Traits Affect Populations - Middle School Life Science
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What process reshuffles existing alleles to create new trait combinations?
What process reshuffles existing alleles to create new trait combinations?
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Genetic recombination during sexual reproduction. Meiosis and fertilization mix parental genes.
Genetic recombination during sexual reproduction. Meiosis and fertilization mix parental genes.
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What does fitness mean in evolutionary biology?
What does fitness mean in evolutionary biology?
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Relative reproductive success in a specific environment. Not strength or speed, but reproductive output.
Relative reproductive success in a specific environment. Not strength or speed, but reproductive output.
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Identify the correct explanation link: why does trait variation matter for selection?
Identify the correct explanation link: why does trait variation matter for selection?
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Selection can only change populations when individuals differ in traits. No variation means no differential survival or reproduction.
Selection can only change populations when individuals differ in traits. No variation means no differential survival or reproduction.
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Choose the best conclusion: antibiotic use kills most bacteria; a few resistant survive.
Choose the best conclusion: antibiotic use kills most bacteria; a few resistant survive.
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Resistance increases in the bacterial population. Survivors reproduce, passing resistance genes to offspring.
Resistance increases in the bacterial population. Survivors reproduce, passing resistance genes to offspring.
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Identify the population outcome: a new predator makes bright coloration easier to spot.
Identify the population outcome: a new predator makes bright coloration easier to spot.
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Bright coloration decreases in frequency over generations. Predation pressure selects against conspicuous individuals.
Bright coloration decreases in frequency over generations. Predation pressure selects against conspicuous individuals.
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Identify the population outcome: drought favors deeper roots in plants over time.
Identify the population outcome: drought favors deeper roots in plants over time.
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Average root depth increases in the population. Shallow-rooted plants die more, shifting the trait distribution.
Average root depth increases in the population. Shallow-rooted plants die more, shifting the trait distribution.
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Which option best describes disruptive selection?
Which option best describes disruptive selection?
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Both extreme traits are favored over the intermediate. Can split populations into two distinct forms.
Both extreme traits are favored over the intermediate. Can split populations into two distinct forms.
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Which option best describes directional selection?
Which option best describes directional selection?
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One extreme trait is favored, shifting the population average. Pushes trait distribution toward one end.
One extreme trait is favored, shifting the population average. Pushes trait distribution toward one end.
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Which option best describes stabilizing selection?
Which option best describes stabilizing selection?
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Intermediate traits are favored; extremes are selected against. Reduces variation by eliminating both extremes.
Intermediate traits are favored; extremes are selected against. Reduces variation by eliminating both extremes.
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What is gene flow?
What is gene flow?
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Movement of alleles into or out of a population by migration. Immigrants bring new alleles; emigrants remove them.
Movement of alleles into or out of a population by migration. Immigrants bring new alleles; emigrants remove them.
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Identify the correct claim: selection acts on individuals or populations?
Identify the correct claim: selection acts on individuals or populations?
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Selection acts on individuals; populations change over generations. Individuals die or reproduce; their traits accumulate in populations.
Selection acts on individuals; populations change over generations. Individuals die or reproduce; their traits accumulate in populations.
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Identify the most direct source of new genetic variation in a population.
Identify the most direct source of new genetic variation in a population.
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Mutations. DNA copying errors create new alleles and traits.
Mutations. DNA copying errors create new alleles and traits.
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What is gene flow?
What is gene flow?
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Movement of alleles into or out of a population via migration. Migration spreads genetic variation between populations.
Movement of alleles into or out of a population via migration. Migration spreads genetic variation between populations.
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What is genetic drift?
What is genetic drift?
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Random change in allele frequencies, strongest in small populations. Sampling error causes random fluctuations in gene pools.
Random change in allele frequencies, strongest in small populations. Sampling error causes random fluctuations in gene pools.
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Which process changes trait frequencies because of chance rather than advantage: genetic drift or natural selection?
Which process changes trait frequencies because of chance rather than advantage: genetic drift or natural selection?
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Genetic drift. Drift is random; selection favors beneficial traits.
Genetic drift. Drift is random; selection favors beneficial traits.
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Which statement best connects trait variation to selection: variation affects survival, or survival creates variation?
Which statement best connects trait variation to selection: variation affects survival, or survival creates variation?
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Variation affects survival and reproduction. Selection acts on existing variation, doesn't create it.
Variation affects survival and reproduction. Selection acts on existing variation, doesn't create it.
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Identify the population outcome if a heritable trait increases survival in the current environment.
Identify the population outcome if a heritable trait increases survival in the current environment.
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That trait becomes more common over generations. Selection increases frequency of beneficial heritable traits.
That trait becomes more common over generations. Selection increases frequency of beneficial heritable traits.
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Identify the population outcome if a trait is beneficial but not heritable (for example, a learned behavior).
Identify the population outcome if a trait is beneficial but not heritable (for example, a learned behavior).
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No consistent increase in that trait frequency across generations. Without inheritance, beneficial traits die with the individual.
No consistent increase in that trait frequency across generations. Without inheritance, beneficial traits die with the individual.
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Which type of selection is shown when one extreme trait value is favored and the mean shifts?
Which type of selection is shown when one extreme trait value is favored and the mean shifts?
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Directional selection. Population shifts toward the favored extreme value.
Directional selection. Population shifts toward the favored extreme value.
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Which type of selection is shown when intermediate trait values are favored and extremes are selected against?
Which type of selection is shown when intermediate trait values are favored and extremes are selected against?
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Stabilizing selection. Average individuals have highest fitness.
Stabilizing selection. Average individuals have highest fitness.
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Identify the best claim: individuals evolve or populations evolve over time?
Identify the best claim: individuals evolve or populations evolve over time?
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Populations evolve over time. Individuals don't evolve; their traits are fixed at birth.
Populations evolve over time. Individuals don't evolve; their traits are fixed at birth.
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Identify the most likely outcome if a new predator appears and darker coloration improves camouflage and is heritable.
Identify the most likely outcome if a new predator appears and darker coloration improves camouflage and is heritable.
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Frequency of darker coloration increases in the population. Better camouflage increases survival, spreading the trait.
Frequency of darker coloration increases in the population. Better camouflage increases survival, spreading the trait.
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Which evidence best supports selection on a trait: more offspring from one variant or equal offspring from all variants?
Which evidence best supports selection on a trait: more offspring from one variant or equal offspring from all variants?
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More offspring from one heritable variant. Differential reproduction is the mechanism of selection.
More offspring from one heritable variant. Differential reproduction is the mechanism of selection.
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What is fitness in biology?
What is fitness in biology?
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Relative reproductive success in a given environment. Higher fitness means more offspring survive to reproduce.
Relative reproductive success in a given environment. Higher fitness means more offspring survive to reproduce.
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What is an adaptation?
What is an adaptation?
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A heritable trait that increases fitness in a specific environment. Adaptations evolve because they improve survival and reproduction.
A heritable trait that increases fitness in a specific environment. Adaptations evolve because they improve survival and reproduction.
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