Biology Final
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626 terms
Terms | Definitions |
|---|---|
 genetics | the scientific study of heredity and hereditary variations |
| self-fertilization | the fusion of sperm and egg produced by the same individual organism |
| cross-fertilization | the fusion of sperm and egg derived from two different individuals |
| true-breeding | referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents; the organisms are homozygous for the characteristics under consideration |
| hybrid | the offspring of parents of two different species or of two different varieties of one species; the offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes |
| cross | hybrid |
| F1 generation | the offspring of two parental (P generation) individuals; F1 stands for first filial |
| F2 generation | the offspring of the F1 generation; F2 stands for second filial |
| monohybrid cross | an experimental mating of individuals differing at one genetic locus |
| allele | an alternative form of a gene |
| homozygous | having two identical alleles for a given gene |
| heterozygous | having two different alleles for a given gene |
| dominant allele | in a heterozygote, the allele that determines the phenotype with respect to a particular gene |
| recessive allele | in a heterozygous individual, the allele that has no noticeable effect on the phenotype |
| law of segregation | a general rule in inheritance that individuals have two alleles for each gene and that when gametes form by meiosis, the two alleles separate, and each resulting gamete ends up with only one allele of each gene; also known as Mendel's first law of inheritance |
| Punnett square | a diagram used in the study of inheritance to show the results of random fertilization |
| phenotype | the expressed traits of an organism |
| genotype | the genetic makeup of an organism |
| dihybrid cross | an experimental mating of individuals differing at two genetic loci |
| law of independent assortment | a general rule of inheritance that when gametes form during meiosis, each pair of alleles for a particular characteristic segregate independently; also known as Mendel's second law of inheritance |
| testcross | the mating between an individual of unknown genotype for a particular characteristic and an individual that is homozygous recessive for that same characteristic |
| rule of multiplication | a rule stating that the probability of a compound event is the product of the separate probabilities of the different ways |
| rule of addition | a rule stating that the probability that an event can occur in two or more alternative ways is the sum of the separate probabilities of the different ways |
| pedigree | a family tree representing the occurrence of heritable traits in parents an offspring across a number of generations |
| carrier | an individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder |
| cystic fibrosis | a genetic disease that occurs in people with two copies of a certain recessive allele; characterized by an excessive secretion of mucus and vulnerability to infection; fatal if untreated |
| inbreeding | mating between close relatives |
| achondroplasia | a form of human dwarfism caused by a single dominant allele; the homozygous condition is lethal |
| Huntington's disease | a human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10-20 years after the onset of symptoms |
| amniocentesis | a technique for diagnosing genetic defects while a fetus is in the uterus; a sample of amniotic fluid, obtained via a needle inserted into the amnion, is analyzed for telltale chemicals and defective fetal cells |
| chorionic villus sampling | (CVS) a technique for diagnosing genetic defects while the fetus is in the uterus; a small sample of the fetal portion of the placenta is removed and analyzed |
| ultrasound imaging | a technique for examining a fetus in the uterus; high-frequency sound waves echoing off the fetus are used to produce an image of the fetus |
| complete dominance | a type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable |
| incomplete dominance | a type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa) |
| ABO blood group | genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells; the phenotypes, also called blood types, are A, B, AB, and O |
| codominance | inheritance pattern in which a heterozygote expresses the distinct trait of both alleles |
| pleiotropy | the control of more than one phenotypic characteristic by a single gene |
| polygenic inheritance | the additive effect of two or more gene loci on a single phenotypic characteristic |
| chromosome theory of inheritance | a basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns |
| linked genes | genes located on the same chromosome that tend to be inherited together |
| recombination frequency | with respect to two given genes, the number of recombinant progeny from a mating divided by the total number of progeny; recombinant progeny carry combinations of alleles different from those in either of the parents as a result of independent assortment of chromosomes or crossing over |
| sex chromosome | a chromosome that determines whether an individual is male or female |
| sex-linked gene | a gene located on a sex chromosome |
| red-green color blindness | a category of common, sex-linked human disorders involving several genes on the X chromosome; characterized by a malfunction of light-sensitive cells in the eyes; affects mostly males but also homozygous females |
| hemophilia | a human genetic disease caused by a sex-linked recessive allele; characterized by excessive bleeding following injury |
| Duchenne muscular dystrophy | a human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue |
| bacteriophage | a virus that infects bacteria; also called a phage |
| phage | bacteriophage |
| nucleotide | an organic monomer consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group; they are the building blocks of nucleic acids |
| polynucleotide | a polymer made up of many nucleotides covalently bonded together |
| sugar-phosphate backbone | the alternating chain of sugar and phosphate to which the DNA and RNA nitrogenous bases are attached |
| thymine | (T) a single-ring nitrogenous base found in DNA |
| cytosine | (C) a single-ring nitrogenous base found in DNA and RNA |
| adenine | (A) a double-ring nitrogenous base found in DNA and RNA |
| guanine | (G) a double-ring nitrogenous base found in DNA and RNA |
| uracil | (U) a single-ring nitrogenous base found in RNA |
| double helix | the form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape |
| semiconservative model | type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand |
| DNA polymerase | an enzyme that assembles DNA nucleotides into polynucleotides using a preexisting strand of DNA as a template |
| DNA ligase | an enzyme, essential for DNA replication, that catalyzes the covalent bonding of adjacent DNA nucleotides; used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector |
| transcription | the synthesis of RNA on a DNA template |
| translation | the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule; there is a change of "language" from nucleotides to amino acids |
| triplet code | a set of three-nucleotide-long words that specify the amino acids for polypeptide chains; genetic code |
| codon | a three-nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination signal; the basic unit of the genetic code |
| genetic code | the set of rules giving the correspondence between nucleotide triplets (codons) in mRNA and amino acids in protein |
| RNA polymerase | an enzyme that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template |
| promoter | a specific nucleotide sequence in DNA, located at the start of a gene, that is the binding site for RNA polymerase and the place where transcription begins |
| terminator | a special sequence of nucleotides in DNA that marks the end of a gene; it signals RNA polymerase to release the newly made RNA molecule, and then to depart from the gene |
| messenger RNA | (mRNA) the type of ribonucleic acid that encodes genetic information from DNA and conveys it to ribosomes, where the information is translated into amino acid sequences. |
| intron | in eukaryotes, a nonexpressed (noncoding) portion of a gene that is excised from the RNA transcript. |
| exon | in eukaryotes, a coding portion of a gene. |
| RNA splicing | the removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence; occurs before mRNA leaves the nucleus. |
| transfer RNA | (tRNA) a type of ribonucleic acid that functions as an interpreter in translation. Each tRNA molecule has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA. |
| anticodon | on a tRNA molecule, a specific sequence of three nucleotides that is complimentary to a codon triplet on mRNA. |
| ribosomal RNA | (rRNA) the type of ribonucleic acid that, together with proteins, makes up ribosomes; the most abundant type of RNA. |
| start codon | on mRNA, the specific three-nucleotide sequence (AUG) to which an initiator tRNA molecule binds, starting translation of genetic information. |
| P site | one of two of a ribosome's binding sites for tRNA during translation. It holds the tRNA carrying the growing polypeptide chain. (P stands for peptidyl tRNA.) |
| peptide bond | the covalent linkage between two amino acid units in a polypeptide; formed by a dehydration reaction. |
| translocation | during protein synthesis, the movement of tRNA molecule carrying a growing polypeptide chain from the A site to the P site on a ribosome. (The mRNA travels with it.) |
| stop codon | in mRNA, one of the three triplets (UAG, UAA, UGA) that signal gene translation to stop. |
| mutation | a change in the nucleotide sequence of DNA; the ultimate source of genetic diversity. |
| reading frame | the way in which a cell's mRNA-translating machinery groups the mRNA nucleotides into codons. |
| mutagenesis | the creation of a mutation |
| mutagen | a chemical or physical agent that interacts with DNA and causes a mutation. |
| capsid | the protein shell that encloses a viral genome. It may be rod-shaped, polyhedral, or more complex in shape. |
| lytic cycle | a type of viral replication cycle resulting in the release of a new viruses by lysis (breaking open) of the host cell. |
| lysogenic cycle | a type of bacteriophage replication cycle in which the viral genome is incorporated into the bacterial host chromosome as a prophage. New phages are not produced, and the host cell is not killed or lysed unless the viral genome laves the host chromosome. |
| prophage | phage DNA that has inserted by genetic recombination into the DNA of a prokaryotic chromosome. |
| emerging virus | a virus that has appeared suddenly or has recently come to the attention of medical scientists. |
| reverse transcriptase | an enzyme that catalyzes the synthesis of DNA on an RNA template. |
| retrovirus | an RNA virus that reproduces by means of a DNA molecule. It reverse-transcribes its RNA into DNA, inserts the DNA into a cellular chromosome, and then transcribes more copies of the RNA from the viral DNA. HIV and a number of cancer-causing viruses are this. |
| AIDS | acquired immune deficiency syndrome; the late stages of HIV infection, characterized by a reduced number of T cells and the appearance of characteristic secondary infections. |
| HIV | human immunodeficiency virus, the retrovirus that attacks the human immune system and causes AIDS. |
| transformation | the incorporation of new genes into a cell from DNA that the cell take up from the surrounding environment. |
| transduction | the transfer of bacterial genes from one bacterial cell to another by a phage. |
| conjugation | the union (mating) of two bacterial cells or protists cells and the transfer of DNA between two cells. |
| plasmid | a small ring of DNA separate from the chromosome(s). It's found in prokaryotes and yeast. |
| R plasmid | a bacterial plasmid that carries genes for enzymes that destroy particular antibiotics, thus making the bacterium resistant to the antibiotics |
| clone | the collection of cells, organisms, or molecules resulting from cloning; also, a single organism that is genetically identical to another because it arose from the cloning of a somatic cell |
| gene expression | the process whereby genetic information flows from genes to proteins; the flow of genetic information from the genotype to the phenotype |
| promoter | a specific nucleotide sequence in DNA, located at the start of a gene, that is the bonding site for RNA polymerase and the place where transcription begins |
| operator | in prokaryotic DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach; the binding of a repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon |
| operon | a unit of genetic regulation common in prokaryotes; a cluster of genes with related functions, along with the promoter and operator that control their transcription |
| repressor | a protein that blocks the transcription of a gene or operon |
| regulatory gene | a gene that codes for a protein, such as a repressor, that controls the transcription |
| activator | a protein that switches on a gene or group of genes |
| differentiation | the specialization in the structure and function of cells that occurs during the development of an organism; results from selective activation and deactivation of the cells' genes |
| regeneration | the regrowth of body parts from pieces of an organism |
| histone | a small protein molecule associated with DNA and important in DNA packaging in the eukaryotic chromosome |
| nucleosome | the bead-like unit of DNA packaging in a eukaryotic cell; consists of DNA wound around a protein core made up of eight histone molecules |
| X chromosome inactivation | in female mammals, the inactivation of one X chromosome in each somatic cell |
| transcription factor | in the eukaryotic cell, a protein that functions in initiating or regulating transcription; they bind to DNA or to other proteins that bind to DNA |
| enhancer | a eukaryotic DNA sequence that helps stimulate the transcription of a gene at some distance from it; it functions by means of a transcription factor called an activator, which binds to it and then to the rest of the transcription apparatus |
| alternative RNA splicing | a type of regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns |
| nuclear transplantation | a technique in which the nucleus of one cell is placed into another cell that already has a nucleus or in which the nucleus has been previously destroyed |
| embryonic stem cell (ES cell) | cell in the early animal embryo that differentiates during development to give rise to all the different kinds of specialized cells in the body |
| adult stem cell | a cell present in adult tissues that generates replacements for nondividing differentiated cells |
| homeotic gene | a master control gene that determines the identity of a body structure of a developing organism, presumably by controlling the developmental fate of groups of cells |
| homeobox | a 180-nucleotide sequence within a homeotic gene and some other developmental genes |
| oncogene | a cancer-causing gene; usually contributes to malignancy by abnormally enhancing the amount or activity of a growth factor made by the cell |
| proto-oncogene | a normal gene that can be converted to a cancer-causing gene |
| tumor-suppressor gene | a gene whose product inhibits cell division, thereby preventing uncontrolled cell growth |
| carcinogen | a cancer-causing agent, either high-energy radiation (such as X-rays or UV light) or a chemical |
| DNA technology | methods used to study and/or manipulate DNA, including recombinant DNA technology |
| recombinant DNA technology | techniques for synthesizing recombinant DNA in vitro and transferring it into cells, where it can be replicated and may be expressed; also known as genetic engineering |
| plasmid | a small ring of DNA separate from the chromosome(s); these are found in prokaryotes and yeast |
| gene cloning | the production of multiple copies of a gene |
| recombinant DNA | a DNA molecule carrying genes derived from two or more sources |
| clone | a group of identical cells descended from a single ancestral cell |
| genetic engineering | the direct manipulation of genes for practical purposes |
| biotechnology | the use of living organisms (often microbes) to perform useful tasks; today, usually involves DNA technology |
| restriction enzyme | a bacterial enzyme that cuts up foreign DNA, thus protecting bacteria against intruding DNA from phages and other organisms; used in DNA technology to cut DNA molecules in reproducible ways |
| restriction fragments | molecules of DNA produced from a longer DNA strand cut up by a restriction enzyme; used in genome mapping and other applications |
| DNA ligase | an enzyme, essential for DNA replication, that catalyzes the covalent bonding of adjacent DNA nucleotides; used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector |
| vector | in molecular biology, a piece of DNA, usually a plasmid or a viral genome, that is used to move genes from one cell to another |
| genomic library | a set of DNA segments from an organism's genome; each segment is usually carried by plasmid or phage |
| reverse transcriptase | an enzyme that catalyzes the synthesis of DNA on the RNA template |
| complementary DNA | (cDNA) a DNA molecule made in vitro using mRNA as a template and the enzyme reverse transcriptase; this molecule therefore corresponds to a gene but lacks the introns present in the DNA of the genome |
| vaccine | a harmless varient or derivative of a pathogen used to stimulate a host organism's immune system to mount a long-term defense against the pathogen |
| nucleic acid probe | in DNA technology, a labeled single-stranded nucleic acid molecule used to find a specific gene or other nucleotide sequence within a mass of DNA; it hydrogen-bonds to the complementary sequence in the targeted DNA |
| DNA microarray | a glass slide carrying thousands of different kinds of single-stranded DNA segments arranged in an array (grid); it is used to detect and measure the expression of thousands of genes at one time; tiny amounts of a large number of single-stranded DNA fragments representing different genes are fixed to the glass slide; these fragments, ideally representing all the genes of an organism, are tested for hybridization with various samples of cDNA molecules |
| gel electrophoresis | a technique for separating and purifying macromolecules; a mixture of molecules is placed on a gel between a positively charged electrode and a negatively charged one; negative charges on the molecules are attracted to the positive electrode, and the molecules migrate toward that electrode; the molecules separate in the gel according to their rates of migration |
| genetic marker | an allele tracked in a genetic study |
| restriction fragment length polymorphisms | (RFLPs) the differences in homologous DNA sequences that are reflected in different lengths of of restriction fragments produced when the DNA is cut up with restriction enzymes |
| forensic science | the scientific analysis of evidence for crime scene and other investigations |
| DNA fingerprint | a procedure that analyzes an individual's unique collection of DNA restriction fragments , detected by electrophoresis and nucleic acid probes; it can be used to determine whether two samples of genetic material are from the same individual |
| gene therapy | a treatment for a disease in which the patient's defective gene is altered |
| polymerase chain reaction | (PCR) a technique used to obtain many copies of a DNA molecule or part of a DNA molecule; a small amount of DNA mixed with the enzyme DNA polymerase |
| Human Genome Project | (HGP) an international collaborative effort to map and sequence the DNA of the entire human genome |
| repetitive DNA | nucleotide sequences that are present in many copies in the DNA of a genome; the repeated sequences may be long or short and may be located next to each other or dispersed in the DNA |
| telomere | the repetitive DNA at each end of a eukaryotic chromosome |
| transposon | a transposable genetic element, or "jumping gene"; a segment of DNA that can move from one site to another within a cell and serve as an agent of genetic change |
| genomics | the study of whole sets of genes and their interactions |
| proteomics | the study of whole sets of proteins and their interactions |
| genetically modified organism | (GMO) an organism that has acquired one or more genes by artificial; if the gene is from another species, the organism is also known as a transgenic organism |
| Ti plasmid | a bacterial plasmid that induces tumors in plant cells that it infects; often used as a vector to introduce new genes into plant cells; Ti stands for tumor-inducing |
| transgenic organism | an organism that contains genes from another species |
| evolutionary adaptation | an inherited characteristic that enhances an organism's ability to survive and reproduce in a particular environment |
| evolution | genetic change in a population or species over generations; all the changes that transform life on Earth; the heritable changes that have produced Earth's diversity of organisms |
| descent with modification | Darwin's initial phrase for the general process of evolution |
| natural selection | differential success in reproduction by different phenotypes resulting from interactions with the environment; evolution occurs when this produces changes in the relative frequencies of alleles in a population's gene pool |
| artificial selection | selective breeding of domesticated plants and animals to promote the occurrence of desirable inherited traits in offspring |
| paleontologist | a scientist who studies fossils |
| fossil record | the chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in the rock strata |
| stratum | a layer of sedimentary rock that was formed as sediments of sand and mud were compressed into rock by overlying deposits |
| biogeography | the study of past and present distribution of species |
| comparative anatomy | the study of the body structures in different organisms |
| homology | anatomical similarity due to common ancestry |
| homologous structures | structures that are similar in different species of common ancestry |
| vestigial organ | a structure of marginal, if any, importance to an organism; they are historical remnants of structures that had important functions in ancestors |
| comparative embryology | the study of the formation, early growth, and development of different organisms |
| molecular biology | the study of the molecular basis of genes and gene expression; molecular genetics |
| population | a group of interacting individuals belonging to one species and living in the same geographic area |
| species | a group whose members possess similar anatomical characteristics and have the ability to interbreed |
| population genetics | the study of genetic changes in populations; the science of microevolutionary changes in populations |
| modern synthesis | a comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution |
| gene pool | all the genes in a population at any one time |
| microevolution | a change in a population's gene pool over a succession of generations; evolutionary changes in species over relatively brief periods of geologic time |
| Hardy-Weinberg equilibrium | the principle that the shuffling of genes that occurs during sexual reproduction, by itself, cannot change the overall genetic genetic makeup of a population |
| genetic drift | a change in the gene pool of a population due to chance |
| bottleneck effect | genetic drift resulting from a drastic reduction in population size |
| founder effect | random change in the gene pool that occurs in a small colony of a population |
| gene flow | the gain or loss of alleles from a population by the movement of individuals or gametes into or out of the population |
| polymorphic | referring to a population in which two or more physical forms are present in readily noticeable frequencies |
| mutation | a change in the nucleotide sequence of DNA; the ultimate source of genetic diversity |
| balancing selection | natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism) |
| heterozygote advantage | greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools |
| frequency-dependent selection | a decline in the reproductive success of a morph's phenotype resulting from the morphiphenotype becoming too common in a population; a cause of balanced polymorphism in populations |
| neutral variation | genetic variation that provides no apparent selective advantage for some individuals over others |
| fitness | the contribution an individual makes to the gene pool of the next generation, relative to the contribution of other individuals in the population |
| stabilizing selection | natural selection that favors intermediate variants by acting against extreme phenotypes |
| directional selection | natural selection that acts against the relatively rare individuals at one end of a phenotypic range |
| disruptive selection | natural selection that favors extreme over intermediate phenotypes |
| sexual dimorphism | a special case of polymorphism based on the distinction between the secondary sex characteristics of males and females |
| cline | a gradation in an inherited trait along a geographic continuum; variation in a population's phenotypic features that parallels an environmental gradient |
| speciation | the evolution of a new species |
| macroevolution | evolutionary change on a grand scale, encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation, and mass extinction |
| taxonomy | the branch of biology concerned with identifying, naming, and classifying species |
| biological species concept | the definition of a species as a population or group of populations whose members have the potential in nature to interbreed and produce fertile offspring; also called a sexual species |
| morphological species concept | the idea that species are defined by measurable anatomical criteria |
| ecological species concept | the idea that ecological roles (niches) define species |
| phylogenetic species concept | the idea that species are defined as a set of organisms with a unique genetic history |
| reproductive barrier | a biological feature of a species that prevents it from interbreeding with other species even when populations of the two species live together |
| temporal isolation | a type of prezygotic barrier between species; the species remain isolated because they breed at different times |
| habitat isolation | a type of prezygotic barrier between species; the species remain isolated because they breed at different habitats |
| behavioral isolation | a type of prezygotic barrier between species; two species remain isolated because individuals of neither species are sexually attracted to individuals of the other species |
| mechanical isolation | a type of prezygotic barrier between species; the species remain isolated because structural differences between them prevent fertilization |
| gametic isolation | a type of prezygotic barrier between species; the species remain isolated because male and female gametes of the different species cannot fuse or they die before they unite |
| hybrid inviability | a type of postzygotic barrier between species; the species remain isolated because hybrid zygotes do not develop or hybrids do not become sexually mature |
| hybrid sterility | a type of postzygotic barrier between species; the species remain isolated because hybrids fail to produce functional gametes |
| hybrid breakdown | a type of postzygotic barrier between species; the species remain isolated because the offspring of hybrids are weak or infertile |
| allopatric speciation | the formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier |
| sympatric speciation | the formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population |
| polyploid | an organism whose cells have more than two complete sets of chromosomes |
| adaptive radiation | the emergence of numerous species from a common ancestor introduced to new and diverse environments |
| gradualism model | the view that evolution occurs as a result of populations becoming isolated from common ancestral stock and gradually becoming genetically unique as they are adapted by natural selection to their local environments; Darwin's view of the origin of species |
| punctuated equilibrium | the idea that speciation occurs in spurts followed by long periods of little change |
| exaptation | a structure that has evolved in one environmental context and later becomes adapted for a different function in a different environmental context |
| evo-devo | the research field that combines evolutionary biology with developmental biology |
| paedomorphosis | the retention of juvenile body features in an adult |
| radiometric dating | a method for determining the age of fossils and rocks from the ratio of a radioactive isotope to the nonradioactive isotope(s) of the same element in the sample |
| continental drift | a change in the position of continents resulting from the incessant slow movement (floating) of the plates of Earth's crust on the underlying molten mantle; it has caused continents to fuse and break apart periodically throughout geologic history |
| Pangaea | the supercontinent consisting of all the major landmasses of Earth fused together; continental drift created this near the end of the Paleozoic era |
| plate tectonics | geologic processes, such as continental drift, volcanoes, and earthquakes, resulting from plate movements |
| phylogeny | the evolutionary history of a group of organisms |
| convergent evolution | adaptive change resulting in nonhomologous (analogous) similarities among organisms; species from different evolutionary lineages come to resemble each other (evolve analogous structures) as a result of living in very similar environments |
| analogy | the similarity of structure between two species that are not closely related; attributable to convergent evolution |
| systematics | an analytical approach to the study of the diversity of life and the evolutionary relationships between organisms |
| binomial | a two-part, latinized name of a species; for example, Homo sapiens (normally italicized) |
| genus | in classification, the taxonomic category above species; the first part of a species' binomial; for example, Homo |
| species | a group whose members possess similar anatomical characteristics and have the ability to interbreed |
| family | in classification, the taxonomic category above genus |
| order | in classification, the taxonomic category above family |
| class | in classification, the taxonomic category above order |
| phylum | in classification, the taxonomic category above class and below kingdom; members of these all have a similar general body plan |
| kingdom | in classification, the broad taxonomic category above phylum or division |
| domain | a taxonomic category above the kingdom level; the three of these of life are Archaea, Bacteria, and Eukarya |
| taxon | a proper name, such as phylum Chordata, class Mammalia, or Homo sapiens, in the taxonomic hierarchy used to classify organisms |
| phylogenetic trees | a branching diagram that represents a hypothesis about evolutionary relationships between organisms |
| cladistics | the study of evolutionary history; specifically, the scientific search for monophyletic taxa (clades), taxonomic groups composed of an ancestor and all its descendants |
| clades | evolutionary branches that consist of an ancestor and all its descendants |
| monophyletic | pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa |
| shared derived characters | homologous features that have changed from a primitive (ancestral) condition and that are unique to an evolutionary lineage; features found in members of a lineage but not found in ancestors of the lineage |
| shared primitive characters | homologous features found in members of a lineage and also in the ancestors of the lineage; ancestral features |
| cladogram | a diagram depicting patterns of shared characteristics among species |
| ingroup | in a cladistic study of evolutionary relationships among taxa of organisms, the group of taxa that is actually being analyzed |
| outgroup | in a cladistic study of evolutionary relationships among taxa of organisms, a taxon or group of taxa with a known relationship to, but not a member of, the taxa being studied |
| parsimony | in scientific studies, the search for the least complex explanation for an observed phenomenon |
| molecular systematics | comparing nucleic acids or other molecules to infer relatedness |
| molecular clock | evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates |
| five-kingdom system | the system of taxonomic classification based on five basic groups: Monera, Protista, Plantae, Fungi, and Animalia |
| three-domain system | the system of taxonomic classification based on three basic groups: Bacteria, Archaea, and Eukarya |
| anthropoid | a member of a primate group made up of the apes (gibbons, orangutans, gorillas, chimpanzees, bonobos, and humans) and monkeys |
| hominoid | a term that refers to great apes, including humans |
| opposable thumb | an arrangement of the fingers such that the thumb can touch the ventral surface of the fingertips of all four fingers |
| paleoanthropology | the study of human origins and evolution |
| hominid | a species on the human branch of the evolutionary tree; a member of the family Hominidae, including Homo sapiens and our ancestors |
| australopith | the first hominids; scavenger-gatherer-hunters who lived on African savannas between about 4.4 million years ago and 1.5 million years ago |
| culture | the ideas, customs, skills, rituals, and similar activities of a people or group that are passed along to succeeding generations |
| ecology | the scientific study of how organisms interact with their environments |
| organism | an individual living thing, such as a bacterium, fungus, protist, plant, or animal |
| community | an assemblage of all the organisms living together and potentially interacting in a particular area |
| ecosystem | all the organisms in a given area, along with the nonliving (abiotic) factors with which they interact; a biological community and its physical environment |
| abiotic component | a nonliving component of an ecosystem, such as air, water, or temperature |
| biotic component | a living component of a biological community; an organism, or a factor pertaining to one or more organisms |
| biosphere | the entire portion of Earth inhabited by life; the sum of all the planet's ecosystems |
| habitat | a place where an organism lives; an environmental situation in which an organism lives |
| tropics | latitudes between 23.5° north and south |
| doldrums | an area of calm or very light winds near the equator, caused by rising warm air |
| trade winds | the movement of air in the tropics (those regions that lie between the 23.5° north latitude and 23.5° south latitude) |
| temperate zones | latitudes between the tropics and the Arctic Circle in the north and the Antarctic Circle in the south; regions with milder climates than the tropics or polar regions |
| prevailing winds | winds that result from the combined effects of Earth's rotation and the rising and falling of air masses |
| westerlies | winds that blow from west to east |
| ocean current | one of the river-like flow patterns in the oceans |
| biome | a terrestrial ecosystem, largely determined by climate, usually classified according to the predominant vegetation and characterized by organisms adapted to the particular environments |
| intertidal zone | a shallow zone where the waters of an estuary or ocean meet land |
| pelagic zone | the region of an ocean occupied by seawater |
| phytoplankton | algae and photosynthetic bacteria that drift passively in aquatic environments |
| zooplankton | animals that drift in aquatic environments |
| benthic zone | a seafloor, or the bottom of a freshwater lake, pond, river, or stream |
| photic zone | the region of an aquatic ecosystem into which light penetrates and where photosynthesis occurs |
| aphotic zone | the region of an aquatic ecosystem beneath the photic zone, where light does not penetrate enough for photosynthesis to take place |
| continental shelf | the submerged part of a continent |
| coral reef | a warm-water, tropical ecosystem dominated by the hard skeletal structures secreted primarily by the resident cnidarians |
| estuary | an area where fresh water merges with seawater |
| wetland | an ecosystem intermediate between an aquatic ecosystem and a terrestrial ecosystem; its soil is saturated with water permanently or periodically |
| tropical forest | a terrestrial biome characterized by warm temperatures year-round |
| savanna | a biome dominated by grasses and scattered trees |
| desert | a biome characterized by organisms adapted to sparse rainfall (less than 30 cm per year) and rapid evaporation |
| desertification | the conversion of semi-arid regions to desert |
| chaparral | a biome dominated by spiny evergreen shrubs adapted to periodic drought and fires; found where cold ocean currents circulate offshore, creating mild, rainy winters, and long, hot, dry summers |
| temperate grassland | a grassland region maintained by seasonal drought, occasional fires, and grazing by large mammals |
| temperate broadleaf forest | a biome located throughout midlatitude regions where there is sufficient moisture to support the growth of large, broadleaf deciduous trees |
| coniferous forests | a biome characterized by conifers, cone-bearing evergreen trees |
| tundra | a biome at the northernmost limits of plant growth and at high altitudes, characterized by dwarf woody shrubs, grasses, mosses, and lichens |
| permafrost | continuously frozen ground found in the tundra |
| population | a group of interacting individuals belonging to one species and living in the same geographic area |
| behavior | everything an animal does and how it does it, including muscular activities such as chasing prey, certain non-muscular processes such as secreting a hormone that attracts a mate, and learning |
| behavioral ecology | the scientific field that studies behavior in an evolutionary context |
| proximate question | in animal behavior, an inquiry that focuses on the environmental stimuli, if any, that trigger a particular behavioral act, as well as the genetic, physiological, and anatomical mechanisms underlying it. |
| ultimate question | in animal behavior, an inquiry that focuses on the evolutionary significance of a behavioral act. |
| innate behavior | behavior that appears to be performed in virtually the same way by all members of a species |
| fixed action pattern | (FAP) a genetically programmed, virtually unchangeable behavioral sequence performed in response to a certain stimulus |
| sign stimulus | in animal behavior, a stimulus that triggers a fixed action pattern |
| learning | modification of behavior as a result of specific experiences |
| habituation | learning not to respond to a repeated stimulus that conveys little or no information |
| imprinting | learning that is limited to a specific critical period in an animal's life and that is generally irreversible |
| sensitive period | a limited phase in an individual animal's development when learning of particular behaviors can take place |
| kinesis | random movement in response to a stimulus |
| taxis | virtually automatic orientation toward or away from a stimulus |
| spatial learning | modification of behavior based on experience of the spatial structure of the environment |
| landmark | a point of reference for orientation during navigation |
| cognitive map | a representation within the nervous system of spatial relations among objects in an animal's environment |
| migration | the regular back-and-forth movement of animals between two geographic areas at particular times of the year |
| associative learning | learning that a particular stimulus or response is linked to a reward or punishment; includes classical conditioning and trial-and-error learning |
| trial-and-error learning | learning to associate a particular behavioral act with a positive or negative effect |
| social learning | modification of behavior through the observation of other individuals |
| cognition | the ability of an animal's nervous system to perceive, store, process, and use information obtained by its sensory receptors |
| foraging | behavior necessary to recognize, search for, capture, and consume food |
| search image | the mechanism that enables an animal to find a particular kind of food efficiently |
| optimal foraging theory | the basis for analyzing behavior as a compromise of feeding costs versus feeding benefits |
| promiscuous | referring to a type of relationship in which mating occurs with no strong pair-bonds or lasting relationships |
| monogamous | referring to a type of relationship in which one male mates with just one female |
| polygamous | referring to a type of relationship in which an individual of one sex mates with several of the other |
| social behavior | any kind of interaction between two or more animals, usually of the same species |
| sociobiology | the study of the evolutionary basis of social behavior |
| agonistic behavior | confrontational behavior involving a contest waged by threats, displays, or actual combat, which settles disputes over limited resources, such as food or mates |
| dominance hierarchy | the ranking of individuals based on social interactions; usually maintained by agonistic behavior |
| signal | a behavior that causes a change in behavior in another animal |
| communication | animal behavior in transmission of, reception of , and response to signals |
| altruism | behavior that reduces an individual's fitness while increasing the fitness of another individual |
| inclusive fitness | the total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to increase the production of their offspring |
| kin selection | a phenomenon of inclusive fitness, used to explain altruistic behavior between related individuals |
| reciprocal altruism | in animal behavior, a selfless act repaid at a later time by the beneficiary or by another member of the beneficiary's social system |
| culture | the ideas, customs, skills, rituals, and similar activities of a people or group that are passed along to succeeding generations |
| territory | an area that one or more individuals defend and from which other members of the same species are usually excluded |
| population ecology | the study of how members of a population interact with their environment, focusing on factors that influence population density and growth |
| population | a group of interacting individuals belonging to one species and living in the same geographic area |
| population density | the number of individuals of a species per unit area of volume |
| dispersion pattern | the manner in which individuals in a population are spaced within their area; three types of this are clumped, uniform, and random |
| clumped | describing a dispersion pattern in which individuals are aggregated in patches |
| uniform | describing a dispersion pattern in which individuals are evenly distributed |
| random | describing a dispersion pattern in which individuals are spaced out in a patternless, unpredictable way |
| life table | a listing of survivals and deaths in a population in a particular time period and predictions of how long, on average, an individual of a given age will live |
| survivorship curve | a plot of the number of members of a cohort that are still alive at each age; one way to represent age-specific mortality |
| intrinsic rate of increase | an organism's inherent capacity to reproduce |
| exponential growth model | a mathematical description of idealized, unregulated population growth |
| limiting factors | environmental factors that restrict population growth |
| logistic growth model | a mathematical description of idealized population growth that is restricted by limited factors |
| carrying capacity | in a population, the number of individuals that an environment can sustain |
| density-dependent | referring to any characteristic that varies according to an increase in population density |
| life history | the series of events from birth through reproduction to death |
| r-selection | the concept that in certain populations, a high reproductive rate is the chief determinant of life history |
| K-selection | the concept that in certain populations, life history is centered around producing relatively few offspring that have a good chance of survival |
| sustainable resource management | management of a natural resource so as not to damage the resource |
| maximum sustained yield | the level of harvest that produces a consistent yield without forcing a population into decline |
| ecological footprint | a method of using multiple constraints, including food, fuel, water, housing, and waste deposits, to estimate the human carrying capacity of the Earth |
| demographic transition | a shift from zero population growth in which birth rates and death rates are high to zero population growth characterized instead by low birth and death rates |
| age structure | the relative number of individuals of each age in a population |
| community | an assemblage of all the organisms living together and potentially interacting in a particular area |
| species diversity | the variety of species that make up a community; concerns both species richness (the total number of different species) and the relative abundance of the different species |
| trophic structure | the feeding relationships in a community; determines the route of energy flow and the pattern and chemical cycling in an ecosystem |
| interspecific competition | competition between individuals or populations of two or more species requiring a limited resource; may inhibit population growth and help structure communities |
| competitive exclusion principle | the concept that populations of two species cannot coexist in a community if their niches are nearly identical. using resources more efficiently and having a reproductive advantage, one of the populations will eventually outcompete and eliminate the other |
| niche | a population's role in its community; the sum total of a population's use of the biotic and abiotic resources of its habitat |
| resource partitioning | the division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species |
| predation | an interaction between species in which one species, the predator, eats the other, the prey |
| predator | a consumer in an biological community |
| prey | an organism eaten by a predator |
| Batesian mimicry | a type of mimicry in which a species that a predator can eat looks like a different species that is poisonous or otherwise harmful to the predator |
| Müllerian mimicry | a mutual mimicry by two species, both of which are poisonous or otherwise harmful to a predator |
| keystone species | a species that is not usually abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche |
| herbivore | an animal that eats only plants or algae |
| coevolution | evolutionary change in which adaptations in one species act as a selective force on a second species, including adaptations that in turn act as a selective force on the first species; mutual influence on the evolution of two different interacting species |
| symbiotic relationship | a close association between organisms of two or more species |
| parasitism | a symbiotic relationship in which the parasite, a type of predator, lives within or on the surface of a host, from which it derives its food |
| pathogens | a disease-causing organism |
| commensalism | a symbiotic relationship in which one partner benefits without significantly affecting the other |
| mutualism | a symbiotic relationship in which both partners benefit |
| disturbance | in an ecological sense, a force that changes a biological community and usually removes organisms from it. These, such as fires and storms, play a pivotal role in structuring many biological communities |
| ecological succession | the process of biological community change resulting from disturbance; transition in the species composition of a biological community, often following a flood, fire, or volcanic eruption |
| primary succession | a type of ecological succession in which a biological community arises in an area without soil |
| secondary succession | a type of ecological succession that occurs where a disturbance has destroyed an existing biological community but left the soil intact |
| food chain | a sequence of food transfers form producers through several levels of consumers in an ecosystem |
| producer | an organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, |
| primary consumer | an organism in the trophic level of an ecosystem that eats plants or algae |
| secondary consumer | an organism that eats primary consumers |
| tertiary consumer | an organism that eats secondary consumers |
| quaternary consumer | an organism that eats tertiary consumers |
| detritivore | an organism that derives its energy from organic wastes and dead organisms |
| decomposer | detritivore |
| detritus | dead organic matter |
| decomposition | the breakdown of organic materials into inorganic ones |
| food web | a network of interconnecting food chains |
| ecosystem | all the organisms in a given area, along with the nonliving (abiotic) factors with which they interact; a biological community and its physical environment |
| energy flow | the passage of energy through the components of an ecosystem |
| chemical cycling | the use and reuse of chemical elements such as carbon within an ecosystem |
| biomass | the amount, or mass, or organic material in an ecosystem |
| primary production | the amount of solar energy converted to chemical energy (organic compounds) by autotrophs in an ecosystem during a given time period |
| conservation biology | the science of species preservation; the scientific study of ways to slow the current high rate of species loss |
| endangered species | as defined in the U.S. Endangered Species Act, a species that is in danger of extinction throughout all or a significant portion of its range |
| threatened species | as defined in the U.S. Endangered Species Act, a species that is likely to become endangered in the foreseeable future throughout all or a significant portion of its range |
| biological magnification | the accumulation of persistent chemicals in the living tissues of consumers in food chains |
| global warming | a slow but steady rise in Earth's surface temperature, caused by increasing concentrations of greenhouse gases (such as CO2 and CH4) in the atmosphere |
| landscape ecology | the application of ecological principles to the study of the structure and dynamics of a collection of ecosystems; the study of the biodiversity of interacting ecosystems |
| movement corridor | a series of small clumps or a narrow strip of quality habitat (usable by organisms) that connects otherwise isolated patches of quality habitat |
| biodiversity hot spot | a small geographic area with an exceptional concentration of endangered and threatened species, especially endemic species (those found nowhere else) |
| endemic species | a species of organism whose distribution is limited to a specific geographic area |
| restoration ecology | the use of ecological principles to develop ways to return degraded ecosystems to conditions as similar as possible to their natural, predegraded state |
| bioremediation | the use of living organisms to detoxify and restore polluted and degrade ecosystems |
| biological augmentation | an approach to restoration ecology that uses organisms to add essential materials to a degraded ecosystem |
| zoned reserve | an extensive region of land that includes one or more areas that are undisturbed by humans; the undisturbed areas are surrounded by lands that have been altered by human activity |
| sustainable development | the long-term prosperity of human societies and the ecosystems that support them |
| stromatolite | rock formed of layered, fossilized, bacterial mats |
| ribozymes | an enzymatic RNA molecule that catalyzes chemical reactions |
| RNA world | a hypothetical period in the evolution of life when RNA served as rudimentary genes and the sole catalytic molecules |
| protobiont | an aggregate of abiotically produced molecules surrounded by a membrane or membrane-like structure |
| pathogens | a disease-causing organism |
| Archaea | one of two prokaryotic domains of life, the other being Bacteria |
| Bacteria | one of two prokaryotic domains of life, the other being Archaea |
| peptidoglycan | a polymer of complex sugars crossed-linked by short polypeptides; a material unique to bacterial cell walls |
| bacillus | a rod-shaped prokaryotic cell |
| pilus | a short projection on the surface of a prokaryotic cell that helps the prokaryote attach to other surfaces |
| endospore | a thick-coated, protected cell produced within a bacterial cell exposed to harsh conditions |
| autotroph | an organism that makes its own food, there by sustaining itself without eating other organisms or their molecules; plants, algae, and photosynthetic bacteria are this |
| photoautotroph | an organism that obtains energy from sunlight and carbon from CO2 by photosynthesis |
| chemoautotroph | an organism that obtains both energy and carbon form inorganic chemicals; this makes its own organic compounds from CO2 without using light energy |
| heterotroph | an organism that cannot makes its own organic food molecules and must obtain them by consuming other organisms or their organic products; an consumer or a decomposer in a food chain |
| photoheterotroph | an organism that obtains energy from sunlight and carbon from organic sources |
| chemoheterotroph | an organism that obtains energy and carbon from organic molecules |
| biofilm | a surface-coating colony of prokaryotes that engage in metabolic cooperation |
| extreme halophile | a microorganism that lives in a highly saline environment, such as the Great Salt Lake or the Dead Sea |
| extreme thermophile | a microorganism that thrives in a hot environment (often 60-80°C) |
| methanogen | a microorganism that obtains energy by using carbon dioxide to oxidize hydrogen, producing methane as a waste product |
| proteobacteria | a diverse clade of gram-negative bacteria that includes five subgroups |
| chlamydia | a group of bacteria that includes a parasite that causes a common sexually transmitted disease |
| spirochete | a large spiral-shaped (curved) prokaryotic cell |
| gram-positive bacteria | bacteria with a cell wall that is structurally less complex and contains more peptidoglycan than that of gram-negative bacteria; these are usually less toxic than gram-negative bacteria |
| cyanobacteria | photosynthetic, oxygen-producing bacteria, formally called blue-green algae |
| exotoxin | a poisonous protein secreted by certain bacteria |
| endotoxin | a poisonous component of the outer membrane of certain bacteria that is released only when the bacteria die |
| Lyme disease | a debilitating human disease caused by the bacterium Borrelia burgdorferi; characterized at first by a red rash at the site of a tick bite and, if not treated, by heart disease, arthritis, and nervous disorders |
| bioremediation | the use of living organisms to detoxify and restore polluted and degraded ecosystems |
| membrane infolding | a proces by which the eukaryotic cell's endomembrane system evolve from inward folds of the plasma membrane of a prokaryotic cell |
| endosymbiosis | a process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger ones |
| symbiosis | an interspecific interaction in which one species, the symbiont, lives in or on another species, the host |
| protist | a member of the kingdom Protista; mostly unicellular, though some are colonial or multicellular |
| alga | one of a great variety of protists, most of which are unicellular or colonial photosynthetic autotrophs with chloroplasts containing the pigment chlorophyll a; heterotrophic and multicellular protists closely related to unicellular autotrophs are also regarded as this |
| protozoan | a protist that lives primarily by ingesting food; a heterotrophic, animal-like protist |
| diplomonad | a protist that has modified mitochondria, two equal-sized nuclei, and multiple flagella |
| euglenozoan | a diverse clade of flagellated protists that includes trypanosones and Euglena |
| dinoflagellate | a unicellular photosynthetic alga with two flagella situated in perpendicular grooves in cellulose plates covering the cell |
| apicomplexan | any of a group of parasitic protozoans, some of which cause human diseases |
| ciliate | a type of protozoan that moves by means of cilia |
| stramenophile | a clade of protists that includes water mold, diatoms, and brown algae and is characterized by a "hairy" flagella |
| water mold | a fungus-like protists in the stramenophile clade |
| diatom | a unicellular photosynthetic alga with a unique, glassy cell wall containing silica |
| brown alga | one of a group of marine, multicellular, autotrophic protists, the most common and largest type of seaweed; this includes the kelps |
| kelp | a giant brown alga, up to 100 m long, that forms extensive undersea forests |
| amoeba | a type of protist characterized by great flexibility and the presence of pseudopodia |
| pseudopodium | a temporary extension of an amoeboid cell; these function in moving cells and engulfing food |
| amoebozoan | a clade of protists that includes amoebas and slime molds and is characterized by lobe-shaped psuedopodia |
| plasmodial slime mold | a type of protist that has amoeboid cells, flagellated cells, and an amoeboid plasmodial feeding stage in its life cycle |
| cellular slime mold | a type of protist that has unicellular amoeboid cells and aggregated reproductive bodies in its life cycle |
| red alga | one of a group of marine, mostly multicellular, autotrophic protists, which includes the reef-building coralline algae |
| green alga | one of a group of photosynthetic protists that includes unicellular, colonial, and and multicellular species; these are plant-like in having biflagellated cells (gametes in colonial and multicellular species), chloroplasts with chlorophyll a, cellulose cell walls, and starch |
| alternation of generations | a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; a characteristic of plants and multicellular green algae |
| gametophyte | the multicellular haploid form in the life cycle of organisms undergoing alternation of generations; mitotically produces haploid gametes that unite and grow into the sporophyte generation |
| sporophyte | the multicellular diploid form in the life cycle of organisms undergoing alternation of generations; results from a union of gametes and meiotically produces haploid spores that grow into the gametophyte generation |
| mycorrhiza | a mutualistic association of plant roots and fungi |
| charophycean | a member of the green algal group that shares two ultrastructural features with land plants; they are considered the closest relatives of land plants |
| Plantae | the kingdom that contains the plants |
| apical meristem | a meristem at the tip of a plant root or in the terminal or axillary bud of a shoot |
| vascular tissue | plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body |
| lignin | a chemical that hardens the cell walls of plants |
| stoma | a pore surrounded by guard cells in the epidermis of a leaf; when these are open, CO2 enters a leaf, and water and O2 exit; a plant conserves water when these are closed |
| gametangium | a reproductive organ that houses and protects the gametes of a plant |
| embryophyte | another name for land plants, recognizing that land plants share the common derived trait of multicellular, dependent embryos |
| sporangium | a capsule in fungi and plants in which meiosis occurs and haploid spores develop |
| spore | in plants and algae, a haploid cell that can develop into a multicellular individual without fusing with another cell |
| bryophyte | one of group of plants that lack xylem and phloem; a nonvascular plant; these include mosses and their close relatives |
| vascular plant | a plant with xylem and phloem |
| seedless vascular plant | the informal collective name for the phyla Lycophyta (club mosses and their relatives) and Pteridophyta (ferns and their relatives) |
| seed | a plant embryo packaged with a food supply within a protective covering |
| gymnosperm | a naked-seed plant; its seed is said to be naked because it is not enclosed in a fruit |
| angiosperm | a flowering plant, which forms seeds inside a protective chamber called an ovary |
| alternation of generations | a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; a characteristic of plants and multicellular green algae |
| gametophyte | the multicellular haploid form in the life cycle of organisms undergoing alternation of generations; mitotically produces haploid gametes that unite and grow into the sporophyte generation |
| sporophyte | the multicellular diploid form in the life cycle of organisms undergoing alternation of generations; results from a union of gametes and meiotically produces haploid spores that grow into the gametophyte generation |
| fossil fuel | an energy deposit formed from the remains of extinct organisms |
| ovule | a reproductive structure in a seed plant; contains the female gametophyte and the developing egg; this develops into a seed |
| pollen grain | the structures that contain the male gametophyte in seed plants |
| sepal | a modified leaf of a flowering plant; a whorl of these encloses and protects the flower bud before it opens |
| petal | a modified leaf of a flowering plant; these are often colorful parts of a flower that advertise it to insects and other pollinators |
| stamen | a pollen-producing male reproductive part of a flower, consisting of a stalk and an anther |
| anther | a sac in which pollen grains develop, located at the tip of a flower's stamen |
| carpel | the female part of a flower, consisting of a stalk with an ovary at the base and a stigma, which traps pollen, at the tip |
| stigma | the sticky part of a flower's carpel, which traps pollen grains |
| ovary | in flowering plants, the basal portion of a carpel in which the egg-containing ovules develop |
| coevolution | evolutionary change in which adaptations in one species act as a selective force on a second species, including adaptations that in turn act as a selective force on the first species; mutual influence on the evolution of two different interacting species |
| Fungi | the kingdom that includes the fungi |
| absorption | the uptake of small nutrient molecules by an organism's own body; the third main stage of food processing, following digestion |
| hypha | one of many filaments making up the body of a fungus |
| heterokaryotic stage | a fungal life cycle stage that contains two genetically different nuclei in the same cell |
| mold | a rapidly growing fungus that reproduces asexually by producing spores |
| yeast | a single-celled fungus that inhabits liquid or moist habitats and reproduces asexually by simple cell division or by the pinching of buds of a parent cell |
| imperfect fungi | a fungus with no known sexual stage |
| chytrid | member of the fungal phylum Chytidiomycota, mostly aquatic fungi with flagellated spores that probably represent the most primitive fungal lineage |
| zygomycete | member of the fungal phylum Zygomycota, characterized by a sturdy structure called a zygosporangium during sexual reproduction; also known as a zygote fungi |
| glomeromycete | member of the fungal phylum Glomeromycota, characterized by a distinct branching form of endomycorrhizae (symbiotic relationships with plant roots) called arbuscular mycorrhizae; also known as an arbuscular mycorrhizal fungus |
| sac fungus | member of the phylum Ascomycota, characterized by saclike structures called asci that produce spores in sexual reproduction; also known as an ascomycete |
| club fungus | member of the phylum Basidiomycota, characterized by a club-shaped, spore-producing structure called a basidium; also known as a basidiomycete |
| mycosis | the general term for a fungal infection |
| lichen | a mutualistic association between a fungus and an alga or between a fungus and a cyanobacterium |
| xylem | The nonliving portion of a plant's vascular system that provides support and conveys ____ sap from the roots to the rest of the plant. This is made up of vessel elements and/or tracheids, water-conducting cells. |
| phloem | the portion of a plant's vascular system that conveys ___ sap throughout a plant. This is made up of sieve-tube members. |
| P generation | the parent individuals from which offspring are derived in studies of inheritance; |
| molecular biology | the study of the molecular basis of genes and gene expression; molecular genetics |
| F factor | a piece of DNA that can exist as a bacterial plasmid; this carries genes for making sex pili and other structures needed for conjugation, as well as a site where DNA replication can start; F stands for fertility |
| therapeutic cloning | the cloning of human cells by nuclear transplantation for therapeutic purposes, such as the replacement of body cells that have been irreversibly damaged by disease or injury |
| signal transduction pathway | a series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell |
| coccus | a spherical prokaryotic cell |
| pollination | in seed plants, the delivery, by wind or animals, of pollen from the male parts of a plant to the stigma of a carpel on the female |
| fruit | a ripened, thickened ovary of a flower, which protects dormant seeds and aids in their dispersal |
| mycelium | the densely branched network of hyphae in a fungus |
| abiotic reservoir | the part of an ecosystem where a chemical, such as carbon or nitrogen, accumulates or is stockpiled outside of living organisms |
| biodiversity | species diversity; the variety of species that make up a community; concerns both species richness (the total number of different species) and the relative abundance of the different species |
| biodiversity crisis | the current rapid decline in the variety of life on Earth, largely due to the effects of human culture |
| ozone layer | the layer of O₃ in the upper atmosphere that protects life on Earth from the harmful ultraviolet rays in sunlight |
| amniote | member of a clad of tetrapods that have an amniotic egg containing specialized membranes that protect the embryo. These include mammals and birds and other reptiles. |
| amniotic egg | a shelled egg in which an embryo develops within a fluid-filled sac and is nourished by yolk; produced by reptiles, birds, and egg-laying mammals, it enables them to complete their life cycles on dry land. |
| amoebocyte | an amoeba-like cell that moves by pseudopodia, found in most animals; depending on the species, may digest and distribute food, dispose of wastes, from skeletal fibers, fight infections, and change into other cell types. |
| amphibian | member of the tetrapode class Amphibia. These include frogs, toads, and salamanders. |
| annelid | a segmented worm. These include earthworms, polychaetes, and leeches. |
| anterior | pertaining to the front, or head, of a bilaterally symmetrical animal. |
| archnid | a member of a major arthropod group (chelicerates) that includes spiders, scorpions, ticks, and mites. |
| arthropod | a member of the most diverse phylum in the animal kingdom. These include the horseshoe crab, arachnids (e.g., spiders, scorpions, ticks, and mites), crustaceans (e.g., crayfish, lobsters, crabs, and barnacles), millipedes, centipedes, and insects. Arthropods are characterized by a chitinous exoskeleton, molting, jointed appendages, and a body formed of distinct groups of segments. |
| bilateral symmetry | an arrangement of body parts such that an organism can be divided equally by a single cut passing longitudinally through it. A bilaterally symmetrical organism has a mirror-image right and left sides. |
| bird | a group of reptiles with feathers and adaptations for flight. |
| blastula | a embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species. |
| centipede | a carnivorous terrestrial arthropod that has one pair of long legs for each of its numerous body segments, with the front pair modified as poison claws. |
| cephalopod | a member of a group of molluscs that includes squids and octopuses. |
| chelicerate | a lineage of arthropods that includes horseshoe crabs, scorpions, ticks, and spiders. |
| choanocyte | a flagellated feeding cell found in sponges. Also called a collar cell, it has a collar cell, it has collar-like ring that traps food particles around the base of its flagellum. |
| chondrichthyan | member of the class Chondrichthyes, vertebrates with skeletons made mostly of cartilage, such as sharks and rays. |
| Chordate | member of the phylum Chordata, animals that at some point during their development have a dorsal hollow nerve cord, a notochord, pharyngeal slits, and a post-anal tail. These include lancelets, tunicates, and vertebrates. |
| circulatory system | the organ system that transport materials such as nutrients, O2, and hormones to body cells and transports CO2 and other wastes from body cells. |
| bilaterian | member of the clade of animals Bilateria exhibiting bilateral symmetry |
| eumetazoan | member of the clade of "true animals," the animals with true tissues (all animals except sponges). |
| closed circulatory system | a circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid. |
| cnidarian | an animal characterized by cnidocytes, radial symmetry, a gastrovascular cavity, and a polyp and medusa body form. These include the hydras, jellyfishes, seas anemones, corals, and related animals. |
| coelom | a body cavity completely lined with mesoderm. |
| complete digestive tract | a digestive tube with two openings, a mouth and an anus. |
| complete metamorphosis | the transformation of a larva into an adult that looks very different from the larva and often functions very differently in its environment. |
| craniate | a chordate with a head. |
| crustacean | a member of a major arthropod group that includes lobsters, crayfish, crabs, shrimps, and barnacles. |
| cuticle | (1) in animals, a tough, nonliving outer layer of the skin. (2) in plants, a waxy coating on the surface of the stems and leaves that help retain water. |
| deuterostomes | an animal with a coelom that forms from hollow outgrowths of the digestive tube of the early embryo. These include the echinoderms and the chordates. |
| dorsal | pertaining to the back of a bilaterally symmetrical animal. |
| dorsal, hollow nerve cord | one of the four hallmarks of chordates. |
| earthworm | a member of one of the three large groups of annelids. |
| echinoderm | member of a phylum of slow-moving or sessile marine animals characterized by a rough or spiny skin, a water vascular system, an endoskeleton, and a radial symmetry in adults. These include sea stars, sea urchins, and sand dollars. |
| ectoderm | the outer layer of three embryonic cell layers in a gastrula; forms the skin of the gastrula and gives rise to the epidermis and nervous system in the adult. |
| ectothermic | referring to organisms that do not produce enough metabolic heat to have much effect of body temperature. |
| endotherm | an animal that derives most of its body heat from its own metabolism. |
| endoskeleton | a hard skeleton located within the soft tissues of an animal; includes spicules of sponges, the hard plates of echinoderms, and the cartilage and bony skeletons of many vertebrates. |
| entomology | the study of insects. |
| eutherian | placental mammal; mammal whose young complete their embryonic development within the uterus, joined to the mother by the placenta. |
| exoskeleton | a hard, external skeleton that protects an animal and provides points of attachment for muscles. |
| flatworm | a member of phylum Platyhelminthes. |
| fluke | one group of parasitic flatworms. |
| foot | in an invertebrate animal, a structure used for locomotion or attachment, such as the muscular organ extending from the ventral side of a mollusc. |
| free-living flatworm | one of a group of nonparasitic flatworms. |
| gastropod | a member of the largest group of molluscs, including snails and slugs. |
| gastrovascular cavity | a digestive compartment with a single opening, the mouth; may function in circulation, body support, waste disposal, and gas exchange, as well as digestion. |
| gastrula | the embryonic stage resulting from gastrulation in animal development. Most animals have a gastrula made up of three layers of cells; ectoderm, endoderm, and mesoderm. |
| horseshoe crab | a bottom-dwelling marine chelicerate, a member of the phylum Arthropoda. |
| hydrostatic skeleton | a skeletal system composed of fluid held under pressure in closed body compartment; the main skeleton of most cnidariams, flatworms, nematodes, and annelids. |
| incomplete metamorphosis | a type of development in certain insects, such as grasshoppers, in which the larvae resemble adults but are smaller and have different body proportions. The animal goes through a series of molts, each time looking more like an adult, until it reaches full size. |
| ingestion | the act of eating; the first main stage of food processing. |
| invertebrate | an animal that lacks a backbone. |
| Animalia | the kingdom that contains the animals. |
| lancelet | one of a group of invertebrate chordates. |
| larva | a free-living, sexually immature form in some animal life cycles that may differ from the adult in morphology, nutrition, and habitat. |
| lateral line system | a row of sensory organs along each side of a fish's body. Sensitive to changes in water pressure, it enables a fish to detect minor vibrations in the water. |
| leech | a member of one of the three large groups os annelids. |
| lobe-fin | a bony fish with strong, muscular fins supported by bones. They are extinct except for one species, the coelacanth. |
| mammal | member of the class Mammalia, aminotes that possess mammary glands and hair. |
| mantle | in a mollusc, the outgrowth of the body surface that drapes over the animal. The mantle produces the shell and forms the mantle cavity. |
| marsupial | a pouched mammal, such as a kangaroo, opossum, or koala. They give birth to embryonic offspring that complete development while housed in a pouch and attached to nipples on the mother's abdomen. |
| medusa | on of two types of cnidarian body forms; an umbrella-like body form. Also called a jellyfish. |
| mesoderm | the middle layer of the three embryonic cell layers in gastrula; gives rise to muscles, cones, and the dermis of the skin, and most other organs in the adult. |
| millipede | a terrestrial arthropod that has two pairs of short legs for each of its numerous body segments and that eats decaying plant matter. |
| mollusc | a soft-bodies animal characterized by a muscular foot, mantle, mantle cavity, an radula; includes gastropods (snails and slugs), bivalves (clams, oysters, and scallops), and cephalopods (squids and octopuses). |
| molting | in arthropods, the process of shedding an old exoskeleton and secreting a new, larger one. |
| monotreme | an egg-laying mammal, such as the duck-billed platypus. |
| nematode | a roundworm, characterized by a pseudocoelom, a cylindrical, wormlike body form, and tough cuticle. |
| notochord | a flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals; present only in embryos in many species. |
| open circulatory system | a circulatory system in which blood is pumped through open-ended vessels and out among the body cells. In an animal with an open circulatory system, blood and interstitial fluid are one and the same. |
| operculum | a protective flap on each side of a fish's head that covers a chamber housing the gills. |
| pharyngeal slit | a gill structure in the pharynx; found in chordate embryos and some adult chordates. |
| placenta | in most mammals, the organ that provides nutrients and oxygen to the embryo and helps dispose of its metabolic wastes; formed of the embryo's chorion and the mother's endometrial blood vessels. |
| placental mammal | mammal whose young complete their embryonic development in the uterus, nourished via the mother's blood vessels in the placenta; also called a eutherian. |
| polychaete | a member of the largest group of annelids. |
| polyp | one of two types of cnidarian body forms; a columnar, hydra-like body. |
| post-anal tail | a tail posterior to the anus; found in the chordate embryos and most adult chordates. |
| posterior | pertaining to the rear, or tail, of a bilaterally symmetrical animal. |
| protostome | an animal with a coelom that develops from solid masses of cells that arise between the digestive tube and the body wall of the embryo. These include the molluscs, annelids, and arthropods. |
| pseudocoelom | a body cavity that is in direct contact with the wall of the digestive tract. |
| radial symmetry | an arrangement of the body parts of an organism like pieces of a pie around an imaginary central axis. Any slice passing longitudinally though radially symmetrical organism's central axis divides it into mirror-image halves. |
| radula | a toothed, rasping organ used to scrape up or shred food; found in many molluscs. |
| ray-finned fish | a bony fish having fins supported by thin, flexible skeletal rays, All but one living species of bony fishes are ray-fins. |
| reptile | member of the clade of amniotes that includes including snakes, lizards, turtles, crocodilians, and birds, along with a number of extinct groups such as dinosaurs. |
| segmentation | subdivision along the length of an animal body into a series of repeated parts called segments. |
| sessile | an organism that is anchored to its substrate. |
| skull | the body framework of the head. |
| sponge | an aquatic animal characterized by a highly porous body. |
| suspension feeder | an animal that extracts food particles suspended in the surrounding water. |
| swim bladder | a gas-filled internal sac that helps bony fishes maintain buoyancy. |
| tapeworm | a parasitic flatworm characterized by the absence of a digestive tract. |
| tunicate | one of a group of invertebrate chordates. |
| ventral | pertaining to the underside, or bottom, of a bilaterally symmetrical animal. |
| vertebrate | a chordate animal with a backbone. Vertebrates include agnathans, cartilaginous fishes, bony fishes, amphibians, reptiles, (including birds and mammals). |
| vertebral column | backbone; composed of a series of segmented units called vertebrae. |
| visceral mass | one of the three main parts of a mollusc, containing most of the internal organs. |
| water vascular system | in echinoderms, a radially arranged system of water-filled canals that branch into extensions called tube feet. The system provides movement and circulates water, facilitating gas exchange and waste disposal. |
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