General Biology Exam 1 Study Guide: Concepts in Evolution, Genetics, and Diversity

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Characteristics of Living Things: All living organisms share certain features, such as cellular organization, metabolism, growth, response to stimuli, reproduction, and adaptation.
Levels of Biological Organization: Life is organized from molecules to biosphere, including cells, tissues, organs, organisms, populations, communities, ecosystems, and the biosphere.
Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes possess both.
Producers (autotrophs) vs. Consumers (heterotrophs): Producers make their own food (e.g., plants via photosynthesis); consumers obtain energy by eating other organisms.
Positive/Negative Feedback Systems: Regulatory mechanisms that maintain homeostasis. Negative feedback reduces change; positive feedback amplifies it.
Evolutionary Theory: The scientific model explaining how species change over time through mechanisms such as natural selection.

Prokaryotic vs. Eukaryotic Cells: Prokaryotes (bacteria, archaea) are simpler, lacking a nucleus; eukaryotes (plants, animals, fungi, protists) have complex internal structures.
Endosymbiotic Theory: Explains the origin of mitochondria and chloroplasts in eukaryotic cells as formerly free-living prokaryotes engulfed by ancestral eukaryotes.
Key Differences: Eukaryotes have membrane-bound organelles; prokaryotes do not.
Examples: Bacteria (prokaryote), yeast (eukaryote).

Mitosis: Cell division resulting in two genetically identical diploid cells. Used for growth and repair.
Meiosis: Cell division producing four genetically unique haploid gametes. Essential for sexual reproduction.
Ploidy Levels: Diploid (2n): two sets of chromosomes; haploid (n): one set.
Comparison Table:

Process	Number of Divisions	Resulting Cells	Genetic Identity	Ploidy
Mitosis	1	2	Identical	Diploid
Meiosis	2	4	Unique	Haploid

(mitosis) (meiosis)

Role in Diversity: Meiosis increases genetic diversity via crossing over and independent assortment.

Alleles: Different forms of a gene found at the same locus.
Origin of New Alleles: Mutation is the primary source of new alleles in a population.
Hardy-Weinberg Equilibrium: Mathematical model describing allele and genotype frequencies in a non-evolving population.
Equation:

Genetic Drift, Bottleneck Effect, Founder Effect: Mechanisms that alter allele frequencies in populations, often by chance.
Selection: Natural, sexual, and balancing selection are mechanisms that drive evolution.
Heterozygote Advantage: Heterozygotes may have higher fitness than either homozygote (e.g., sickle cell trait).

Linnaean Classification: Hierarchical system (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species).
Binomial Nomenclature: Two-part scientific naming system (Genus species).
Phylogenetic Trees: Diagrams showing evolutionary relationships; constructed using morphological and molecular data.
Monophyletic, Paraphyletic, Polyphyletic Groups: Types of clades based on shared ancestry.
Horizontal Gene Transfer: Movement of genes between organisms other than by descent.

Darwin and Wallace: Both contributed to the theory of evolution by natural selection.
Major Influences: Geology, populations, and observations from the HMS Beagle.
Natural Selection: Mechanism by which organisms better adapted to their environment tend to survive and reproduce.
Homologous vs. Analogous Structures: Homologous structures share ancestry; analogous structures have similar function but different ancestry.
Evidence for Evolution: Fossil record, comparative anatomy, molecular biology, biogeography.

Origin of New Alleles: Mutation introduces new genetic variation.
Gene Flow: Movement of alleles between populations.
Genetic Drift: Random changes in allele frequencies, especially in small populations.
Bottleneck and Founder Effects: Events that drastically reduce population size and genetic diversity.
Hardy-Weinberg Equilibrium: Used to determine if a population is evolving.

Species Concepts: Biological, morphological, and phylogenetic species concepts.
Prezygotic and Postzygotic Barriers: Mechanisms that prevent species from interbreeding.
Allopatric vs. Sympatric Speciation: Allopatric occurs via geographic isolation; sympatric occurs without physical separation.
Polyploidy: Can lead to speciation, especially in plants.
Gradualism vs. Punctuated Equilibrium: Models describing the tempo of evolutionary change.

Abiotic Synthesis: Formation of organic molecules from inorganic precursors.
Protocells: Simple cell-like structures that may have preceded true cells.
RNA World Hypothesis: Suggests RNA was the first genetic material.
Miller-Urey Experiment: Demonstrated that organic molecules could form under early Earth conditions.
Major Events in Evolution:

Roles in Biosphere: Pathogens, mutualists, decomposers, nutrient cyclers.
Domains: Bacteria, Archaea, Eukarya. Bacteria and Archaea are prokaryotes; Eukarya are eukaryotes.
Transformation and Transduction: Processes by which prokaryotes exchange genetic material, increasing diversity.
Origin of Mitochondria and Chloroplasts: Mitochondria likely arose from proteobacteria; chloroplasts from cyanobacteria.
Nutritional Modes: Photoautotrophs, chemoautotrophs, heterotrophs.
Gram Staining: Technique to differentiate bacterial cell wall types.

Genetic Drift vs. Gene Flow: Genetic drift is random change in allele frequencies; gene flow is movement of alleles between populations.
Bottleneck and Founder Effects: Both reduce genetic diversity; bottleneck is due to drastic reduction in population size, founder effect is when a small group colonizes a new area.
Speciation Scenarios: Understand how reproductive isolation leads to speciation.
Balancing Selection: Maintains genetic diversity in a population.
Phylogenetic Trees: Use shared derived characters to infer evolutionary relationships. Outgroup is a taxon outside the group of interest, used for comparison.

Shared Derived Characters	Lion	Fish	Scorpion	Jellyfish	Sea Urchin
Example Characters	Vertebrate, jaws, four limbs	Vertebrate, jaws	Exoskeleton	Radial symmetry	Radial symmetry, spines
Additional info: Outgroup identification would depend on which characters are shared/absent.	Additional info: Outgroup is the taxon with the fewest shared derived characters.