Biology Final Vocabulary

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Analogous structure

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structures that have similar functions and superficially similar appearance but very different anatomies, such as the wings of insects and birds. The similarities are due to similar environmental pressures rather than to common ancestry.

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Artificial selection

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a selective breeding procedure in which only those individuals with particular traits are chosen as breeders; used mainly to enhance desirable traits in domestic plants and animals; may also be used in evolutionary biology experiments

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Catastrophism

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the hypothesis that Earth has experienced a series of geological catastrophes, probably imposed by a supernatural being, that accounts for the multitude of species, both extinct and modern, and preserves creationism

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Convergent evolution

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the independent evolution of similar structures among distantly related organisms as a result of similar environmental pressures

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Evolution

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the descent of modern organisms with modification from preexisting life-forms; strictly speaking, any change in the proportions of different genotypes in a population from one generation to the next

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Fossil

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the remains of a dead organism, normally preserved in rock – may be petrified bones or wood; shells; impressions of body forms, such as feathers, skin, or leaves; or markings made by organisms, such as footprints

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Homologous structure

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structures that may differ in function but that have similar anatomy, presumably because the organisms that possess them have

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Allele frequency

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for any given gene, the relative proportion of each allele of that gene in a population

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Equilibrium population

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a population in which allele frequencies and the distribution of genotypes do not change from generation to generation

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Founder effect

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a type of genetic drift in which an isolated population founded by a small number of individuals may develop allele frequencies that are very different from those of the parent population as a result of chance inclusion of disproportionate numbers of certain alleles in the founders

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Gene pool

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the total of all alleles of all genes in a population; for a single gene, the total of all the alleles of that gene that occur in a population

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Genetic drift

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a change in the allele frequencies of a small population purely by chance

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Hardy – Weinberg principle

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a mathematical model proposing that, under certain conditions, the allele frequencies and genotype frequencies in a sexually reproducing population will remain constant over generations

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Isolating mechanism

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a morphological, physiological, behavioral, or ecological difference that prevents members of two species from interbreeding

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Mutation

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a change in the base sequence of DNA in a gene; normally refers to a genetic change significant enough to alter the appearance or function of the organism

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Natural selection

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the unequal survival and reproduction of organisms due to environmental forces, resulting in the preservation of favorable adaptations. Usually, natural selection refers specifically to differential survival and reproduction on the basis of genetic differences among individuals

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Algae

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any photosynthetic member of the eukaryotic Kingdom Protista

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Anaerobe

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an organism whose respiration does not require oxygen

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Angiosperm

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a flowering vascular plant

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Archaea

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one of life’s three domains; consists of prokaryotes that are only distantly related to members of the domain Bacteria

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Bacteria

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one of life’s three domains; consists of prokaryotes that are only distantly related to members of the domain Archaea

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Bryophyte

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a simple nonvascular plant of the division Bryophyta, including mosses and liverworts

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Cilia

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a short, hair like projection from the surface of certain eukaryotic cells that contains microtubules in a 9 + 2 arrangement. The movement of cilia may propel cells through a fluid medium or move fluids over a stationary surface layer of cells

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Conifer

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a member of a class of tracheophytes that reproduce by means of seeds formed inside cones and that retains its leaves throughout the year

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Endospore

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a protective resting structure of some rod-shaped bacteria that withstands unfavorable environmental conditions

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Eukarya

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one of life’s three domains; consists of all eukaryotes (plants, animals, fungi, and protests)

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Exoskeleton

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a rigid external skeleton that supports the body, protects the internal organs, and has flexible joints that allow for movement

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Flagella

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a long, hair like extension of the plasma membrane; in eukaryotic cells, it contains microtubles arranged in a 9 + 2 pattern. The movement of flagella propel some cells through fluids

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Flower

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the reproductive structure of an angiosperm plant

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Fruit

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in flowering plants, the ripened ovary (plus, in some cases, other parts of the flower), which contains the seeds

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Gymnosperm

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non-flowering seed plant, such as a conifer, cycad or gingko

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Hyphae

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tread like structure that consists of elongated cells, typically with many haploid nuclei; many hyphae make up the fungal body

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Invertebrate

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an animal that never posses a vertebral column (no backbone)

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Larva

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an immature form of an organism with indirect development before metamorphosis into its adult form; includes the caterpillars of moths and butterflies and the maggots of flies

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Metamorphosis

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in animals with indirect development, a radical change in body form from larva to sexually mature adult, as seen in amphibians and insects

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Molt

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to shed an external body covering, such as an exoskeleton, skin, feathers, or fur

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Mycelium

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the body of a fungus, consisting of a mass of hyphae

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Nerve cord

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a paired neural structure in most animals that conducts nervous signals to and from the ganglia; in chordates, an nervous structure lying along the dorsal side of the body; also called spinal cord

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Nitrogen-fixing bacteria

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a bacterium that possesses the ability to remove nitrogen (N2) from the atmosphere and combine it with hydrogen to produce ammonium (NH4+)

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Uniformitarianism

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the hypothesis that Earth developed gradually through natural processes, similar to those at work today, that occur over long periods of time

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Vestigial Structure

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a structure that serves no apparent purpose but is homologous to functional structures in related organisms and provides evidence of evolution

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Population

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all the members of a particular species within an ecosystem, found in the same time and place and actually or potentially interbreeding

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Population bottleneck

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a form of genetic drift in which a population becomes extremely small; may lead to differences in allele frequencies as compared with other populations of the same species and to a loss in genetic variability

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Reproductive isolation

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the failure of organisms of one population to breed successfully with members of another; may be due to premating or postmating isolating mechanisms

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Sexual selection

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a type of natural selection in which the choice of mates by one sex is the selective agent

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Notochord

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a stiff but somewhat flexible, supportive rod found in all members of the phylum Chordata at some stage of development

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Pathogenic

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capable of producing disease; refers to an organism with such a capability (a pathogen)

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Pharyngeal gill slits

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an opening, located just posterior to the mouth, that connects the digestive tube to the outside environment; present (at some stage) in all Chordates

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Phytoplankton

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photosynthetic protists that are abundant in marine and freshwater environments

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Pollen

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the male gametophyte of a seed plant

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Postanal tail

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a tail that extends beyond the anus; exhibited by all chordates at some stage of development

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Protist

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a eukaryotic organism that is not a plant, animal or fungus. The encompasses a diverse array of organism

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protazoa

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a nonphotosynthetic or animal-like protist

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pupa

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a developmental stage in some insect species in which the organism stops moving and feeding and may be encased in a cocoon; occurs betwen teh larval and adult stages

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seed

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the reproductive structure of a seed plant; protected by a seed coat; contains an embryonic plant and a supply of food for it

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spore

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a haploid reproductive cell capable of developing into an adult without fusing with another cell; in the alternation-of-generation life cycle of plants, a haploid cell that is produced by meiosis and then undergoes repeated mitotic divisions and differentation of daughter cells to produce the gametophyte, a multicellular, haploid organism

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vascular plant

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a plant that has specialized structures (vessels) for transporting water and nutrients through its body. Horsetails, ferns, gymnosperms, and flowering plants are examples of vascular plants

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vertebral column

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a column of serially arranged skeletal units (the vertebrate) that enclose the nerve cord in vertebrates; the backbone