Unit 10: Part 2 Notes/Study Guide

Node

Represents the most recent common ancestor of the two species or groups that branch from it.

Common Ancestor

Represented by a node on a phylogenetic tree, it is where organisms branching from that node share evolutionary history.

Clade

Includes a common ancestor and all of its descendants.

Biogeography

The study of where species live now and where their ancestors lived; shows evolution through species adaptation to different environments.

Fossils

Preserved remains or traces of ancient organisms; help show changes over time and transitional forms.

Homologous Structures

Body parts that are similar in structure but may have different functions, suggesting common ancestry.

Analogous Structures

Body parts that have similar functions but different structures; a result of convergent evolution.

Vestigial Structures

Structures that have lost their original function, suggesting descent from ancestors where the structure was useful.

Molecular Biology

The study of DNA, RNA, and proteins; more similar DNA indicates closer evolutionary relationships.

Relative Dating

Determining the age of fossils or rocks by comparing their placement in layers; does not provide exact ages.

Radiometric Dating

Using the decay of radioactive isotopes to calculate absolute age; provides actual numerical ages.