Study Guide for Georgia Milestones Biology EOC
Overview and Domains of Assessment
Biology EOC Assessment Structure: The Georgia Milestones Biology End of Course (EOC) assessment organizes standards into five primary domains: * Cells * Classification & Phylogeny * Theory of Evolution * Cellular Genetics & Heredity * Ecology
Hierarchical Organization: Life is organized across every level, ranging from the individual cell up to the global biosphere.
Key Areas of Focus (Georgia Performance Standards): * SB1a: Interaction of organelles and structures within a cell to maintain homeostasis. * SB1c: Relationship between macromolecule structures and cellular processes. * SB4a: Construction of clades within the three domains (Archaea, Bacteria, and Eukarya) based on patterns of structure and function. * SB4b: Use of cladograms and phylogenetic trees as models of common ancestry and evolutionary relationships. * SB4c: Comparison of viruses and living organisms. * SB6a: Influence of the age of Earth, speciation, and genetics on the transition from preexisting species to new species. * SB6b: Speciation and its role in creating patterns of biodiversity. * SB6c: Evidence for common descent through comparative morphology, embryology, biochemistry, and genetics. * SB6d: Role of undirected genetic changes (natural selection and genetic drift) in population changes. * SB6e: The role of evolution in biological resistance.
Organizational and Cellular Foundations
The Shift in Biological Focus: Historically, biologists studied macro-structures like organs, tissues, and cell cultures. The invention and advancement of the microscope shifted focus to smaller cellular elements known as organelles.
Prokaryotic vs. Eukaryotic Categories: Microscopic advancements led to the discovery of two distinct cell types: prokaryotic and eukaryotic.
Cell Boundaries and Membranes: * Cell Membrane: Every cell possesses a cell membrane acting as a boundary with the external environment. Characteristics include: * Flexibility: Allows the cell to vary its shape. * Regulation: Controls the movement of materials entering and exiting the cell. * Homeostasis: Maintains chemical balance within the cell. * Cell Wall: An additional, outer boundary found in specific organisms. * Characteristics: Thicker than the membrane and inflexible; provides protection and structural shape. * Occurrence: Found in plants, fungi, most bacteria, and a few protists. * Absence: Animal cells do not possess cell walls.
Classification and the Three-Domain System
Evolution of Classification Systems: * Aristotelian Period: Early systems were based solely on visible structural differences and did not account for geological time frames. * Modern Shift: Classification now relies on evolutionary relationships, DNA sequences, and protein similarities.
The Three Domains: * Domain Bacteria: Contains all prokaryotic organisms that are either pathogenic (disease-causing) or beneficial. * Domain Archaea: Contains prokaryotic organisms primarily found in extreme environments, including hot springs, swamps, and the deep ocean. * Domain Eukarya: Contains all organisms with membrane-bound organelles.
Categories Within Eukarya: * Protists: Unicellular or multicellular organisms lacking complex organ systems, typically living in moist environments. Genome analysis continues to shift their specific placements within the domain. * Fungi: Unicellular or multicellular heterotrophic eukaryotes. They are non-motile consumers that absorb nutrients from wastes and decomposing organisms. * Plants: Multicellular, photosynthetic eukaryotes. Most feature cellulose cell walls and tissues organized into organs and organ systems. * Animals: Multicellular eukaryotic consumers. They lack cell walls and possess complex organ systems, such as the nervous, muscular, and digestive systems.
Taxonomy and the Modern Classification System
Definition: Taxonomy is the biological branch dedicated to naming and grouping organisms.
Taxonomist Methodology: Scientists identify new species by: * Comparing internal and external structures. * Sequencing genomes. * Comparing amino acid sequences of common proteins. * Analyzing evolutionary relationships.
Discovery Rates: The identification of species is increasing due to microscopic technology and the exploration of new frontiers, such as deep ocean areas and tropical forest canopies.
Classification Levels: Modern classification utilizes a hierarchical structure involving seven levels: 1. Domain (overarching level replacing the older kingdom system). 2. Phylum (subdivided by evolutionary traits). 3. Class (based on shared characteristics). 4. Order (based on more specific/limited characteristics). 5. Family. 6. Genus. 7. Species.
Defining a Species: The most specific level; members are the same "kind" and can reproduce to create viable offspring.
Note on Older Systems: While the six-kingdom system has been largely superseded by the three-domain system, it remains a useful tool for identification.
Comparative Analysis of Viruses and Living Organisms
Viral Structure: * Capsid: A protein shell containing genetic material. * Genetic Material: Can be DNA or RNA, and single-stranded or double-stranded. * Membranous Envelope: Found in some viruses; derived from the host cell membrane and contains viral and host lipids/proteins.
Living vs. Non-Living Comparison: * Similarities: Viruses contain genetic material, evolve over time, and respond to their environments. * Differences: Viruses are not cells, lack organelles, and cannot reproduce outside of a living host cell. * Crystallization: Viruses can form crystals and maintain functionality; living cells cannot survive the crystallization process.
Evolutionary Theory and Biodiversity
Foundations: The work of Charles Darwin and Gregor Mendel provides the basis for understanding modern species diversity.
Darwin’s Finches: On the Galápagos Islands, Darwin observed over a dozen finch species believed to have evolved from a single founding species through adaptation to new environments.
Biodiversity Defined: The variety of organisms, their genetic information, and the communities where they reside.
Speciation: The evolution of new species resulting from changes in gene flow between populations of ancestral species. * Geographic Isolation: Physical barriers such as volcanoes, earthquakes, and sea-level changes separate populations. * Process: Separated populations adapt via natural selection until gene pools become so distinct that a new species is formed.
Molecular Evidence: High levels of similarity in DNA and protein amino acid sequences across all living organisms indicate that life diversified by altering the genetic code of a common ancestor.
Fossil Evidence and Geochronology
The Fossil Record: Provides an incomplete picture because fossils usually consist of hard parts (bones, shells, or thick-walled plants). * Rarity: Details of internal organs or skin are rarely preserved. * Intermediate Forms: Missing transition species are rare because approximately of all historical organisms were soft-bodied and did not fossilize. * Destruction: Fossils are often lost to wind, rain, soil erosion, or pressure from overlying rocks.
Dating Methods: * Relative Dating: Paleontologists determine the age of fossils by matching them with specific rock layers. * Radioisotope Dating: Uses isotopes as "clocks" to measure absolute time.
Isotopes in Geochronology: * Carbon-14 (C-14): Primary isotope for organic remains. Once an organism dies, it stops taking in carbon. Scientists measure the ratio of C-14 to its stable form. * Half-life: The half-life of C-14 is years. * Decay: Half of the C-14 becomes stable N-14 over one half-life. * Limit: After approximately years, traceable carbon levels are usually gone. * Uranium-235: Used for older samples; decays into lead-207 (Pb-207) over approximately million years.
Phylogeny: A description of lines of descent. * Phylogenetic Trees: Models showing interrelationships among species. * Inference: When fossil records are incomplete, biologists infer phylogenies by comparing DNA sequences, chromosomal characteristics, and morphological features.