Evidence used in Classification

• What were early classification systems based on?

  Appearance
• What problem arises when classifying animals based solely on appearance?

  Two animals may look very similar but belong to different families, genus, and species.
• Why is cytochrome C considered a useful molecule in classification?

  It varies between species and is a protein used in respiration, required by all organisms.
• What other protein could be used in classification besides cytochrome C?

  Hemoglobin
• What other biological molecules can be compared for classification purposes?

  RNA and DNA
• How do large biochemical molecules provide evidence of evolution?

  Similarities in these molecules imply evolutionary relationships, while differences indicate evolutionary distance.
• What does a similar sequence of RNA or DNA suggest about species?

  A similar sequence implies a closer evolutionary relationship.