explanation": "Alleles move between gene pools and populations may become more similar. Migrants contribute their gametes to the recipient population." }, { "id": "evolution-gene-flow-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After individuals migrate and reproduce in another population, which explanation best links the change to its outcome?", "options": [ "Mutation, drift and selection act separately without homogenizing gene flow", "Geographic isolation permits divergence until reproductive isolation evolves", "Natural selection independently favours comparable solutions rather than shared ancestry", "Migrants contribute their gametes to the recipient population" ], "answer": 3, "explanation": "Alleles move between gene pools and populations may become more similar. Migrants contribute their gametes to the recipient population." }, { "id": "evolution-gene-flow-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: individuals migrate and reproduce in another population?", "options": [ "Alleles move between gene pools and populations may become more similar — Migrants contribute their gametes to the recipient population", "They can accumulate independent genetic differences — Mutation, drift and selection act separately without homogenizing gene flow", "Allopatric speciation may occur — Geographic isolation permits divergence until reproductive isolation evolves", "Analogous traits with similar functions may evolve — Natural selection independently favours comparable solutions rather than shared ancestry" ], "answer": 0, "explanation": "Alleles move between gene pools and populations may become more similar. Migrants contribute their gametes to the recipient population." }, { "id": "evolution-reproductive-isolation-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "A student models this change: Two populations stop exchanging genes. What should the model predict first?", "options": [ "Allopatric speciation may occur", "They can accumulate independent genetic differences", "Analogous traits with similar functions may evolve", "Their divergence time can be estimated" ], "answer": 1, "explanation": "They can accumulate independent genetic differences. Mutation, drift and selection act separately without homogenizing gene flow." }, { "id": "evolution-reproductive-isolation-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "What is the most likely cause when they can accumulate independent genetic differences?", "options": [ "A physical barrier divides one population for many generations", "Unrelated lineages face similar environmental pressures", "Two populations stop exchanging genes", "Neutral sequence differences accumulate between isolated lineages" ], "answer": 2, "explanation": "They can accumulate independent genetic differences. Mutation, drift and selection act separately without homogenizing gene flow." }, { "id": "evolution-reproductive-isolation-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After two populations stop exchanging genes, which explanation best links the change to its outcome?", "options": [ "A calibrated average substitution rate converts genetic distance into elapsed time", "Geographic isolation permits divergence until reproductive isolation evolves", "Natural selection independently favours comparable solutions rather than shared ancestry", "Mutation, drift and selection act separately without homogenizing gene flow" ], "answer": 3, "explanation": "They can accumulate independent genetic differences. Mutation, drift and selection act separately without homogenizing gene flow." }, { "id": "evolution-reproductive-isolation-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: two populations stop exchanging genes?", "options": [ "They can accumulate independent genetic differences — Mutation, drift and selection act separately without homogenizing gene flow", "Allopatric speciation may occur — Geographic isolation permits divergence until reproductive isolation evolves", "Analogous traits with similar functions may evolve — Natural selection independently favours comparable solutions rather than shared ancestry", "Their divergence time can be estimated — A calibrated average substitution rate converts genetic distance into elapsed time" ], "answer": 0, "explanation": "They can accumulate independent genetic differences. Mutation, drift and selection act separately without homogenizing gene flow." }, { "id": "evolution-allopatric-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: A physical barrier divides one population for many generations?", "options": [ "Analogous traits with similar functions may evolve", "Allopatric speciation may occur", "Allele and genotype frequencies remain approximately constant", "Their divergence time can be estimated" ], "answer": 1, "explanation": "Allopatric speciation may occur. Geographic isolation permits divergence until reproductive isolation evolves." }, { "id": "evolution-allopatric-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: allopatric speciation may occur?", "options": [ "Neutral sequence differences accumulate between isolated lineages", "Unrelated lineages face similar environmental pressures", "A physical barrier divides one population for many generations", "A large population mates randomly with no selection, mutation or migration" ], "answer": 2, "explanation": "Allopatric speciation may occur. Geographic isolation permits divergence until reproductive isolation evolves." }, { "id": "evolution-allopatric-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After a physical barrier divides one population for many generations, which explanation best links the change to its outcome?", "options": [ "Natural selection independently favours comparable solutions rather than shared ancestry", "The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift", "A calibrated average substitution rate converts genetic distance into elapsed time", "Geographic isolation permits divergence until reproductive isolation evolves" ], "answer": 3, "explanation": "Allopatric speciation may occur. Geographic isolation permits divergence until reproductive isolation evolves." }, { "id": "evolution-allopatric-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a physical barrier divides one population for many generations?", "options": [ "Allopatric speciation may occur — Geographic isolation permits divergence until reproductive isolation evolves", "Their divergence time can be estimated — A calibrated average substitution rate converts genetic distance into elapsed time", "Analogous traits with similar functions may evolve — Natural selection independently favours comparable solutions rather than shared ancestry", "Allele and genotype frequencies remain approximately constant — The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift" ], "answer": 0, "explanation": "Allopatric speciation may occur. Geographic isolation permits divergence until reproductive isolation evolves." }, { "id": "evolution-convergent-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "Unrelated lineages face similar environmental pressures. Which outcome follows most directly?", "options": [ "Their divergence time can be estimated", "Analogous traits with similar functions may evolve", "Allele and genotype frequencies remain approximately constant", "Its relative frequency tends to decline under selection" ], "answer": 1, "explanation": "Analogous traits with similar functions may evolve. Natural selection independently favours comparable solutions rather than shared ancestry." }, { "id": "evolution-convergent-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which change most directly explains this observation: analogous traits with similar functions may evolve?", "options": [ "Neutral sequence differences accumulate between isolated lineages", "A large population mates randomly with no selection, mutation or migration", "Unrelated lineages face similar environmental pressures", "One genotype leaves fewer viable offspring than another" ], "answer": 2, "explanation": "Analogous traits with similar functions may evolve. Natural selection independently favours comparable solutions rather than shared ancestry." }, { "id": "evolution-convergent-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After unrelated lineages face similar environmental pressures, which explanation best links the change to its outcome?", "options": [ "A calibrated average substitution rate converts genetic distance into elapsed time", "The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift", "Lower relative fitness reduces its proportional genetic contribution each generation", "Natural selection independently favours comparable solutions rather than shared ancestry" ], "answer": 3, "explanation": "Analogous traits with similar functions may evolve. Natural selection independently favours comparable solutions rather than shared ancestry." }, { "id": "evolution-convergent-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: unrelated lineages face similar environmental pressures?", "options": [ "Analogous traits with similar functions may evolve — Natural selection independently favours comparable solutions rather than shared ancestry", "Allele and genotype frequencies remain approximately constant — The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift", "Its relative frequency tends to decline under selection — Lower relative fitness reduces its proportional genetic contribution each generation", "Their divergence time can be estimated — A calibrated average substitution rate converts genetic distance into elapsed time" ], "answer": 0, "explanation": "Analogous traits with similar functions may evolve. Natural selection independently favours comparable solutions rather than shared ancestry." }, { "id": "evolution-molecular-clock-outcome", "chapter": "Evolution", "difficulty": "Standard", "stem": "After neutral sequence differences accumulate between isolated lineages, which observation is most likely?", "options": [ "Allele and genotype frequencies remain approximately constant", "Their divergence time can be estimated", "Its relative frequency tends to decline under selection", "Both alleles can remain in the population" ], "answer": 1, "explanation": "Their divergence time can be estimated. A calibrated average substitution rate converts genetic distance into elapsed time." }, { "id": "evolution-molecular-clock-cause", "chapter": "Evolution", "difficulty": "Standard", "stem": "A learner records that their divergence time can be estimated. Which preceding event best accounts for it?", "options": [ "A large population mates randomly with no selection, mutation or migration", "One genotype leaves fewer viable offspring than another", "Neutral sequence differences accumulate between isolated lineages", "Heterozygotes have higher fitness than either homozygote" ], "answer": 2, "explanation": "Their divergence time can be estimated. A calibrated average substitution rate converts genetic distance into elapsed time." }, { "id": "evolution-molecular-clock-mechanism", "chapter": "Evolution", "difficulty": "Standard", "stem": "After neutral sequence differences accumulate between isolated lineages, which explanation best links the change to its outcome?", "options": [ "The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift", "Lower relative fitness reduces its proportional genetic contribution each generation", "Balancing selection removes neither allele because each gains an advantage in heterozygotes", "A calibrated average substitution rate converts genetic distance into elapsed time" ], "answer": 3, "explanation": "Their divergence time can be estimated. A calibrated average substitution rate converts genetic distance into elapsed time." }, { "id": "evolution-molecular-clock-integrated", "chapter": "Evolution", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: neutral sequence differences accumulate between isolated lineages?", "options": [ "Their divergence time can be estimated — A calibrated average substitution rate converts genetic distance into elapsed time", "Allele and genotype frequencies remain approximately constant — The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift", "Its relative frequency tends to decline under selection — Lower relative fitness reduces its proportional genetic contribution each generation", "Both alleles can remain in the population — Balancing selection removes neither allele because each gains an advantage in heterozygotes" ], "answer": 0, "explanation": "Their divergence time can be estimated. A calibrated average substitution rate converts genetic distance into elapsed time." }, { "id": "evolution-hardy-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "A student models this change: A large population mates randomly with no selection, mutation or migration. What should the model predict first?", "options": [ "Its relative frequency tends to decline under selection", "Allele and genotype frequencies remain approximately constant", "Both alleles can remain in the population", "Multiple species with distinct adaptations can evolve rapidly" ], "answer": 1, "explanation": "Allele and genotype frequencies remain approximately constant. The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift." }, { "id": "evolution-hardy-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "What is the most likely cause when allele and genotype frequencies remain approximately constant?", "options": [ "One genotype leaves fewer viable offspring than another", "Heterozygotes have higher fitness than either homozygote", "A large population mates randomly with no selection, mutation or migration", "One ancestral lineage enters several underused ecological niches" ], "answer": 2, "explanation": "Allele and genotype frequencies remain approximately constant. The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift." }, { "id": "evolution-hardy-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After a large population mates randomly with no selection, mutation or migration, which explanation best links the change to its outcome?", "options": [ "Divergent selection favours specialized forms as populations exploit different resources", "Lower relative fitness reduces its proportional genetic contribution each generation", "Balancing selection removes neither allele because each gains an advantage in heterozygotes", "The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift" ], "answer": 3, "explanation": "Allele and genotype frequencies remain approximately constant. The Hardy-Weinberg conditions prevent systematic evolutionary forces and minimize drift." }, { "id": "evolution-selection-coefficient-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: One genotype leaves fewer viable offspring than another?", "options": [ "Its relative frequency tends to decline under selection", "Multiple species with distinct adaptations can evolve rapidly", "Selection favours parasites able to overcome that defence", "Both alleles can remain in the population" ], "answer": 0, "explanation": "Its relative frequency tends to decline under selection. Lower relative fitness reduces its proportional genetic contribution each generation." }, { "id": "evolution-selection-coefficient-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: its relative frequency tends to decline under selection?", "options": [ "Heterozygotes have higher fitness than either homozygote", "One genotype leaves fewer viable offspring than another", "One ancestral lineage enters several underused ecological niches", "A host evolves a defence that reduces parasite success" ], "answer": 1, "explanation": "Its relative frequency tends to decline under selection. Lower relative fitness reduces its proportional genetic contribution each generation." }, { "id": "evolution-selection-coefficient-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After one genotype leaves fewer viable offspring than another, which explanation best links the change to its outcome?", "options": [ "Balancing selection removes neither allele because each gains an advantage in heterozygotes", "Divergent selection favours specialized forms as populations exploit different resources", "Lower relative fitness reduces its proportional genetic contribution each generation", "Reciprocal selective pressures drive continuing change in interacting species" ], "answer": 2, "explanation": "Its relative frequency tends to decline under selection. Lower relative fitness reduces its proportional genetic contribution each generation." }, { "id": "evolution-selection-coefficient-integrated", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: one genotype leaves fewer viable offspring than another?", "options": [ "Both alleles can remain in the population — Balancing selection removes neither allele because each gains an advantage in heterozygotes", "Multiple species with distinct adaptations can evolve rapidly — Divergent selection favours specialized forms as populations exploit different resources", "Selection favours parasites able to overcome that defence — Reciprocal selective pressures drive continuing change in interacting species", "Its relative frequency tends to decline under selection — Lower relative fitness reduces its proportional genetic contribution each generation" ], "answer": 3, "explanation": "Its relative frequency tends to decline under selection. Lower relative fitness reduces its proportional genetic contribution each generation." }, { "id": "evolution-heterozygote-advantage-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Heterozygotes have higher fitness than either homozygote. Which outcome follows most directly?", "options": [ "Both alleles can remain in the population", "Multiple species with distinct adaptations can evolve rapidly", "Selection favours parasites able to overcome that defence", "Its frequency changes mainly through genetic drift" ], "answer": 0, "explanation": "Both alleles can remain in the population. Balancing selection removes neither allele because each gains an advantage in heterozygotes." }, { "id": "evolution-heterozygote-advantage-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which change most directly explains this observation: both alleles can remain in the population?", "options": [ "One ancestral lineage enters several underused ecological niches", "Heterozygotes have higher fitness than either homozygote", "A host evolves a defence that reduces parasite success", "A new allele has little or no effect on reproductive fitness" ], "answer": 1, "explanation": "Both alleles can remain in the population. Balancing selection removes neither allele because each gains an advantage in heterozygotes." }, { "id": "evolution-heterozygote-advantage-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After heterozygotes have higher fitness than either homozygote, which explanation best links the change to its outcome?", "options": [ "Divergent selection favours specialized forms as populations exploit different resources", "Reciprocal selective pressures drive continuing change in interacting species", "Balancing selection removes neither allele because each gains an advantage in heterozygotes", "Without consistent selection, chance sampling determines its long-term fate" ], "answer": 2, "explanation": "Both alleles can remain in the population. Balancing selection removes neither allele because each gains an advantage in heterozygotes." }, { "id": "evolution-heterozygote-advantage-integrated", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: heterozygotes have higher fitness than either homozygote?", "options": [ "Multiple species with distinct adaptations can evolve rapidly — Divergent selection favours specialized forms as populations exploit different resources", "Selection favours parasites able to overcome that defence — Reciprocal selective pressures drive continuing change in interacting species", "Its frequency changes mainly through genetic drift — Without consistent selection, chance sampling determines its long-term fate", "Both alleles can remain in the population — Balancing selection removes neither allele because each gains an advantage in heterozygotes" ], "answer": 3, "explanation": "Both alleles can remain in the population. Balancing selection removes neither allele because each gains an advantage in heterozygotes." }, { "id": "evolution-adaptive-radiation-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After one ancestral lineage enters several underused ecological niches, which observation is most likely?", "options": [ "Multiple species with distinct adaptations can evolve rapidly", "Selection favours parasites able to overcome that defence", "Its frequency changes mainly through genetic drift", "Individuals vary in traits on which selection can act" ], "answer": 0, "explanation": "Multiple species with distinct adaptations can evolve rapidly. Divergent selection favours specialized forms as populations exploit different resources." }, { "id": "evolution-adaptive-radiation-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "A learner records that multiple species with distinct adaptations can evolve rapidly. Which preceding event best accounts for it?", "options": [ "A host evolves a defence that reduces parasite success", "One ancestral lineage enters several underused ecological niches", "A new allele has little or no effect on reproductive fitness", "Mutation and sexual reproduction create heritable differences in a population" ], "answer": 1, "explanation": "Multiple species with distinct adaptations can evolve rapidly. Divergent selection favours specialized forms as populations exploit different resources." }, { "id": "evolution-adaptive-radiation-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After one ancestral lineage enters several underused ecological niches, which explanation best links the change to its outcome?", "options": [ "Reciprocal selective pressures drive continuing change in interacting species", "Without consistent selection, chance sampling determines its long-term fate", "Divergent selection favours specialized forms as populations exploit different resources", "New alleles and reshuffled allele combinations produce genetic diversity" ], "answer": 2, "explanation": "Multiple species with distinct adaptations can evolve rapidly. Divergent selection favours specialized forms as populations exploit different resources." }, { "id": "evolution-adaptive-radiation-integrated", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: one ancestral lineage enters several underused ecological niches?", "options": [ "Individuals vary in traits on which selection can act — New alleles and reshuffled allele combinations produce genetic diversity", "Selection favours parasites able to overcome that defence — Reciprocal selective pressures drive continuing change in interacting species", "Its frequency changes mainly through genetic drift — Without consistent selection, chance sampling determines its long-term fate", "Multiple species with distinct adaptations can evolve rapidly — Divergent selection favours specialized forms as populations exploit different resources" ], "answer": 3, "explanation": "Multiple species with distinct adaptations can evolve rapidly. Divergent selection favours specialized forms as populations exploit different resources." }, { "id": "evolution-coevolution-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "A student models this change: A host evolves a defence that reduces parasite success. What should the model predict first?", "options": [ "Selection favours parasites able to overcome that defence", "Individuals vary in traits on which selection can act", "Its frequency changes mainly through genetic drift", "Its allele tends to become more common over generations" ], "answer": 0, "explanation": "Selection favours parasites able to overcome that defence. Reciprocal selective pressures drive continuing change in interacting species." }, { "id": "evolution-coevolution-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "What is the most likely cause when selection favours parasites able to overcome that defence?", "options": [ "A new allele has little or no effect on reproductive fitness", "A host evolves a defence that reduces parasite success", "A heritable trait improves survival and reproduction in one environment", "Mutation and sexual reproduction create heritable differences in a population" ], "answer": 1, "explanation": "Selection favours parasites able to overcome that defence. Reciprocal selective pressures drive continuing change in interacting species." }, { "id": "evolution-coevolution-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After a host evolves a defence that reduces parasite success, which explanation best links the change to its outcome?", "options": [ "New alleles and reshuffled allele combinations produce genetic diversity", "Without consistent selection, chance sampling determines its long-term fate", "Reciprocal selective pressures drive continuing change in interacting species", "Carriers contribute more offspring and allele copies to the next generation" ], "answer": 2, "explanation": "Selection favours parasites able to overcome that defence. Reciprocal selective pressures drive continuing change in interacting species." }, { "id": "evolution-coevolution-integrated", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: a host evolves a defence that reduces parasite success?", "options": [ "Its frequency changes mainly through genetic drift — Without consistent selection, chance sampling determines its long-term fate", "Its allele tends to become more common over generations — Carriers contribute more offspring and allele copies to the next generation", "Individuals vary in traits on which selection can act — New alleles and reshuffled allele combinations produce genetic diversity", "Selection favours parasites able to overcome that defence — Reciprocal selective pressures drive continuing change in interacting species" ], "answer": 3, "explanation": "Selection favours parasites able to overcome that defence. Reciprocal selective pressures drive continuing change in interacting species." }, { "id": "evolution-neutral-theory-outcome", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: A new allele has little or no effect on reproductive fitness?", "options": [ "Its frequency changes mainly through genetic drift", "Its allele tends to become more common over generations", "The population becomes better suited to its environment", "Individuals vary in traits on which selection can act" ], "answer": 0, "explanation": "Its frequency changes mainly through genetic drift. Without consistent selection, chance sampling determines its long-term fate." }, { "id": "evolution-neutral-theory-cause", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: its frequency changes mainly through genetic drift?", "options": [ "Mutation and sexual reproduction create heritable differences in a population", "A new allele has little or no effect on reproductive fitness", "A heritable trait improves survival and reproduction in one environment", "Natural selection repeatedly favours a useful inherited characteristic" ], "answer": 1, "explanation": "Its frequency changes mainly through genetic drift. Without consistent selection, chance sampling determines its long-term fate." }, { "id": "evolution-neutral-theory-mechanism", "chapter": "Evolution", "difficulty": "Challenge", "stem": "After a new allele has little or no effect on reproductive fitness, which explanation best links the change to its outcome?", "options": [ "New alleles and reshuffled allele combinations produce genetic diversity", "Carriers contribute more offspring and allele copies to the next generation", "Without consistent selection, chance sampling determines its long-term fate", "Differential reproductive success accumulates favourable alleles" ], "answer": 2, "explanation": "Its frequency changes mainly through genetic drift. Without consistent selection, chance sampling determines its long-term fate." }, { "id": "evolution-neutral-theory-integrated", "chapter": "Evolution", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: a new allele has little or no effect on reproductive fitness?", "options": [ "Individuals vary in traits on which selection can act — New alleles and reshuffled allele combinations produce genetic diversity", "Its allele tends to become more common over generations — Carriers contribute more offspring and allele copies to the next generation", "The population becomes better suited to its environment — Differential reproductive success accumulates favourable alleles", "Its frequency changes mainly through genetic drift — Without consistent selection, chance sampling determines its long-term fate" ], "answer": 3, "explanation": "Its frequency changes mainly through genetic drift. Without consistent selection, chance sampling determines its long-term fate." }, { "chapter": "Evolution", "id": "applied-resistance-origin", "difficulty": "Standard", "stem": "Antibiotic-resistant colonies appear after a bacterial population is exposed to an antibiotic. Which additional observation most strongly supports selection of pre-existing resistance?", "options": [ "Resistant variants were detectable in the population before treatment", "All bacteria were larger after treatment", "The antibiotic changed colour", "Only treated cultures were ever examined" ], "answer": 0, "explanation": "Detecting resistance before exposure supports variation preceding selection. Antibiotic treatment then favours resistant survivors; it need not create the particular adaptive variant." }, { "chapter": "Evolution", "id": "applied-allele-frequency", "difficulty": "Standard", "stem": "A population contains 30 AA, 50 Aa and 20 aa individuals. What is the frequency of allele A?", "options": [ "0.30", "0.55", "0.50", "0.80" ], "answer": 1, "explanation": "There are 200 alleles at this locus. A alleles total 2×30 + 50 = 110, so their frequency is 110/200 = 0.55." }, { "chapter": "Evolution", "id": "applied-drift-evidence", "difficulty": "Challenge", "stem": "Two small isolated populations start with the same allele frequencies. With no consistent fitness differences, their frequencies diverge randomly over generations. The most direct explanation is:", "options": [ "Directional selection in the same direction", "Identical gene flow into both populations", "Genetic drift", "A purposeful response to environmental need" ], "answer": 2, "explanation": "Chance differences in which individuals reproduce can change allele frequencies, especially in small populations. This is genetic drift rather than a directed response to need." }, { "chapter": "Evolution", "id": "applied-fitness-count", "difficulty": "Standard", "stem": "In the same environment, which genotype has the highest measured reproductive contribution in this sample?", "options": [ "P, because it has the most adults", "The data show only mutation rates", "R, because all genotypes must have equal fitness", "Q, because it leaves the most surviving offspring per adult" ], "answer": 3, "explanation": "Relative contribution per adult is 2 for P, 3 for Q and 1 for R. Q is highest by this measure; body size or adult abundance alone would not establish it.", "visual": { "kind": "table", "caption": "Same observation period", "headers": [ "Genotype", "Adults", "Surviving offspring" ], "rows": [ [ "P", "20", "40" ], [ "Q", "10", "30" ], [ "R", "15", "15" ] ] } } ] }