Origin and Evolution of Life: High-Priority Study Guide

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Earth's Formation: The Earth is estimated to be approximately 4.6 billion years old.
Earliest Life: The first evidence of life dates back to about 3.5–3.8 billion years ago, with fossilized stromatolites produced by cyanobacteria.
Miller-Urey Experiment: This classic experiment simulated early Earth conditions and demonstrated that amino acids (the building blocks of proteins) could form abiotically, but did not create life itself.

Prokaryotes: The earliest life forms were prokaryotic cells.
Cyanobacteria: Photosynthetic prokaryotes that contributed to oxygen accumulation in the atmosphere.
Oxygen Accumulation: Led to the evolution of aerobic organisms and the eventual rise of eukaryotes.
Eukaryotes: Cells with membrane-bound organelles appeared after prokaryotes.
Multicellular Organisms: Evolved from single-celled ancestors.
Animals and Colonization of Land: Animals evolved and later colonized terrestrial environments.

Definition: Diagrams that depict evolutionary relationships among organisms.
Key Principle: The most closely related organisms share the most recent common ancestor.

Definition: A structure that originally evolved for one function but was later adapted for a different function.
Example: Feathers in birds may have originally evolved for temperature regulation and were later co-opted for flight.

Bryophytes: Non-vascular plants (e.g., mosses); gametophyte dominant; require water for reproduction.
Seedless Vascular Plants: (e.g., ferns); have vascular tissue; sporophyte dominant.
Gymnosperms: Seed plants with cones; produce seeds and pollen but no fruits.
Angiosperms: Flowering plants; produce flowers, fruits, and enclosed seeds.

Male Structure (Stamen): Consists of the anther (produces pollen) and filament (supports anther).
Female Structure (Carpel/Pistil): Includes stigma (receives pollen), style (pollen tube grows through), and ovary (contains ovules).
Fertilization Process: Pollen lands on stigma, sperm travels through style, ovules become seeds, and ovary develops into fruit.

Xylem: Transports water and minerals from roots to shoots.
Phloem: Transports sugars from sources (e.g., leaves) to sinks (e.g., roots, fruits).
Guard Cells: Regulate the opening and closing of stomata for gas exchange and water loss.
Root Hairs: Increase surface area for water and mineral absorption.
Apical Meristems: Regions of active cell division responsible for primary growth (lengthening of roots and shoots).
Parenchyma: General plant cells that are totipotent (can differentiate into other cell types).
Transpiration: The process of water loss from leaves, driving the upward movement of water through xylem.

Sponges: Lack true tissues; simple body plan.
Cnidarians: Exhibit radial symmetry; possess cnidocytes (stinging cells); have a gastrovascular cavity.
Flatworms (Platyhelminthes): Bilateral symmetry; gastrovascular cavity.
Three Worm Phyla: Platyhelminthes (flatworms), Nematoda (roundworms), Annelida (segmented worms).
Arthropods: Characterized by an exoskeleton, segmented body, and jointed appendages.
Echinoderms: Possess a water vascular system and tube feet (e.g., starfish).
Chordates: Defined by notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail.

Lichens: Symbiotic association between a fungus and an alga or cyanobacterium.
Mycorrhizae: Mutualistic relationship between fungi and plant roots; fungus provides water and minerals, plant provides sugars.

Archaea: Prokaryotes adapted to extreme environments.
Dinoflagellates: Belong to the SAR (Stramenopiles, Alveolates, Rhizarians) supergroup.
Plant Evolution: Plants evolved from green algae.
Opisthokonta: Animals and fungi are part of this eukaryotic supergroup.
Carboniferous Period: Characterized by extensive coal forests and the first appearance of seed plants.