Honors Biology Terms I–IV Learning Goals

Vocabulary practice flashcards covering essential concepts, biological molecules, ecological principles, genetics, physiology, and evolutionary mechanisms from Terms I through IV of Honors Biology.

CER

A framework for scientific explanation composed of a Claim (an answer to a question), Evidence (scientific data supporting the claim), and Reasoning (a logical explanation connecting the evidence to the claim).

Catabolic Reaction

A metabolic reaction that breaks down complex organic molecules into simpler molecules, releasing energy in the process.

Anabolic Reaction

A metabolic reaction that synthesizes larger, complex molecules from smaller subunits, requiring an input of energy.

Amylase

A digestive enzyme found in saliva and pancreatic secretions that breaks down carbohydrates into simpler sugars.

Pepsin

A digestive enzyme produced in the stomach that hydrolyzes proteins into smaller peptide fragments.

Lipase

A digestive enzyme produced primarily by the pancreas that catalyzes the breakdown of lipids into fatty acids and glycerol.

10% Rule

The ecological principle stating that only approximately 10% of the energy stored as biomass at one trophic level is transferred to the next higher trophic level.

Bioaccumulation

The gradual buildup and accumulation of a chemical or toxin within the tissues of a single individual organism over its lifetime.

Biomagnification

The increasing concentration of persistent toxins in the tissues of organisms at progressively higher trophic levels of a food chain or web.

Keystone Species

A species that exerts strong ecological control on a community structure disproportionate to its abundance or biomass.

Trophic Cascade

An ecological phenomenon triggered by the addition or removal of top predators, resulting in reciprocal changes that propagate down the trophic levels of a food web.

Batesian Mimicry

A defense mechanism in which an innocuous or palatable species evolves to resemble a harmful, noxious, or toxic model species to deter predators.

Müllerian Mimicry

A mutual defense phenomenon where two or more unpalatable, noxious, or harmful species evolve to display similar warning patterns, reinforcing predator avoidance.

Carrying Capacity

The maximum population size of a species that a specific environment can sustainably support over time without environmental degradation.

HIPPCO

An acronym representing the major human-driven causes of extinction and biodiversity loss: Habitat destruction, Invasive species, Population growth, Pollution, Climate change, and Overexploitation.

Tragedy of the Commons

An economic and environmental situation where individuals acting independently in their own self-interest deplete or degrade a shared, open-access natural resource.

Primary Succession

Ecological succession that begins in an essentially lifeless area lacking formed soil, such as exposed rock or new lava flows.

Secondary Succession

Ecological succession that occurs in an area where an existing community has been disturbed or cleared, but the intact soil remains.

Lytic Cycle

A viral reproduction pathway wherein the virus replicates inside a host cell and ultimately causes the host cell to burst (lyse), releasing new viral progeny.

Lysogenic Cycle

A viral reproductive cycle where the viral genetic material is integrated into the host genome and replicated alongside host DNA without immediately destroying the cell.

Hyponatremia

A condition characterized by an abnormally low concentration of sodium in the blood, often caused by excessive water intake that dilutes bodily fluids.

Alveoli

Microscopic, thin-walled air sacs in the lungs where respiratory gas exchange occurs between air and pulmonary capillaries.

Calvin Cycle

The light-independent reactions of photosynthesis occurring in the stroma of chloroplasts that convert carbon dioxide and energy into carbohydrates.

CAM Plants

Plants that conserve water in arid environments by opening stomata to take up carbon dioxide exclusively at night and running the Calvin cycle during the day.

C4 Plants

Plants adapted to hot environments that minimize photorespiration by physically separating initial carbon fixation into mesophyll cells and the Calvin cycle into bundle-sheath cells.

Chargaff's Rule

The biochemical observation that in double-stranded DNA, the percentage of adenine equals thymine ($A = T$) and the percentage of guanine equals cytosine ($G = C$).

Leading Strand

The strand of DNA that is synthesized continuously in the $5' \rightarrow 3'$ direction toward the advancing replication fork.

Lagging Strand

The strand of DNA that is synthesized discontinuously in short Okazaki fragments in the $5' \rightarrow 3'$ direction away from the replication fork.

Totipotent

Stem cells that have the capability to divide and differentiate into any cell type of an organism, including extraembryonic and placental tissues.

Nondisjunction

An error during cell division in which homologous chromosomes or sister chromatids fail to separate properly, resulting in abnormal chromosome numbers in daughter cells.

Epigenetics

The study of inheritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence.

Codominance

A genetic inheritance pattern where both alleles in a heterozygote are fully and simultaneously expressed in the phenotype without blending.

Incomplete Dominance

A genetic inheritance pattern where neither allele is completely dominant, resulting in a heterozygous phenotype that is an intermediate blend of the two homozygous phenotypes.

Epistasis

A phenomenon in genetics where the phenotypic expression of one gene alters or masks the phenotypic expression of a second, independent gene.

Endosymbiotic Theory

The evolutionary theory stating that eukaryotic organelles such as mitochondria and chloroplasts originated as free-living prokaryotes engulfed by ancestral host cells.

Directional Selection

A type of natural selection that favors individuals at one extreme of a phenotypic distribution, shifting the population's phenotypic curve in that direction.

Stabilizing Selection

A type of natural selection that favors intermediate phenotypes and acts against extreme phenotypic variants, decreasing phenotypic diversity in a population.

Disruptive Selection

A type of natural selection that simultaneously favors individuals at both phenotypic extremes over intermediate phenotypes.

Hardy-Weinberg Principle

The principle stating that allele and genotype frequencies in a population will remain constant across generations in the absence of evolutionary forces.

Allopatric Speciation

The formation of new species that occurs when biological populations become geographically separated from each other, preventing gene flow.

Sympatric Speciation

The evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.

Nephron

The microscopic structural and functional filtration unit of the kidney responsible for filtering blood, selective reabsorption, and urine production.

Axial Skeleton

The central framework of the skeletal system comprising the skull, vertebral column, and thoracic cage.

Appendicular Skeleton

The division of the skeleton that includes the bones of the limbs and the pectoral and pelvic girdles that attach the limbs to the axial skeleton.

Hesperidium

A specialized berry with a leathery, aromatic rind and interior sections filled with juice sacs, typical of citrus fruits.