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AP Intermediate Zoology (BIEAP) study materials
AP Intermediate Zoology (BIEAP) study resources

AP Intermediate Zoology (BIEAP): Animal Diversity and Classification

AP Intermediate Zoology (BIEAP) · Work through your exam, one topic at a time.

All guide sections

Animal Diversity and Classification

This domain tests how the animal kingdom is organised and how binomial nomenclature is applied. BIEAP questions typically ask you to place an organism in the correct phylum using body-plan characters, or to interpret a scientific name and its hierarchy.

Classification framework

  • Taxonomic hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species. A species name is binomial: genus capitalised, species lowercase, both italicised (Panthera leo).
  • Body-plan criteria: level of organisation (cellular, tissue, organ), symmetry (asymmetrical, radial, bilateral), germ layers (diploblastic, triploblastic), coelom (acoelomate, pseudocoelomate, coelomate), segmentation and cephalisation.
  • Major invertebrate phyla: Porifera (sponges, cellular level, ostia, spongocoel); Cnidaria (cnidocytes, radial, diploblastic, gastrovascular cavity); Platyhelminthes (flatworms, acoelomate); Nematoda (pseudocoelomate, cuticle); Annelida (segmented coelomates, nephridia); Arthropoda (jointed appendages, chitin exoskeleton, largest phylum); Mollusca (mantle, radula, reduced coelom); Echinodermata (water-vascular system, deuterostomes); Hemichordata.
  • Chordata: notochord, dorsal hollow nerve cord, pharyngeal gill slits, post-anal tail. Subphyla Urochordata, Cephalochordata, Vertebrata.

Worked example

An animal is bilaterally symmetrical, triploblastic, has a true coelom, closed circulatory system and metameric segmentation with nephridia. Reasoning: bilateral symmetry plus triploblastic organisation and a coelom excludes Cnidaria and Platyhelminthes; segmentation with nephridia and closed circulation points to Annelida. If it also had jointed appendages and a chitinous exoskeleton, the same body plan would lead to Arthropoda, not Annelida.

Traps

Echinoderm adults are radially symmetrical but are triploblastic deuterostomes; their larvae are bilateral. Pseudocoelomates such as Nematoda are not coelomates. A notochord is not the same as a nerve cord. Molluscan coelom is reduced. Do not use common names alone in answers.