Evolution and Natural Selection Quiz

Grade 12 · Science · Quiz

Test your understanding of evolutionary mechanisms, evidence, and population genetics.

Questions

Which type of selection favors individuals at both extremes of a trait, eliminating the average?
1. Directional selection
2. Stabilizing selection
3. Disruptive selection
4. Sexual selection
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Answer: Disruptive selection
Disruptive (diversifying) selection favors extreme phenotypes over the average, potentially splitting a population into two groups and sometimes leading to speciation.
Convergent evolution produces homologous structures in unrelated species.
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Answer: False
Convergent evolution produces ANALOGOUS structures — similar in function but evolved independently in unrelated species (e.g., wings of bats and insects). Homologous structures come from common ancestry.
The ___ effect is a type of genetic drift where a small group founds a new population.
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Answer: founder
The founder effect occurs when a small group from a larger population establishes a new colony. The founders carry only a subset of the original genetic variation, often leading to distinct allele frequencies.
Which observation was most important to Darwin's development of natural selection?
1. Mendel's pea experiments
2. Variation among Galapagos finches
3. Watson and Crick's DNA structure
4. Pasteur's germ theory
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Answer: Variation among Galapagos finches
Darwin observed that finch species on different Galapagos islands had beaks adapted to different food sources, suggesting they had diverged from a common ancestor — key evidence for natural selection.
Mutations are always harmful to an organism.
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Answer: False
Most mutations are neutral (no effect on fitness), some are harmful, and a few are beneficial. Beneficial mutations can spread through populations via natural selection.
What maintains the Hardy-Weinberg equilibrium in a population?
1. Strong directional selection
2. Small population size
3. No mutation, selection, drift, or gene flow
4. High mutation rate
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Answer: No mutation, selection, drift, or gene flow
Hardy-Weinberg requires: large population, random mating, no mutation, no natural selection, and no gene flow. Violating any condition means the population is evolving.
Structures that perform similar functions in unrelated species but evolved separately are called ___ structures.
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Answer: analogous
Analogous structures look/function similarly but evolved independently in unrelated lineages (convergent evolution). Examples: wings of birds and insects, eyes of vertebrates and cephalopods.
Gene flow between two populations tends to increase genetic differences between them.
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Answer: False
Gene flow REDUCES genetic differences between populations by introducing alleles from one population into another, tending to homogenize the two populations over time.
Which type of evidence for evolution involves comparing DNA sequences across species?
1. Fossil record
2. Comparative anatomy
3. Molecular biology
4. Biogeography
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Answer: Molecular biology
Comparing DNA, RNA, and protein sequences across species reveals evolutionary relationships. More closely related species have more similar sequences — e.g., humans and chimps share ~98.7% DNA identity.
Stabilizing selection in human birth weight favors:
1. Very large babies
2. Very small babies
3. Average-sized babies
4. All sizes equally
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Answer: Average-sized babies
Stabilizing selection reduces variation by favoring the intermediate phenotype. In human birth weight, very large or very small babies have higher mortality, so average-sized babies survive at higher rates.

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