7/29/2019 Blueprint of Life Pracs

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Biology Practicals

Blueprint of Life

Perform a firsthand investigation or gather information from secondary sources (including photographs/

diagrams/models) to observe, analyse and compare the structure of a range of vertebrate forelimbs

Comparative anatomy

Structures in common are evidence of similar inherited characteristics from common ancestors

Structural homology (similar structure). Example: the pentadactyl limb

Most land vertebrates show same pentadactyl (five-digits) limb pattern in arm and leg bones Mammalian forelimbs are said to be homologous structures In bats, the limb is modified to form a wing with the fingers extended and skin stretched between each

finger. Whales have within their single paddle-like fin a fully formed pentadactyl limb.

Inherited this from aquatic ancestors, the lobe-finned fishShows that natural selection has kept the gene for this trait and differences are suited to the environment of the

organism.

http://upload.wikimedia.org/wikipedia/commons/5/5b/Evolution_pl.png