all the organisms in a given area, along with the non-living factors with which they interact; a biological community and its physical environment.
an assemblage of all the organisms living together and potentially interacting in a particular area.
a basic unit of living matter separated from its environment by a plasma membrane; the fundamental structural unit of life.
new properties that emerge with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.
an organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, alga, or autotrophic prokaryotes.
an organism that obtains its food by eating plants or by eating animals that have eaten plants.
a type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains bacteria and archaea.
a type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. all organisms except bacteria and archaea are composed of eukaryotic cells.
a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA. most of the genes of a eukaryote are located in its chromosomal DNA; a few are carried by the DNA of mitochondria and chloroplasts.
a group whose members possess similar anatomical characteristics and have the ability to interbreed and produce viable, fertile offspring.
a taxonomic category above the kingdom level. the three domains of life are archaea, bacteria, and eukarya.
descent with modification; the idea that living species are descendants of ancestral species that were different from present day ones; also the genetic changes in a population over generations.
a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics.
a tentative explanation a scientist proposes for a specific phenomenon that has been observed.
a widely accepted explanatory idea that is broad in scope and supported by a large body of evidence.
a component of the process of science whereby a scientist carries out two parallel tests, an experimental test and control test.