Theories

"SPONTANEOUS GENERATION" -or- "ABIOGENESIS"
--- living things arising from nonliving things
--- abolised in 1660 by Francesco Redi

"BIOGENESIS"
--- living things arising from pre-existing living things
--- term coined in 1870 by Thomas Henry Huxley

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Chemical Basis of Life

"ATOM" indivisible particle (parts: nucleus, protons, neutrons, electrons) (Et. Greek 'atomos' indivisible)

"ELEMENT" substance made up of only one kind of atoma

"COMPOUND" substance made up of two or more different elements

"MOLECULE" smallest particle of a compound

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Hierchical Organization / Structural Levels

• sub-atomic particles: protons, neutrons, electrons
• atom: indivisible particle (parts: nucleus, protons, neutrons, electrons) (Et. Greek 'atomos' indivisible)
• molecule: smallest particle of a compound
• organelle: membrane-bound compartments within cell
• cell: basic unit of life
• tissue: group of same kind of cells
• organ: group of tissues acting together to perform specific functions
• organ system: group of organs interacting as structural units with integrated functions
• multicellular organism: living entity
• population: localized group of organisms of the same species
• community: group of interacting populations
• ecosystem: system of interdependent communities and environment
• biospehere: world of life