Glossary
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Bioassay - A bioassay involves use of a biological organism to test for chemical toxicity. Go to the bioassay page for more information.

Biodegradation - "Degradation" means decay, and the "bio-" prefix means that the decay is carried out by a huge assortment of bacteria, fungi, insects, worms, and other organisms that eat dead material and recycle it into new forms.

Bioremediation - "Remediate" means to solve a problem, and "bio-remediate" means to use biological organisms to solve an environmental problem.

Carbon Cycle - The cyclic process in which carbon and its compounds circulate through the biosphere.

Constant - The constants in an experiment are all the factors that do not change. These will vary depending on what question is being addressed. In a bioassay experiment, usually the temperature is kept constant. However, if the question being investigated were, "How does temperature affect lettuce seed germination and growth?" then in this case the temperature would be a variable rather than a constant.

Control - In a scientific experiment, the control is the group that serves as a standard of comparison. It is exposed to the same conditions as the experimental group, except for the variable being tested. In the standard lettuce seed bioassay, the control is the set of seeds grown in distilled water rather than in a test solution.

Daphnia - Daphnia, popularly known as water fleas, are small crustaceans that live in fresh water such as ponds, lakes, and streams.

Deionized Water - Water that is free of all ions, including calcium, sodium, chloride, and all others.

Dependent Variable - A dependent variable in an experiment is a factor that may change as a result of changes purposely made in the independent variable. The number of seeds that germinate and the lengths of their roots are examples of two different dependent variables in bioassay experiments.

Design Challenge - Another form of interactive research is the design challenge, in which students apply skills in mathematical analysis, scientific inquiry, and technological design toward solving a specified problem within certain constraints. Design challenges differ from experiments in that the teacher specifies a specific problem for the students to address.

Ecology - The scientific study of the interactions of living organisms with one another and with their nonliving environment of matter and energy. A plant ecologist might study how maple trees respond to competition from other types of trees, or how maple trees are affected by changing patterns of rainfall.

Environmental Science - The scientific study that uses biological principles to look at the relationships between humans and their environment.

GIS - Geographic Information System.

Hypothesis - An hypothesis is a prediction of the relationship between an independent variable and dependent variable in an experiment. An example hypothesis: "The number of seeds that germinate will decrease with increasing concentration of NaCl."

Independent Variable - An independent variable is a factor that is intentionally varied by the experimenter. In a lettuce seed bioassay, the usual independent variable is the concentration of the solution to which the seeds are exposed.

Organic compounds - Compounds containing chains of carbon and hydrogen atoms.

Peer Review - Peer review means that scientists ask other scientists - that is, their peers - to review their work. In fact, scientists use peer review in all stages of the research process, from narrowing down a question to presenting research results.

pH scale - A scale from 0 to 14 reflecting the concentration of hydrogen ions; the lower numbers denote acidic conditions, 7 is neutral, and the higher numbers denote basic (alkaline) conditions.

Replicate - Replicates are individuals or groups that are exposed to the same conditions in an experiment, including the same level of the independent variable. In a typical bioassay, you might test 5 different solution concentrations. For each of these concentrations, you might use 3 petri dishes, each containing 5 lettuce seeds. At each concentration, the 3 dishes are replicates.

Toxicity - The quality or condition of being toxic; the degree to which a substance is toxic.

Toxicology - Toxicology is the study of the effects of chemicals on living things. We tend to think of some chemicals as toxic and others as nontoxic, but in fact, any chemical is toxic at high enough concentrations.

Toxic Substance - Any substance that can be harmful to plant or animal life; such substances may cause chronic (long-term) toxicity in which harmful levels of the substance accumulate over time, or cause acute toxicity with immediate, harmful effects.

Treatment - A treatment is a factor that affects the outcome of a scientific experiment. In the lettuce seed bioassay, the experimental treatment usually is the concentration of the solution to which the seeds are exposed. If you were testing the effect of temperature on seed germination and growth, the treatment would be temperature rather than solution concentration.

Wastewater Treatment - Wastewater treatment involves using physical, chemical, and/or biological processes to remove harmful pollution - including raw sewage, industrial chemicals, runoff, and more - from wastewater. Wastewater comes from sources such as our homes, business, runoff, or sewers, and after being treated, is typically released into bodies of water such as rivers, lakes, or oceans.

Watershed - The drainage area of a stream, river, or other body of water. For example, all the land in the "Hudson River Watershed" drains into the Hudson River.