AP BIOLOGY

Detailed explanation-1: -Previous comparative DNA sequence studies have revealed that genes similar to each other at the nucleotide level can be related to one another by different evolutionary histories.

Detailed explanation-2: -Molecular clocks are used to determine how closely two species are related by calculating the number of differences between the species’ DNA sequences or amino acid sequences. These clocks are sometimes called gene clocks or evolutionary clocks.

Detailed explanation-3: -Molecular biology. Similarities and differences between the “same” gene in different organisms (that is, a pair of homologous genes) can help us determine how closely related the organisms are.

Detailed explanation-4: -By comparing the sequences of genomes of different organisms, researchers can understand what, at the molecular level, distinguishes different life forms from each other.

Detailed explanation-5: -Organisms that share similar physical features and genetic sequences tend to be more closely related than those that do not. Features that overlap both morphologically and genetically are referred to as homologous structures; the similarities stem from common evolutionary paths.