Visionlearning Glossary

A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen’s structure that is used to stimulate immunity to a particular disease or antibody production.

Used in the following modules: DNA I

The number of single bonds an atom can form, also measured as the number of hydrogen atoms that typically bond to an atom of an element. For example, in H₂O, oxygen has a valence of two; in CH₄, carbon has a valence of four.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions, Nuclear Chemistry, Organic Chemistry, The Periodic Table of Elements

Electrons that can be actively involved in chemical change; usually electrons in the shell with the highest value of n (electrons in the "outermost" shell of an atom). For example, sodium's ground state electron configuration is 1s² 2s² 2p⁶ 3s¹; the 3s electron is the only valence electron in the atom. Valence electrons determine the chemical properties of an atom and are the only electrons that participate in chemical bonding.

Used in the following modules: Chemical Bonding, Chemical Reactions, Nuclear Chemistry, Organic Chemistry, The Periodic Table of Elements

The outermost electron shell of an atom that contains electrons.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions, The Periodic Table of Elements

To establish the soundness or truth of something, often using an independent means of checking results. Validation of data, models, statistical analyses, etc. is a key component of the process of science.

Used in the following modules: Data: Statistics, Research Methods: Modeling, Scientific Communication: Peer Review, Scientific Ethics

A general term for all attractive forces that occur between electrically neutral molecules. Van der Waals forces include dipole-to-dipole interactions, hydrogen bonds, and other intermolecular forces. For more information on the different types of van der Waals forces, visit "What are van der Waals forces?" at General Chemistry Online.

Used in the following modules: Matter: States of Matter

In science, the term refers to a condition or parameter that may be manipulated, fixed, measured, or observed in the course of scientific research. For more information, see: Research Methods: Experimentation

Used in the following modules: Data: Statistics, Data: Uncertainty, Error, and Confidence, Data: Using Graphs and Visual Data, Earth's Atmosphere, Research Methods: Comparison, Research Methods: Description, Research Methods: Experimentation, Research Methods: Modeling, Research Methods: The Practice of Science, Scientific Communication: Understanding Scientific Journals and Articles, Unit Conversion, Visionlearning

one of the systems of branching vessels conveying deoxygenated blood from various parts of the body to the heart.

Used in the following modules: Adaptation, Minerals III

The speed at which an object is traveling, measured in distance per unit time (for example meters per second or m/s). Compare to acceleration.

Used in the following modules: Earth Structure, The Nature of Scientific Knowledge

(born 1946) American geneticist and entrepreneur, renown for leading the charge to sequence the human genome. While a researcher at the National Institutes of Health (NIH), Venter developed a technique called expressed sequence tags (ESTs) that made rapid sequencing possible. In 1998, he started Celera Genomics, a privately funded company, to pursue genome projects.

Used in the following modules: From Stable Chromosomes to Jumping Genes

any organism with a backbone. Only ~5% of described animal species are vertebrates.

Used in the following modules: Scientific Institutions and Societies, Taxonomy II: Nomenclature

A small sac containing fluid and other material.

Used in the following modules: Absorption, Distribution and Storage of Chemicals

Small protrusions or bumps, usually on the surface of a membrane that increase its surface area.

Used in the following modules: Absorption, Distribution and Storage of Chemicals

English geophysicist, born in London (1939-). With his advisor, Drummond Matthews, Vine wrote “Magnetic Anomalies Over Ocean Ridges,” presenting ideas that helped the theory of plate tectonics gain widespread recognition and adherents. Vine also researched the history of Earth’s magnetic field and studied the electrical conductivity of the lower continental crust. For further information see Frederick Vine.

Polish biologist, born in Scievelbein, Pommerania (today Swindin, Poland) (1821-1902). In 1858 he published his best-known work, The Foundation of Cellular Pathology on the Basis of a Physiological and Pathological Understanding of Tissue, formalizing the cell theory. For further information see Karl Virchow.

an ultramicroscopic infectious agent that can only replicate within the cells of living hosts, mainly bacteria, plants, and animals. Viruses have a very basic structure, consisting of an RNA or DNA core surrounded by a protein coat. More complex viruses also have an envelope surrounding the core and protein coat. Viruses have a wide range of effects on their hosts, from nearly harmless (such as toxoplasmosis in cats) to fatal (such as Ebola in humans).

Used in the following modules: DNA I, Minerals II

(15 November 1871 – 11 October 1962) An Austrian agronomist whose research focused on developing disease-resistant crops, such as wheat-rye and oat hybrids. In 1900, von Seysenegg published a paper presenting his rediscovery of Gregor Mendel’s work on genetics.

Used in the following modules: Genetics II