Unit 5 Classification and Evolution Notes

• Classification: The process of grouping organisms based on shared characteristics and evolutionary history.

• Taxonomy: The science of naming and classifying organisms into hierarchical categories, such as domain, kingdom, phylum, class, order, family, genus, and species.

• Evolution: The change in the heritable characteristics of biological populations over successive generations, driven by mechanisms such as natural selection, mutation, gene flow, and genetic drift.

Domains and Kingdoms of Taxonomy

1. Domains

• Bacteria: Unicellular prokaryotes with cell walls containing peptidoglycan. Examples include E. coli and Streptococcus.

• Archaea: Unicellular prokaryotes that often live in extreme environments. Cell walls do not contain peptidoglycan. Examples include Thermoplasma and Halobacterium.

• Eukarya: Multicellular or unicellular organisms with complex cells containing a nucleus. This domain encompasses a variety of organisms, including:

  • Plantae: Kingdom of photosynthetic organisms like trees and flowers.

  • Animalia: Kingdom that includes all animals, such as mammals and birds.

  • Fungi: Kingdom of organisms like mushrooms and yeast, which absorb nutrients.

  • Protista: A diverse group that includes organisms like algae and protozoa, often unicellular.

2. Kingdoms

• Plantae

  • Characteristics: Multicellular, photosynthetic eukaryotes.

  • Example: Flowering plants like roses and grasses.

• Animalia

  • Characteristics: Multicellular, heterotrophic eukaryotes that usually have complex organ systems.

  • Example: Mammals like humans and birds like eagles.

• Fungi

  • Characteristics: Multicellular (mostly), eukaryotic organisms that decompose organic matter.

  • Example: Yeasts and molds, such as Penicillium.

• Protista

  • Characteristics: Mostly unicellular eukaryotic organisms that do not fit in other kingdoms.

  • Example: Amoeba, Paramecium, and algae such as Chlamydomonas.