Biology Flashcards: Evaluate Evidence For Population Change

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This deck focuses on Evaluate Evidence For Population Change, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: In Hardy–Weinberg terms, what does $q$ represent?

Answer: Frequency of the recessive allele. Conventionally represents the less common or recessive allele frequency.

Flashcard 2: Which type of selection favors one extreme phenotype and shifts the mean?

Answer: Directional selection. Population mean moves toward one end of the trait distribution.

Flashcard 3: Which selection pattern is indicated when the average phenotype becomes more common over time?

Answer: Stabilizing selection. Selection against extremes increases frequency of intermediate phenotypes.

Flashcard 4: A trait has $p = 0.9$; what is the expected frequency of the recessive allele?

Answer: $q = 0.1$. Allele frequencies must sum to 1, so $q = 1 - 0.9$.

Flashcard 5: Which evidence for evolution compares structures with similar anatomy due to common ancestry?

Answer: Homologous structures. Same underlying structure from common ancestor, modified for different functions.

Flashcard 6: Which mechanism is most consistent with random allele loss after a population bottleneck?

Answer: Genetic drift. Population bottlenecks reduce size, increasing random sampling effects.

Flashcard 7: Which selection pattern is indicated when one extreme phenotype increases in frequency over time?

Answer: Directional selection. One extreme has higher fitness, shifting the population mean.

Flashcard 8: In Hardy–Weinberg terms, what does $p$ represent?

Answer: Frequency of the dominant allele. Conventionally represents the more common or dominant allele frequency.

Flashcard 9: What are the five conditions required for Hardy–Weinberg equilibrium?

Answer: No selection, no mutation, no migration, random mating, very large $N$. These conditions prevent allele frequency changes, maintaining equilibrium.

Flashcard 10: Which type of selection favors intermediate phenotypes and reduces extremes?

Answer: Stabilizing selection. Average trait values are preserved while extremes are eliminated.

Flashcard 11: What is fitness in evolutionary biology?

Answer: Relative reproductive success of a genotype or phenotype. Measured by survival and reproductive output compared to other genotypes.

Flashcard 12: Identify the evolutionary mechanism that changes allele frequencies by chance in small populations.

Answer: Genetic drift. Random sampling effects are strongest when population size is limited.

Flashcard 13: Which result best supports natural selection if a heritable trait increases survival and becomes common?

Answer: Trait-associated alleles increase in frequency over time. Higher survival leads to increased reproduction and allele transmission.

Flashcard 14: In Hardy–Weinberg terms, what does $q$ represent?

Answer: Frequency of the recessive allele. Conventionally represents the less common or recessive allele frequency.

Flashcard 15: A population has $p = 0.4$; what is the expected homozygous recessive frequency?

Answer: $q^2 = 0.36$. If $p = 0.4$, then $q = 0.6$, so $q^2 = 0.36$.

Flashcard 16: Find the homozygous dominant genotype frequency if $p = 0.6$.

Answer: $p^2 = 0.36$. Square the dominant allele frequency: $0.6^2$.

Flashcard 17: Identify the evolutionary mechanism that moves alleles between populations.

Answer: Gene flow (migration). Movement of individuals carries alleles between separate populations.

Flashcard 18: Which result best supports natural selection if a heritable trait increases survival and becomes common?

Answer: Trait-associated alleles increase in frequency over time. Higher survival leads to increased reproduction and allele transmission.

Flashcard 19: Which mechanism is most consistent with increased allele mixing after individuals immigrate?

Answer: Gene flow. Immigration introduces new alleles and increases genetic mixing.

Flashcard 20: Which selection pattern is indicated when both extremes increase and intermediates decrease?

Answer: Disruptive selection. Intermediates have lower fitness than either extreme phenotype.

Flashcard 21: Which evidence for evolution is based on shared early developmental patterns among species?

Answer: Comparative embryology. Early developmental similarities reveal shared ancestry despite adult differences.

Flashcard 22: A trait has $q^2 = 0.04$; what is the expected heterozygote frequency $2pq$?

Answer: $2pq = 0.32$. If $q^2 = 0.04$, then $q = 0.2$, $p = 0.8$, so $2pq = 0.32$.

Flashcard 23: Which outcome indicates a population is evolving when compared to Hardy–Weinberg expectations?

Answer: Observed genotype frequencies differ from expected frequencies. Deviations from Hardy-Weinberg predictions indicate evolutionary forces acting.

Flashcard 24: Which observation best supports genetic drift if allele frequencies change without fitness differences?

Answer: Random allele frequency shifts, strongest in small populations. Random changes are more pronounced in smaller population sizes.

Flashcard 25: What is the definition of a species using the biological species concept?

Answer: Groups that interbreed and produce fertile offspring. Reproductive compatibility determines species boundaries in this concept.

Flashcard 26: Which genotype frequency corresponds to homozygous dominant under Hardy–Weinberg?

Answer: $p^2$. Probability of getting dominant allele from both parents equals $p \times p$.

Flashcard 27: Find the homozygous recessive genotype frequency if $q = 0.1$.

Answer: $q^2 = 0.01$. Square the recessive allele frequency: $0.1^2$.

Flashcard 28: What is the definition of a population in biology?

Answer: Interbreeding members of the same species in one area. Geographic boundaries define the scope of genetic exchange.

Flashcard 29: Calculate $p$ if the recessive phenotype frequency is $q^2 = 0.09$.

Answer: $p = 0.7$. If $q^2 = 0.09$, then $q = 0.3$ and $p = 1 - 0.3 = 0.7$.

Flashcard 30: Which genotype frequency corresponds to homozygous recessive under Hardy–Weinberg?

Answer: $q^2$. Probability of getting recessive allele from both parents equals $q \times q$.

Flashcard 31: Which genotype frequency corresponds to homozygous dominant under Hardy–Weinberg?

Answer: $p^2$. Probability of getting dominant allele from both parents equals $p \times p$.

Flashcard 32: Which evidence best supports common ancestry if two species share many identical DNA sequences?

Answer: High DNA sequence similarity (molecular homology). Genetic similarity indicates recent divergence from common ancestor.

Flashcard 33: A trait has $p = 0.9$; what is the expected frequency of the recessive allele?

Answer: $q = 0.1$. Allele frequencies must sum to 1, so $q = 1 - 0.9$.

Flashcard 34: Which conclusion is best supported if a trait is heritable and individuals with it leave more offspring?

Answer: Natural selection can increase the trait's allele frequency. Heritable traits under selection will increase in frequency over generations.

Flashcard 35: Find the expected heterozygote frequency if $p = 0.5$ and $q = 0.5$.

Answer: $2pq = 0.5$. When allele frequencies are equal, heterozygotes reach maximum frequency.

Flashcard 36: Which evidence best supports convergent evolution if two unrelated species share similar functions but not ancestry?

Answer: Analogous structures. Similar function without shared ancestry indicates independent evolution.

Flashcard 37: Which selection pattern is indicated when both extremes increase and intermediates decrease?

Answer: Disruptive selection. Intermediates have lower fitness than either extreme phenotype.

Flashcard 38: Which observation best supports genetic drift if allele frequencies change without fitness differences?

Answer: Random allele frequency shifts, strongest in small populations. Random changes are more pronounced in smaller population sizes.

Flashcard 39: Which comparison best supports descent with modification if forelimb bones match across mammals?

Answer: Homologous structures. Same bone pattern across species indicates common ancestral structure.

Flashcard 40: Identify the evolutionary mechanism that introduces new alleles by DNA change.

Answer: Mutation. DNA errors during replication create novel alleles in populations.

Flashcard 41: Find the heterozygote frequency if $p = 0.7$ and $q = 0.3$.

Answer: $2pq = 0.42$. Multiply $2 \times 0.7 \times 0.3$ to get heterozygote frequency.

Flashcard 42: A trait has $q^2 = 0.04$; what is the expected heterozygote frequency $2pq$?

Answer: $2pq = 0.32$. If $q^2 = 0.04$, then $q = 0.2$, $p = 0.8$, so $2pq = 0.32$.

Flashcard 43: Which comparison best supports descent with modification if forelimb bones match across mammals?

Answer: Homologous structures. Same bone pattern across species indicates common ancestral structure.

Flashcard 44: Which evidence for evolution compares similar features that evolved independently in similar environments?

Answer: Analogous structures (convergent evolution). Similar functions evolved independently due to similar environmental pressures.

Flashcard 45: Which statement best defines evolution at the population level?

Answer: Change in allele frequencies over time. Evolution occurs when allele proportions shift between generations.

Flashcard 46: Calculate $q$ if the recessive phenotype frequency is $q^2 = 0.36$.

Answer: $q = 0.6$. Take the square root of the recessive phenotype frequency.

Flashcard 47: Which type of selection favors intermediate phenotypes and reduces extremes?

Answer: Stabilizing selection. Average trait values are preserved while extremes are eliminated.

Flashcard 48: What is the definition of allele frequency in a population?

Answer: Proportion of all gene copies that are a specific allele. Calculated by dividing copies of one allele by total gene copies in the population.

Flashcard 49: What is a vestigial structure evidence for?

Answer: Descent with modification from ancestors. Reduced or nonfunctional structures inherited from functional ancestors.

Flashcard 50: Find the homozygous recessive genotype frequency if $q = 0.1$.

Answer: $q^2 = 0.01$. Square the recessive allele frequency: $0.1^2$.

Flashcard 51: Which outcome indicates Hardy–Weinberg equilibrium if genotype frequencies match $p^2$, $2pq$, and $q^2$?

Answer: No evidence of evolution for that gene in that population. Matching Hardy-Weinberg expectations indicates no evolutionary forces acting.

Flashcard 52: Calculate $p$ if the recessive phenotype frequency is $q^2 = 0.09$.

Answer: $p = 0.7$. If $q^2 = 0.09$, then $q = 0.3$ and $p = 1 - 0.3 = 0.7$.

Flashcard 53: Which type of selection maintains multiple alleles because heterozygotes have highest fitness?

Answer: Heterozygote advantage (balancing selection). Heterozygotes outperform both homozygotes, preserving both alleles.

Flashcard 54: State the Hardy–Weinberg genotype frequency equation.

Answer: $p^2 + 2pq + q^2 = 1$. Expansion of $(p + q)^2$ gives genotype frequencies for diploid organisms.

Flashcard 55: Which genotype frequency corresponds to homozygous recessive under Hardy–Weinberg?

Answer: $q^2$. Probability of getting recessive allele from both parents equals $q \times q$.

Flashcard 56: What is the Hardy–Weinberg principle used to evaluate in populations?

Answer: Whether a population is evolving (deviating from equilibrium). Compares observed frequencies to equilibrium expectations to detect evolution.

Flashcard 57: Identify the evolutionary mechanism that introduces new alleles by DNA change.

Answer: Mutation. DNA errors during replication create novel alleles in populations.

Flashcard 58: Which genotype frequency corresponds to heterozygotes under Hardy–Weinberg?

Answer: $2pq$. Two ways to get heterozygotes: dominant-recessive or recessive-dominant.

Flashcard 59: Which evidence for evolution is based on similarities in DNA or amino acid sequences?

Answer: Molecular homology. DNA and protein similarities reflect shared evolutionary history.

Flashcard 60: A population has $p = 0.4$; what is the expected homozygous recessive frequency?

Answer: $q^2 = 0.36$. If $p = 0.4$, then $q = 0.6$, so $q^2 = 0.36$.

Flashcard 61: State the Hardy–Weinberg allele frequency equation.

Answer: $p + q = 1$. For a two-allele system, frequencies must sum to one.

Flashcard 62: Which outcome indicates Hardy–Weinberg equilibrium if genotype frequencies match $p^2$, $2pq$, and $q^2$?

Answer: No evidence of evolution for that gene in that population. Matching Hardy-Weinberg expectations indicates no evolutionary forces acting.

Flashcard 63: Which evidence for evolution uses preserved remains and their ages to show change over time?

Answer: Fossil record. Chronological sequence of fossils reveals morphological changes over time.

Flashcard 64: Which mechanism is most consistent with a new allele appearing after replication errors?

Answer: Mutation. DNA replication errors create entirely new genetic variants.

Flashcard 65: Identify the best evidence for recent evolution if pesticide resistance rises in a pest population.

Answer: A measurable increase in resistance allele frequency over generations. Direct measurement of evolutionary change through allele frequency shifts.

Flashcard 66: Which observation best supports gene flow as the cause if two populations become genetically similar?

Answer: Increased migration accompanied by reduced allele frequency differences. Migration homogenizes allele frequencies between previously distinct populations.

Flashcard 67: Which mechanism is most consistent with increased allele mixing after individuals immigrate?

Answer: Gene flow. Immigration introduces new alleles and increases genetic mixing.

Flashcard 68: Which type of selection favors both extremes and can create a bimodal distribution?

Answer: Disruptive selection. Selection against intermediates can lead to population splitting.

Flashcard 69: Which evidence best supports convergent evolution if two unrelated species share similar functions but not ancestry?

Answer: Analogous structures. Similar function without shared ancestry indicates independent evolution.

Flashcard 70: Find the expected heterozygote frequency if $p = 0.5$ and $q = 0.5$.

Answer: $2pq = 0.5$. When allele frequencies are equal, heterozygotes reach maximum frequency.

Flashcard 71: Which term describes a change in allele frequencies in a population across generations?

Answer: Microevolution. Evolution within a population, as opposed to macroevolution between species.

Flashcard 72: Calculate $p$ if the recessive allele frequency is $q = 0.2$.

Answer: $p = 0.8$. Since $p + q = 1$, subtract $q$ from 1.

Flashcard 73: Which evidence for evolution uses preserved remains and their ages to show change over time?

Answer: Fossil record. Chronological sequence of fossils reveals morphological changes over time.