You can scroll on the bar or click the appropriate letter to find what you would like. Abaxial Facing away from the stem or central axis of a plant or animal. Abiogenesis A theory that living things can develop from nonliving material, as in spontaneous generation. Adaptation The modification of an organism or part of an organism to adjust to new conditions or a new environment, as in adjustment of the eyes to bright light. Adenosine triphosphate (ATP) A chemical compound present in all living cells that provides energy derived from food or sunlight for processes that require activity, such as contraction of a muscle or conduction of a muscle or conduction of a nerve impulse. Appendage A structure attached to a larger structure or part of an organism. Arms, legs and other projections of body areas are examples of appendages. ATP See adenosine triphosphate. Bacteria Tiny, one-celled plant organisms that are generally parasitic and lacking in chlorophyll. They are commonly involved in processes of fermentation and decay, and many species are the cause of diseases in humans and animals. Bladder A saclike organ with a membranous wall that serves to collect or hold a fluid or gas. An example is the urinary bladder or the air bladder of marine animals. Blastula A stage in the development of an embryo after the early phase of cell division when the cells form a hollow ball. The wall of the sphere is a single layer of cells, the blastoderm. The various organs, such as the gut, nervous system, and appendages, eventually evolve from cells of the blastula. Bud An undeveloped appendages of an organism. A plant bud may develop into flowers or leaves while the bud of an animal embryo may become an arm, leg, or wing. Some bacteria and yeast cells reproduce by issuing buds, each of which becomes a new organism. Bug Any of a large number of creeping or flying insects, mainly of the order Hemiptera. Examples of "true bugs" include bed bugs, cinch bugs, squash bugs, and giant water bugs. Calyx A cuplike portion of a plant or animal organ. Examples include the sepals, or outermost parts of a flower, and the funnel-shaped part of a kidney that collects urine as it drains toward the bladder. Carnivore Any meat-eating animal, particularly a member of the order carnivora, which include wolves, coyotes, bears, dogs, and cats. Cell The basic structural unit of living things. It usually consists of a membranous wall containing protoplasm, a soup like mixture of proteins, enzymes, and other organic chemicals needed for survival and reproduction. Most cells also contain a nucleus that in turn holds the DNA molecules, or genetic material, that control the various cell functions. Chlorophyll Any of nearly a dozen kinds of green pigments present in most plant cells. Chlorophylls are able to convert the energy from sunlight into carbohydrates, which plants form from carbon dioxide and water present in the environment. The carbohydrates in turn become a source of energy for animals and humans after the plant material is eaten. Chromosome A rod-shaped unit of DNA present in the nucleus of a cell that is capable of reproducing itself. It contains a portion of the genetic or hereditary traits of the species it represents. The number of chromosomes and their shapes and sizes vary among different species and sexes within a species. Human males, for example, possess a y-shaped chromosome that is not normally present in female cells and that governs masculine physical traits. Deoxyribonucleic acid (DNA) See deoxyribonucleic acid. Embryo The young of a species at a very early state of development, such as the rudimentary plant that bursts forth from a seed when it germinates, or the bird that has not yet hatched from its egg. In mammals, the embryo stage occurs after the cells of the blastula begin to specialize for the development of the fetus. Endogenous Pertaining to factors influencing an organism that originate within that organism, as distinguished from exogenous factors, such as environmental influences, that originate on the outside. Evolution The process by which a species of plants or animals gradually develops over a period of many generations from a simpler to a more complex form or organism. The traits of the simpler organism are often continued into the more complex form of the same organism, as can be observed in the brain and other structures of the human body. Exogenous See endogenous. Fauna The animal life of a region or period of history. Female The sex of an animal that produces ova and bears offspring. Fermentation A process hereby complex carbohydrates or other organic substances are converted to other chemicals by the action of enzymes produced by molds, yeasts, or bacteria. An example is the conversion of sugars to alcohol. Fertilization The union of a male and a female reproductive cell resulting in the formation of a new organism. The term is also used to describe the process or enrichment of the soil for growing crops. Flora The plant life of a region or period of history. Genitalia The reproductive sex organs of a male or female of the species, particularly structures on the outside of the body. Genotype See phenotype. Genus A subdivision of a biological family. It is composed of a group of related species, such as the genus canis, which includes various species of dogs. Gonads The male and female reproductive organs. Haploid Half the number of chromosomes ordinarily present in the nucleus of a cell. During reproduction, the offspring receives a haploid number of chromosomes from each parent, making a full, or diploid, set. Herbaceous Herblike usually used to describe a plant in which persistent woody tissue does not develop. Herbivore An animal that feeds entirely or mainly on plant materials. Hormone A chemical secretion of a gland or other tissue that triggers an action in another gland or tissue in a different part of the body. Immunity A quality of being able to resist an infectious disease. Inbreeding The mating of closely related individuals, as in self-pollinating plants or animals that are brothers and sisters. Joint An area between two parts or segments of an organism, such as the junction of two separate bones of an animal or the node of a plant. Karyotype The general appearance of a set of chromosomes of an individual. Karyotype may be used to determine sex, genetic defects and other chromosome-related factors. Kernel The entire grain or seed of a cereal plant. Larva The young immature form of an organism that undergoes a change in structure to become an adult. The caterpillar and the maggot are examples of larvae. Leaf An outgrowth of a stem of a plant, usually green, in which many living functions, such as photosynthesis, respiration, and food and water storage, take place. Lipid Any of a group of fatty substances, including oils and waxes, produced by plant or animal tissues. Lipids generally are insoluble in water, but they can be dissolved in alcohol, benzene, or similar organic solvents. Male The sex of an animal that produces spermatozoa or of a plant that produces pollen. Mammal A warm-blooded, air-breathing vertebrate of the class Mammalia, possessing hair and mammary glands. Mendel's Laws A series of natural principles of heredity discovered by Gregor Mendel. They govern such factors as dominant and recessive traits resulting from the interaction of genes that are inherited in pairs. Metabolism The chemical and energy changes associated with the consumption of food and oxygen, the production of heat, and the calories used in physical activity. Natural Selection A principle proposed by Charles Darwin to explain the ability of various species to adapt to changes in the environment. Called "survival of the fittest," the theory offered an explanation for the survival of some species and extinction of others. Neuron The structural and functional unit of a nerve, including the cell body and its axon and dendrite fibers. Nucleus A structure present in most plant and animal cells. It contains the chromosomes and ribonucleic acid (RNA) molecules that direct the cell's lie functions. Osmosis The diffusion of water through a semi-permeable membrane from the side with a greater concentration of a solution to the side with a lesser concentration. Osseous Pertaining to bones, as something composed of bone or resembling bone. Phenotype The physical features or appearance of an individual, as distinguished from the genotype, or genetic composition of his or her cells. Two or more people with the same physical appearance may belong to the same phenotype. Pistil The female sex structure of a plant, usually containing the ovary. Protozoa A phylum, or large group, of one-celled animals. Receptor Any cell or group of cells that is the target of a stimulus, such as the retina of the eye. Regeneration The ability of some plants and animals to restore or replace lost tissues or structures, such as a claw or feather. Stamen The pollen-producing structure of a plant. It usually consists of an anther, the actual pollen producer, on the tip of a flower filament. Stimulus An environmental influence, such as a chemical or physical irritant, that induces or brings about a response in a cell or organism. Symbiosis A relationship in which two organisms lives together for the mutual benefit of each. Terrestrial Pertaining to plant or animal life on land rather than in water. Tissue A group of cells with similar structures and functions. Tropism The involuntary response of an organism to a stimulus, such as the response of a plant to gravity or sunlight. Vacuole Any of the spaces scattered about the protoplasm of a cell, usually containing fluid. Zygote The fertilized egg cell of a plant or animal.     COPYRIGHT©2005 VICTORIA PACKING CORP. ALL RIGHTS RESERVED ( CTR-110505-BIO)