| A | B |
|---|
| abiotic | nonliving parts of the environment |
| acid | a compound that releases hydrogen ions when disolved in water. It has a sour taste. |
| acid rain | rain that is more acidic than normal |
| active transport | the process by which cells use energy to transport molecules through the cell membrane from areas of low concentration to areas of high concentration |
| adaptive value | any trait that helps an organism survive and reproduce under a given set of environmental conditions |
| agarose | a gel-like substance used in bacterial cultures |
| AIDS (acquired immunodeficiency syndrome) | the disease that results when the HIV virus attacks the human immune system |
| amino acid | any one of several building blocks of protein |
| antibody | a protein, produced by the immune system, that either attacks invading pathogens or marks them for killing |
| antigen | a molecule found on the outer surfaces of cells that the immune system recognizes as either part of the body or an outside invader |
| artificial selection | the process of breeding two organisms with desirable characteristics to produce offspring that have the advantages of both parents |
| asexual reproduction | a method of reproduction in whichall the genes passed on to the offspring come from a single individual or parent |
| ATP (adenine triphosphate) | a compound that stores energy in cells |
| autotroph | an orgtanism that produces its own foo; the source of energy for all other living things on Earth |
| bacterium (plural is bacteria) | any one of many single-celled organisms without a distinct nucleus |
| biochemical process | a chemical process that occurs in a living thing |
| biodiversity | the variety of species in an area |
| biome | large groups of ecosystems with similar climaates and organisms; exammples include the tundra, taiga, temperate forest, chaparral, tropical rain forest, desert, temperate grassland, etc |
| biotechnology | the combination of technology and biological sciences |
| biotic | the living parts of the environment |
