77Glossary biodiversity – biological diversity; the diversity of species, genes, and/or ecosystems. bipedal – walking on two legs. carrying capacity – the number of a given species that an area can support without impairing its ability to continue supporting that population. DNA – deoxyribonucleic acid. Large molecules in cells that carry the genetic information in living organisms. ecosystem – a community of different species interacting with one another and with the chemical and physical factors making up their non-living environment. ethics – a system of moral principles. fertilizer – substance that adds organic or inorganic nutrients to soil and improves its ability to grow crops, trees, or other vegetation. flux – the rate of flow of particles, fluid, or energy. gene – coded units of information (segments of DNA molecules) about specific traits that are passed on from parents to offspring during reproduction. Ha – hectare, equivalent to 10,000 m2 or 2.471 acres. habitat – place or type of place where an organism or a population of organisms lives. hypothesis – educated guess as to the outcome of an experiment. kg – kilogram, equivalent to 1000 grams Mt – metric tons nutrient – any atom, ion, or molecule an organism needs to live, grow, or reproduce. overpopulation – when long term carrying capacity is being degraded by its current occupants. parameter – a constant aspect of an environment that determines a specific part of that environment but not its general nature.78photosynthesis – the process by which plants use sunlight to combine carbon dioxide and water to produce carbohydrates and oxygen. phytoplankton – small drifting plants, mostly algae, that live in aquatic systems. population – group of individual organisms of the same species living within a particular area. primary productivity – the rate at which plants photosynthesize religion – a specific fundamental set of beliefs and practices generally agreed upon by a number of persons or sects. respiration – process that occurs in the cells of living organisms in which sugars or carbohydrates combine with oxygen to produce carbon dioxide and water and energy. trait – a distinguishing characteristic or quality. transgenic – having a gene(s) from another organisms through the biotechnological transfer of DNA. treatment – an experimental manipulation of the immediate environment surrounding an organism. yr – year zero population growth – the state of equilibrium reached when birth and death rates are the