Dr. Overy's KBase: Resources for Teaching and Learning - Glossary

• Causal Link
  A change in one variable that results from or is caused by a change in another variable
• Confounding Variable
  A confounding variable is one that may, in addition to the variable independent variable, affect the outcome of the investigation. Confounding variables must be kept constant or the investigation will not be a fair test. Confounding variables are sometimes referred to as control variables.
• Control Experiment
  A control experiment is one that is set up to eliminate certain possibilities. In a well designed investigation, the independent variable is changed and all confounding variables are kept constant. The possibilityexists, however, that something else other than the independent variable might have produced the results that were obtained. A control experiment is one that is designed to eliminate this possibility
• Control Group
  A control group is one that is treated in exactly the same way as the experimental group except for the factor that is being investigated. This allows scientists to make a comparison. It ensures that the data that are collected are valid because any differences between the results for the experimental group and those for the control group will be due to a single independent variable.
• Correlation
  A correlation shows that there is a relationship between two variables, however, it might not be a causal one
• Double-Blind Trial
  A trial, usually used in the context of medicine, when assessing the effects of a new drug or treatment on humans. Neither the patients nor the scientists concerned know which treatment a particular individual is receiving until after completion of the trial. This helps to avoid bias and increase the validity of the trial.
• Placebo
  A placebo is a dummy pill or injection given to members of a control group in medical trials. Where a placebo is in the form of a pill, it should be identical to the pill used with the experimental group. The only difference should be that that the placebo does not contain the drug being trialled. The use of placebos helps to ensure that the data collected from a trial are valid.
• Probability
  Probability is the likelihood of an event occurring. It differs from chance in that it can be expressed mathematically. In statistical tests, probabilities are usually expressed as a decimal fraction of one. Thus a probability of 0.01 means that an event is likely to occur 1 time in every 100.
• Acid Rain
  Commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. The more accurate term is acid precipitation. Clean or unpolluted rain has a slightly acidic pH of 5.6, the extra acidity in rain comes from the reaction of air pollutants, primarily Sulphur dioxide and Nitrogen oxides, with water in the air to form strong acids (like sulphuric and nitric acid). The main sources of these pollutants are vehicles and industrial and power-generating plants.
• Biodiversity
  The variety of life in all its forms, levels and combinations. This phrase acts as generic terminology for Eco-system diversity, species diversity, and genetic diversity.
• Biodegradable
  Materials that will decompose into naturally occurring, harmless components with exposure to air, sunlight and/or moisture.
• Biofuel
  A fuel produced from dry organic matter or combustible oils produced by plants. Examples of biofuel include alcohol, bio diesel from vegetable oil and wood.
• Biomass
  The total mass of all living organisms within a biological community. Biomass usually refers to plant matter grown for use as Biofuel, but also includes plant or animal matter used for production of fibres, chemicals or heat. Biomass may also include Biodegradable wastes that can be burnt as fuel.
• Biosphere
  The part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life
• Blackwater
  Water from toilets, kitchen sink, or other dirty sources, which could be contaminated with microorganisms or harmful bacteria.
• Carbon dioxide (CO2)
  The greenhouse gas whose concentration is being most affected directly by human activities. The major source of emissions is fossil fuel combustion.
• Carbon Cycle
  The cycle by which carbon is exchanged between the Biosphere, geosphere, hydrosphere and atmosphere of the Earth.
  Major activities include photosynthesis, respiration and decay between atmospheric and terrestrial systems.
• Carbon Footprint
  A measure of the effect that human activities have on the climate in terms of the total amount of Greenhouse gases produced
• Carbon Tax
  A tax on energy sources which emit Carbon dioxide into the atmosphere. It is an example of a pollution tax.
• Climate Change
  Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the atmosphere over time scales ranging from decades to millions of years. These changes may come from processes within the Earth, or be caused by human activities
• Deforestation
  The changes of forested areas to non-forest land use such as arable land, urban use, logged area or wasteland.
• desert
  An area that receives an average annual precipitation of less than 250 mm (9.8 in) or an area in which more water is lost than falls as precipitation
• desertification
  The degradation of land in arid, semi arid and dry sub-humid areas resulting from various climatic variations, but primarily from human activities
• ecosystem
  A dynamic complex of plant, animal and microorganism communities and their non-living environment all interacting as a functional unit.
• endangered species
   A species which is at risk of becoming extinct because it is either few in number, or threatened by changing environmental or predation parameters
• Risk Assessment
  A process which estimates the likelihood that exposed people may have health effects. The four steps of a risk assessment are: hazard identification (Can this substance damage health?); dose-response assessment (What dose causes what effect?); exposure assessment (How and how much do people contact it?); and risk characterization (combining the other three steps to characterize risk and describe the limitations and uncertainties).
• Risk Management
  The process of deciding how and to what extent to reduce or eliminate risk factors by considering the risk assessment, engineering factors (Can procedures or equipment do the job, for how long and how well?), social, economic and political concerns.
• Fossil Fuels
  Fuels such as oil, natural gas, and coal that are made from decayed plants and animals that lived millions of years ago. These fuels are made of hydrogen and carbon (hydrocarbons).
• Greenhouse Gas
  Gases such as carbon dioxide and methane that trap heat in the atmosphere. These gases are emitted from a variety of natural sources like forest fires, and human sources like the combustion of gasoline and natural gas.
• Pollutant
  A contaminant that adversely alters the physical, chemical, or biological properties of the environment