Introductory Biology – Taxonomy, Scientific Method & Basic Chemistry

Vocabulary flashcards cover cellular organization, taxonomy, scientific methodology, ant navigation experiment, atomic structure, chemical bonding, and key biochemical terms discussed throughout the lecture.

Prokaryote

Single-celled organism lacking a membrane-bound nucleus; DNA resides in a nucleoid region.

Nucleus (Cell)

Membrane-enclosed compartment in eukaryotic cells that contains chromosomal DNA and is the site of mRNA synthesis.

Nucleoid

Concentrated, non-membranous region of DNA in a prokaryotic cell.

Eukaryote

Organism whose cells possess a true nucleus and other membrane-bound organelles.

Taxon

Any named grouping of organisms in a classification system.

Domain

Highest, most inclusive taxonomic rank (e.g., Bacteria, Archaea, Eukarya).

Kingdom

Taxonomic category below domain and above phylum; part of the mnemonic “King Philip …”.

Phylum (Plural: Phyla)

Major lineage within a domain or kingdom; groups organisms with a shared basic body plan.

Genus

Taxonomic rank above species; first word in a scientific name (italicized and capitalized).

Species

Smallest basic taxonomic unit; group of populations that regularly interbreed and produce viable offspring.

Binomial Nomenclature

Two-word Latin scientific naming system (Genus species), introduced by Linnaeus.

Linnaeus

18th-century scientist who developed the modern hierarchical system of classification and binomial names.

Nucleotide Sequence Comparison

Analyzing DNA bases to determine evolutionary relatedness more accurately than morphology alone.

Hypothesis

Testable, falsifiable statement proposing an explanation for a phenomenon.

Prediction (Science)

Specific, measurable outcome expected if a hypothesis is correct.

Null Hypothesis

Default statement that assumes no effect or relationship; rejected when data support an alternative hypothesis.

Alternative Hypothesis

Research explanation that contrasts with the null; supported when data are inconsistent with the null.

Observational Study

Scientific investigation that gathers data without manipulating variables.

Experimental Study

Investigation in which variables are deliberately manipulated and controls included to test causal relationships.

Sexual Selection

Evolutionary process where traits increase reproductive success by attracting mates or winning contests.

Pedometer Hypothesis (Ants)

Idea that desert ants count steps/stride length to gauge distance back to their nest.

Atom

Smallest unit of an element retaining its chemical properties; composed of protons, neutrons, and electrons.

Atomic Nucleus (Chemistry)

Central region of an atom containing protons and neutrons.

Proton

Positively charged subatomic particle located in the atomic nucleus.

Neutron

Electrically neutral subatomic particle found in the nucleus.

Electron

Negatively charged subatomic particle moving in orbitals around the nucleus.

Atomic Number

Number of protons in an atom; defines the element.

Mass Number

Total number of protons plus neutrons in an atom’s nucleus.

Isotope

Atoms of the same element with different numbers of neutrons (e.g., 12C, 13C, 14C).

Radioactive Isotope

Unstable isotope that decays over time, emitting radiation; useful as biological tracers.

Dalton

Unit of atomic or molecular mass roughly equal to the mass of one proton or neutron.

Electron Shell

Energy level around an atom’s nucleus where electrons reside.

Valence Electron

Electron in the outermost shell; participates in chemical bonding.

Electronegativity

Tendency of an atom to attract shared electrons; oxygen > nitrogen > carbon ≈ hydrogen.

Covalent Bond

Chemical bond formed when two atoms share electron pairs.

Nonpolar Covalent Bond

Covalent bond with equal electron sharing; no charge separation (e.g., C–H in methane).

Polar Covalent Bond

Covalent bond with unequal electron sharing due to electronegativity differences, creating partial charges (e.g., O–H in water).

Partial Charge (δ+ / δ−)

Small fractional electrical charge on atoms in a polar bond caused by unequal electron distribution.

Ionic Bond

Chemical bond formed by complete transfer of electrons, generating oppositely charged ions (e.g., NaCl).

Cation

Positively charged ion formed by losing one or more electrons.

Anion

Negatively charged ion formed by gaining one or more electrons.

Sodium Chloride (Table Salt)

Crystal lattice produced by ionic bonding between Na⁺ and Cl⁻; essential electrolyte.

Hydrogen Ion (H⁺)

Proton produced when a hydrogen atom loses its electron; key to pH and proton gradients.

Bacteria

Domain of prokaryotic organisms distinct from Archaea; evolutionarily older group.

Archaea

Domain of prokaryotic organisms more closely related to eukaryotes than to bacteria.