CLEP Biology Mechanisms of Natural Selection 4 — Questions and Answers
Question 1: Convergent evolution is best demonstrated by which example?
- The wings of bats and birds (Correct answer)
- The forelimbs of humans and whales
- Similar DNA sequences in chimps and humans
- The embryonic gill slits in vertebrates
Correct answer: The wings of bats and birds
Bat and bird wings evolved flight independently in separate lineages, representing convergent evolution of analogous structures.
Question 2: Which statement about mutations and natural selection is most accurate?
- Mutations occur in response to environmental needs
- Natural selection creates new mutations to improve fitness
- Mutations are random; selection acts on the variation they create (Correct answer)
- Only beneficial mutations can be passed to offspring
Correct answer: Mutations are random; selection acts on the variation they create
Mutations arise randomly and independently of need; natural selection then acts on the phenotypic variation they generate.
Question 3: If a population of rabbits shows p = 0.7 (frequency of allele A) and q = 0.3 (frequency of allele a), what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?
- 0.09
- 0.42 (Correct answer)
- 0.49
- 0.21
Correct answer: 0.42
Heterozygote frequency = 2pq = 2(0.7)(0.3) = 0.42 under Hardy-Weinberg equilibrium.
Question 4: An organism that produces many offspring but provides no parental care is exhibiting which life history strategy?
- K-selection
- r-selection (Correct answer)
- Stabilizing selection
- Kin selection
Correct answer: r-selection
r-selected species maximize reproduction by producing many offspring with little investment in each individual offspring.
Question 5: Kin selection explains altruistic behavior because:
- Relatives always cooperate to avoid predation
- Helping relatives can increase the spread of shared genes (inclusive fitness) (Correct answer)
- Altruism reduces competition within a population
- Natural selection rewards social behavior in all species
Correct answer: Helping relatives can increase the spread of shared genes (inclusive fitness)
Kin selection favors altruism when the benefit to relatives (weighted by relatedness) exceeds the cost to the altruist, increasing inclusive fitness.
Question 6: What is the primary reason that sexual reproduction accelerates evolution compared to asexual reproduction?
- It increases the mutation rate
- It generates new combinations of alleles through recombination and meiosis (Correct answer)
- It doubles the number of offspring per generation
- It allows organisms to select advantageous mutations
Correct answer: It generates new combinations of alleles through recombination and meiosis
Meiosis and recombination in sexual reproduction shuffle alleles into new combinations, greatly increasing the genetic variation on which selection can act.
Question 7: Which mechanism of speciation occurs when a geographic barrier divides a population?
- Sympatric speciation
- Parapatric speciation
- Allopatric speciation (Correct answer)
- Peripatric speciation
Correct answer: Allopatric speciation
Allopatric speciation occurs when a physical barrier (e.g., mountain range, ocean) geographically isolates populations, preventing gene flow.
CLEP Biology Mechanisms of Natural Selection 4
Convergent evolution is best demonstrated by which example?