2026 End of Year Science Vocabulary Competition Practice Test

Evolution explains how allele frequencies in a population shift over generations, so certain heritable traits become more common. When traits confer a survival or reproductive advantage, individuals with those traits leave more offspring, passing on the associated alleles more often. Over many generations, this differential success changes the population’s trait distribution. Natural selection is a primary mechanism that drives this change, favoring advantageous traits, while mutation introduces new variation and genetic drift can alter frequencies randomly. So, the broader process is evolution, with natural selection often playing the leading role in increasing the prevalence of beneficial traits.