Classification of Living Things

Classification in Living Things

• Classification involves organizing living organisms into hierarchical categories: Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Taxonomy is the scientific study of classification systems for living things.

Nomenclature

• Binomial nomenclature assigns a two-word scientific name to each organism, featuring the genus first followed by the species.

Taxonomic Hierarchy

• Kingdom: The largest taxonomic grouping, consisting of closely related phyla.
• Phylum: Major classification category below a kingdom, encompassing animals and plants.
• Class: Group of similar orders within a phylum.
• Order: Classification grouping closely related families.
• Family: Taxonomic group that includes one or more genera.
• Genus: Category of closely related species, forms the first part of a scientific name.
• Species: Group of similar organisms capable of breeding and producing fertile offspring.

Cell Types

• Prokaryotic cells lack a nucleus and membrane-bound organelles, known primarily as bacteria.
• Eukaryotic cells contain a nucleus and other membrane-bound organelles.

Six Kingdoms of Life

• Includes archaebacteria, eubacteria, protists, fungi, plants, and animals.

Groups within Kingdoms

• Archaebacteria: Unicellular prokaryotes with no peptidoglycan in cell walls.
• Eubacteria: Unicellular prokaryotes with peptidoglycan in cell walls.
• Protists: Mostly unicellular eukaryotic organisms, distinct from other kingdoms.
• Fungi: Heterotrophic organisms that acquire nutrients from decomposing organic matter.
• Plants: Multicellular eukaryotes that primarily produce food via photosynthesis.
• Animals: Multicellular, heterotrophic eukaryotes that reproduce sexually and have mobility.

Taxonomy Tools

• Taxonomy key: Method using paired statements to describe organism characteristics.

Nutritional Classification

• Heterotrophs cannot produce their own food, relying on other organisms.
• Autotrophs create their own food, usually through photosynthesis.

Specific Organisms

• Amoeba: A one-celled organism that changes shape for locomotion.
• Paramecium: A ciliated protist, feeds through openings in its membrane.
• Hydra: Belongs to the Phylum Cnidaria.
• Earthworm: Classified under the Phylum Annelida.
• Grasshopper: Falls under the Phylum Arthropoda.
• Humans: Classified in the Phylum Chordata.

Evolutionary Theory

• Darwin's theory emphasizes variation within species, the struggle for existence, survival of the fittest, and the gradual evolution of species over time.