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AP Biology Chapter 21 Flashcards

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6385704531MacroevolutionEvolutionary change above species level.0
6385704532Microevolution.Evolutionary change within allele frequencies in species.1
6385704533Hardy-Weinberg EquationsUsed to calculate allele frequencies to determine if evolution is occuring.2
6385704534Allele Frequency Equationp + q = 13
6385704535pFrequency of dominant allele.4
6385704536qFrequency of recessive allele.5
6385704537Genotype Frequency Equationp^2 + 2pq + q^2 = 16
6385704538p^2Frequency of homozygous dominant individuals.7
63857045392pqFrequency of heterozygote individuals.8
6385704540q^2Frequency of homozygous recessive individuals.9
6385704541Hardy-Weinberg EquilibriumLarge population size, no gene flow (immigration/ emigration), no mutations, random mating, and no natural selection.10
6385704542Factors that Lead to a Change in Allele FrequencySmall population size (genetic drift), bottleneck, founder effect.11
6385704543Genetic DriftA process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next; effects are most pronounced in small populations.12
6385704544BottleneckGenetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions; typically, the surviving population is no longer genetically representative of the original population13
6385704545Founder EffectGenetic drift that occurs when a few individuals become isolated from a larger population whose gene pool composition is not reflective of that of the original population.14
6385704546Sexual SelectionAdaptive changes that lead to an increased ability to secure a mate.15
6385704547Sexual DimorphismA difference in secondary sexual characteristics between males and females of the same species (size, color, ornamentation, behavior).16
6385704548Natural SelectionOnly mechanism of evolution that leads to adaptation to environment.17
6385704549Directional SelectionA mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.18
6385704550Disruptive SelectionDescribes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.19
6385704551Stabilizing SelectionInstead of favoring individuals with extreme phenotypes, it favors the intermediate variants. It reduces phenotypic variation and maintains the status quo.20
6385704552DiploidyUnfavorable recessive alleles can "hide" in the population as heterozygotes. Only expressed when two heterozygotes have offspring.21
6385704553Balanced PolymorphismNatural selection maintains stable frequencies of two or more phenotypes in a population (heterozygote advantage).22
6385704554Genetic VariationDifferences among individuals in the composition of their genes or other DNA sequences.23
6385704555Gene FlowThe transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.24
6385704556Neutral VariationDifferences in DNA sequence that do not confer a selective advantage or disadvantage.25

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