AP BIOLOGY

Detailed explanation-1: -Homologous structures provide evidence for common ancestry, while analogous structures show that similar selective pressures can produce similar adaptations (beneficial features). Similarities and differences among biological molecules (e.g., in the DNA sequence of genes) can be used to determine species’ relatedness.

Detailed explanation-2: -DNA evidence for evolution Biologists often compare the sequences of related (or homologous) genes. If two species have the “same” gene, it is because they inherited it from a common ancestor. In general, the more DNA differences in homologous genes between two species, the more distantly the species are related.

Detailed explanation-3: -Five types of evidence for evolution are discussed in this section: ancient organism remains, fossil layers, similarities among organisms alive today, similarities in DNA, and similarities of embryos.

Detailed explanation-4: -Ancestral organism shared by two or more descendent lineages-in other words, an ancestor that they have in common. For example, the common ancestors of two biological siblings include their parents and grandparents; the common ancestors of a coyote and a wolf include the first canine and the first mammal.