The Science of Biology

Species

A group of organisms that can interbreed and produce fertile offspring.

Taxonomic Classification

The process of categorizing organisms into hierarchical groups based on shared characteristics.

Taxa

The ranks used in classification, typically ranging from domain to species.

Binomial Nomenclature

A two-part naming system for organisms that includes the genus and species names.

Prokaryotes

Single-celled organisms without a nucleus or membrane-bound organelles.

Eukaryotes

Organisms made up of cells that contain a nucleus and membrane-bound organelles.

Dichotomous Key

A tool used for identifying organisms based on a series of questions that lead the user to the correct name.

Cladogram

A diagram that represents evolutionary relationships among organisms, showing shared derived traits.

Evolution

The change in the heritable characteristics of biological populations over successive generations.

Evidence for Evolution

Fossils, genetic similarities, and comparative anatomy that support the theory of evolution.

Lamarck's Theory

Proposed that organisms evolve through the use and disuse of traits, leading to inherited changes.

Darwin's Theory

Introduced the concept of natural selection as the mechanism by which evolution occurs.

Natural Selection

The process through which traits that enhance survival and reproduction become more common in a population.

Microevolution

Small-scale evolutionary changes within a population.

Macroevolution

Large-scale evolutionary changes that occur over long periods of time, leading to the emergence of new species.

Hardy-Weinberg Principle

States that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences.

Genetic Equilibrium

A state where a population's genetic distribution remains stable over time.

Convergent Evolution

The process where unrelated species evolve similar traits due to similar environmental pressures.

Divergent Evolution

The accumulation of differences between closely related species, leading to the formation of new species.

Homologous Traits

Anatomically similar structures that are inherited from a common ancestor.

Analogous Traits

Structures that serve similar functions but do not share a common evolutionary origin.

Monerans

Microorganisms characterized by prokaryotic cells, including bacteria and archaea.

Viruses

Infectious agents that require a host cell to replicate and do not possess cellular structures.

Lytic Cycle

A viral replication process resulting in the lysing of the host cell.

Lysogenic Cycle

A viral replication process where the viral genome integrates into the host cell's DNA.

Lock-and-Key System

Refers to the specific interaction between a virus and its host cell receptor.

Oviparous Reproduction

A type of reproduction in which organisms lay eggs with little or no other embryonic development within the mother.

Spongin

A fibrous protein that constitutes the skeleton of some sponges.

Osculum

The large opening at the top of a sponge through which water is expelled.

Cephalization

The evolutionary trend of developing a head where sensory organs and nerve cells are concentrated.

Coelom

A fluid-filled body cavity that is completely lined by mesoderm.

Hydrostatic Skeleton

A support structure consisting of a fluid-filled cavity surrounded by muscles.

Amniotic Egg

An egg that contains a protective amniotic membrane, allowing for reproduction in terrestrial environments.

Alternation of Generations

A reproductive cycle in plants involving both a multicellular diploid stage and a multicellular haploid stage.

Rhizoids

Root-like structures that anchor bryophytes but do not perform true root functions.

Meiosis

A type of cell division that reduces the chromosome number by half, producing gametes.

Gametophyte

The haploid generation in the plant life cycle that produces gametes.

Phylum Porifera

The phylum that includes sponges, characterized by a porous body structure.

Phylum Cnidaria

The phylum containing jellyfish, corals, and sea anemones, known for their specialized stinging cells.

Phylum Mollusca

The phylum that includes mollusks, characterized by a soft body and usually a hard shell.

Phylum Arthropoda

The phylum that includes invertebrates with jointed legs and an exoskeleton.

Phylum Echinodermata

The phylum characterized by spiny skin and radial symmetry, including sea stars and sea urchins.

Phylum Chordata

The phylum that includes all animals with a notochord, including vertebrates.