AP BIOLOGY

Detailed explanation-1: -If two or more species share a unique physical feature, such as a complex bone structure or a body plan, they may all have inherited this feature from a common ancestor. Physical features shared due to evolutionary history (a common ancestor) are said to be homologous.

Detailed explanation-2: -Similarities in embryos are likely to be evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails. All of the embryos in Figure 9.3. 4, except for fish, lose their gill slits by adulthood, and some of them also lose their tail.

Detailed explanation-3: -Similarities in embryos are evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails (see the Figure below). Most vertebrates, except for fish, lose their gill slits by adulthood.

Detailed explanation-4: -Anatomical similarities between organisms support the idea that these organisms evolved from a common ancestor. Thus, the fact that all vertebrates have four limbs and gill pouches at some part of their development indicates that evolutionary changes have occurred over time resulting in the diversity we have today.

Detailed explanation-5: -Anatomy. Species may share similar physical features because the feature was present in a common ancestor (homologous structures). Molecular biology. DNA and the genetic code reflect the shared ancestry of life.