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Science Unit 1: Evolution
Grade 8 evolution: two forms of evidence and how evolution happens. Bonus is the older-grades add-on (third evidence form, Mendel/Punnett, speciation, trees).
25 terms (15 core · 10 bonus) · Grade 8
Self-check quiz
Term list
Section 1 (15)
- Homologous structures — Body parts with the same underlying structure but different jobs, inherited from a shared ancestor.
- Embryological homology — Early embryos of related species look alike, which points to a shared ancestor.
- Molecular homology — Similar DNA or proteins mean species share a closer common ancestor.
- Anatomical homology — Body parts that have the same bone layout because they come from a shared ancestor.
- Vestigial structures — A leftover body part that no longer does its old job.
- Analogous structures — Parts with the same job but a different structure, not from a recent common ancestor (convergent evolution).
- Biological traits — Inherited features of an organism, in its body or behavior, that can be passed on.
- Population vs individual — Evolution happens to a population over generations, not to one animal in its lifetime.
- Natural selection — Traits that help survival and reproduction become more common in a population.
- Gene flow — Genes move when individuals migrate and breed with another population.
- Genetic drift — Chance events change allele frequencies, and the effect is strongest in small populations.
- Mutation — A change in DNA that can create a new allele.
- Microevolution — Small changes in allele frequencies inside a population.
- Macroevolution — Big changes above the species level over a long time, such as new groups of organisms.
- Speciation — One species splits into two that can no longer interbreed.
Bonus (10)
- Mendelian genetics — Traits are passed by pairs of alleles, one from each parent (dominant and recessive).
- Phenotype — The trait you can see or observe.
- Genotype — The allele pair, often written as letters.
- Phenotype ratio — How often each visible trait shows up among offspring.
- Genotype ratio — How often each allele pair shows up among offspring.
- Punnett square — A grid that predicts the allele combinations offspring can get.
- Monohybrid cross — A cross that tracks one trait.
- Phylogenetic tree — A diagram of how species are related through common ancestors.
- Convergent evolution — Unrelated species evolve similar traits because they face similar pressures.
- Common ancestor — An earlier species that two or more later species both came from.