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Living Things Classification

Jun 8, 2025

Overview

This lecture covers the classification of living things, explaining why classification is important, the main groups (kingdoms), and the characteristics used to differentiate living organisms.

Introduction to Classification

  • Classification is the organization of living things into groups based on similarities and differences.
  • Scientists classify to better understand relationships, study diversity, and simplify identification.

Major Groups of Living Things (Kingdoms)

  • Living things are classified into major groups called kingdoms.
  • The traditional five kingdoms are: Animalia, Plantae, Fungi, Protista, and Monera (Bacteria).
  • Each kingdom has unique features distinguishing its members.

Criteria for Classification

  • Organisms are classified based on shared characteristics such as cell type, number of cells, and how they obtain food.
  • Examples of classification criteria include prokaryotic vs. eukaryotic cells, and autotroph (make their own food) vs. heterotroph (consume other organisms).

Key Features of Each Kingdom

  • Animals: Multicellular, eukaryotic, no cell walls, heterotrophs.
  • Plants: Multicellular, eukaryotic, have cell walls, autotrophs (photosynthesis).
  • Fungi: Mostly multicellular, eukaryotic, cell walls, heterotrophs (decomposers).
  • Protists: Mostly unicellular, eukaryotic, diverse methods of getting food.
  • Monera (Bacteria): Unicellular, prokaryotic, can be autotrophic or heterotrophic.

Importance of Classification

  • Allows scientists to identify, name, and study organisms more efficiently.
  • Reveals evolutionary relationships between different organisms.

Key Terms & Definitions

  • Classification — Grouping living things based on similarities for easier study and identification.
  • Kingdom — One of the largest groups used to classify living things.
  • Autotroph — Organism that produces its own food (usually by photosynthesis).
  • Heterotroph — Organism that obtains food by consuming other organisms.
  • Prokaryotic — Cells without a defined nucleus (e.g., bacteria).
  • Eukaryotic — Cells with a defined nucleus (e.g., animals, plants, fungi, protists).

Action Items / Next Steps

  • Review examples of organisms in each kingdom.
  • Prepare notes on the distinguishing characteristics of each kingdom.
  • Read textbook section on cellular structure differences in kingdoms.