Classification of Living Organisms & Kingdoms

All living organisms share fundamental biological life processes, summarized by the mnemonic **MR NIGER D**: • Movement: The ability of an organism to change the position or posture of its entire body (locomotion in animals) or parts of its body (tropisms in plants bending towards sunlight). • Respiration: The biochemical oxidation of glucose inside living cells to release usable metabolic energy (ATP). • Nutrition: The process of obtaining or synthesizing nutrients required for growth, tissue repair, and energy (autotrophic in green plants; heterotrophic in animals and fungi). • Irritability (Sensitivity): The capacity to detect changes in the external or internal environment (stimuli) and respond appropriately (e.g. eyes responding to light, mimosa leaves folding on touch). • Growth: A permanent, irreversible increase in the size, dry mass, and complexity of an organism. • Excretion: The removal of toxic metabolic waste products of chemical reactions from the body (e.g. carbon dioxide, urea, excess water). [Note: Egestion is not excretion!]. • Reproduction: The ability of mature organisms to produce offspring of their own kind to ensure the survival and continuity of the species. • Death: The irreversible cessation of all biological and metabolic processes.

• What is Classification? Biological classification (Taxonomy) is the scientific grouping of living organisms based on their shared evolutionary, anatomical, and genetic characteristics. • Importance of Classification: 1. Brings order and clarity to the study of over 1.7 million cataloged species. 2. Enables easy identification of newly discovered organisms. 3. Facilitates universal scientific communication across different languages. 4. Reveals evolutionary relationships among diverse organisms. • The Linnaean Taxonomic Hierarchy (From broadest to most specific): Kingdom → Phylum (or Division in plants) → Class → Order → Family → Genus → Species - Mnemonic: "King Philip Came Over For Good Soup". - Species: The basic unit of classification. A group of closely related organisms capable of interbreeding in nature to produce fertile offspring. • Binomial Nomenclature: Devised by Carl Linnaeus; every organism is given a two-part Latinized scientific name: - First name: Genus (capitalized). - Second name: species (lowercase). - Must be italicized in print or underlined separately when handwritten (e.g. *Homo sapiens* for Humans; *Zea mays* for Maize; *Mangifera indica* for Mango).

Biologists classify all life into Five Major Kingdoms: 1. Kingdom Monera (Prokaryotes): - Microscopic, single-celled organisms that LACK a true membrane-bound nucleus and organelles (prokaryotic cells). Genetic material floats freely in cytoplasm. - Examples: Bacteria (e.g. *Escherichia coli*, *Lactobacillus*), Blue-green algae (Cyanobacteria). 2. Kingdom Protista (Protoctista): - Mostly single-celled microscopic organisms that POSSESS a true membrane-bound nucleus (eukaryotic cells). - Some are animal-like (Protozoa: *Amoeba*, *Paramecium*, *Plasmodium*); some are plant-like algae (*Spirogyra*, *Chlamydomonas*, *Euglena*). 3. Kingdom Fungi: - Non-green eukaryotic organisms that lack chlorophyll and cannot perform photosynthesis. - Cell walls are made of CHITIN (not cellulose). - Nutrition: Heterotrophic saprophytes (secrete enzymes externally onto decaying matter and absorb digested nutrients). - Examples: Mushrooms, Yeast, Bread mold (*Rhizopus*), Toadstools. 4. Kingdom Plantae: - Multicellular eukaryotic autotrophs with cellulose cell walls containing chlorophyll to manufacture food by photosynthesis. - Examples: Mosses, Ferns, Conifers, Flowering plants (Maize, Mango, Cocoa, Baobab). 5. Kingdom Animalia: - Multicellular eukaryotic heterotrophs without cell walls, with nervous coordination and capable of active locomotion. - Examples: Insects, Tilapia, Frogs, Lizards, Eagles, Lions, Humans.