Visionlearning Glossary

Containing calcium.

To determine or check the accuracy of an instrument used for quantitative measurements, or to make corrections in or to adjust an aspect of a system.

The weak acid formed when CO₂ dissolves in water.

Used in the following modules: Acids and Bases, The Carbon Cycle

A theoretical formulation of the most efficient thermodynamic cycle capable of converting thermal energy into work, and work into thermal energy. A defining characteristic of the Carnot cycle is that it does not consider a change in entropy, and thus cannot exist in real practice. Like the Third Law of Thermodynamics, the Carnot Cycle serves as a reference point in measuring efficiency and entropy in heat engines.

Used in the following modules: The Nature of Scientific Knowledge

Physicist and military engineer, born in Paris, France (1796-1832). Carnot authored Reflections on the Motive Power of Fire in 1824, which provided the first account of the theoretical workings of heat engines. Carnot’s descriptions of energy transfer within heat engines provided the foundation for the Second Law of Thermodynamics. See Carnot Cycle.

Used in the following modules: The Nature of Scientific Knowledge

(also called Pistil) Female part of a flowering plant consisting of ovary with ovules and stigma/stamen structures to receive pollen.

Used in the following modules: Genetics I

The Cartesian plane, named after the mathematician Rene Descartes, is a plane with a rectangular coordinate system that associates each point in the plane with a unique pair of numbers in an ordered pair of the form (x,y). The x value is the horizontal coordinate and the y value is the vertical coordinate.

Used in the following modules: Wave Mathematics

A negatively charged terminal in an electrical cell.

Used in the following modules: Atomic Theory I, The Process of Science

A negatively charged beam of particles (electrons) that are emitted from the negative terminal in a vacuum tube.

Used in the following modules: The Process of Science

An ion that migrates to the cathode in an electrical cell; a positively charged ion.

Used in the following modules: Minerals III

English chemist and physicist born in Nice, France (1731-1810). Cavendish’s most important work was isolating hydrogen and describing its properties. He also researched electrical capacitance and used a torsion balance (now named for him) to measure the gravitational constant (G), which allowed him to calculate the mass of the Earth. For further information, see Henry Cavendish.

Used in the following modules: Gravity

An abbreviation for Common Era, which is a designation for the period of time beginning with year 1 of the Gregorian calendar. CE is an alternative to the abbreviation AD, and the numbering of years is identical to the Anno Domini system. Compare with BCE.

Used in the following modules: Data: Analysis and Interpretation, Earth Structure, Matter, Research Methods: Experimentation, Research Methods: The Practice of Science, Scientific Communication: Utilizing the Scientific Literature

Swedish astronomer born in Uppsala (1701-1744). In 1742, Celsius invented the centigrade temperature scale, using the freezing and boiling points of water as his reference temperatures. Interestingly, he defined the freezing point as 100° and the boiling point as 0°. The scale was reversed to its present form after his death. Celsius also was the first to suggest that the aurora has a magnetic cause. For further information see Ernest Rutherford on the disintegration of atoms by bombarding them with alpha particles. He was awarded the Nobel Prize in physics in 1935 for his discovery of the neutron. For further information, see James Chadwick.

Used in the following modules: Atomic Theory I

(10 July 1802 – 17 March 1871) was a Scottish author, journal editor and publisher who was highly influential in mid-19th century scientific circles. His most famous book is Vestiges of the Natural History of Creation, published anonymously in 1844, in which he argues for transmutation, an evolutionary view of life similar to that proposed by Jean-Baptiste Lamarck, an unpopular view with both the scientific community and society in general. Charles Darwin credited Chambers with preparing people to accept the theory of evolution by natural selection.

Used in the following modules: Charles Darwin III

British-American geophysicist and mathematician born in Eccles, Lancashire (1888-1970). In 1939, Chapman co-authored the classic work The Mathematical Theory of Non-Uniform Gases. The following year, he co-authored the two-volume work Geomagnetism. His most famous work in mathematics was his research in stochastic processes, for which he developed (independently of Andrey Kolmogorov) the Chapman-Kolmogorov equations. For further information see Sydney Chapman.

Used in the following modules: Earth's Atmosphere

(also known as Edwin Chargaff) Austrian-Jewish biochemist born in Czernowitz, Ukraine (then part of Austria-Hungary) in 1905. Chargaff immigrated to the United States in 1935 and died in New York City in 2002. He is best known for discovering two rules about DNA chemistry that significantly advanced the field of molecular biology. Chargaff’s First Rule is that the number of adenine base units in DNA is equal to that of thymine, and the number of cytosine base units is equal to that of guanine (A = T, C = G). This was an important clue for James Watson and Frances Crick as they worked on solving the molecular structure of DNA. The Second Rule is that the composition of DNA, in terms of the relative amount of A, T, G, and C bases, varies from species to species. This was significant evidence for Oswald Avery’s hypothesis that DNA carries hereditary information. For a more comprehensive biography, see Erwin Chargaff.

Used in the following modules: Creativity in Science, DNA II

(1927 – August 8, 2003), also known as Martha C. Epstein, an American geneticist and member of the team whose experiments showed that DNA, and not protein, comprises genetic material. Chase received her PhD from the University of Southern California in 1964, but her scientific career ended shortly thereafter due to illness, and she suffered from debilitating short-term memory loss until her death in 2003.

Used in the following modules: DNA I

A link between atoms. See ionic bond and covalent bond.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions

A process in which atoms and molecules recombine by forming or breaking chemical bonds. Chemical reactions form new products that have different chemical properties than the initial reacting material.

Used in the following modules: Chemical Equations, Chemical Reactions, Classic Experiment: Meselson and Stahl, DNA I, Fats and Proteins, Matter, Nuclear Chemistry, Research Methods: Modeling, Research Methods: The Practice of Science, The Rock Cycle

Compounds consisting of carbon, chlorine, fluorine, and sometimes hydrogen once used widely as aerosol propellants and refrigerants. The realization that chlorofluorocarbons cause depletion of the stratospheric ozone layer led to a sharp decrease in their use mandated by the Montreal Protocol in 1989.

Used in the following modules: Research Methods: The Practice of Science

The organized genetic structure of DNA with associated proteins that contains the hereditary information necessary for reproduction, protein manufacture, and other functions.

Used in the following modules: Creativity in Science, DNA I, From Stable Chromosomes to Jumping Genes, Genetics I

the system of organs and tissues that circulates blood through an organism, including the heart, blood, arteries, and veins.

Used in the following modules: Adaptation

A person (usually a volunteer or student) who is not a professional scientist but contributes to scientific research. Some citizen scientists assist researchers in analyzing large data sets. Others help by reporting things like rainfall or bird species observed in their backyards. Successful projects, such as those run by the Cornell Lab of Ornithology and the National Weather Service, often rely on volunteers in many locations making repeated observations over time. This can allow citizen science projects to achieve results that a single scientist or small team of researchers could not.

See how citizen scientists have contributed to scientific knowledge through projects at the Cornell Lab of Ornithology and the National Weather Service. Visit the National Science Foundation to learn more about citizen science or explore Scientific American’s list of citizen science projects that need volunteers.

(noun)

Used in the following modules: Tracking Endangered Jaguars with Sergio Avila

In biology, the arranging of groups of organisms into sets or divisions on the basis of their evolutionary relationships.

Used in the following modules: Authoring Modules II, Ideas in Science: Theories, Hypotheses, and Laws, Minerals II, Plate Tectonics II, Taxonomy I

(aka Rudolph Gottlieb) Physicist and mathematician, born in Koszalin, Poland (1822-1888). Clausius authored On the Moving Force of Heat and the Laws of Heat which may be Deduced Therefrom in 1850. This text explored the mechanical theory of heat and the contradictions between the Carnot Cycle and the conservation of energy. In 1865, Clausius provided the first description of, and mathematical formula for entropy.

Used in the following modules: The Nature of Scientific Knowledge

Commonly referred to as burning, a chemical reaction between a fuel (for example wood) and an oxidizing agent (for example oxygen) that produces heat (and usually, light).

Used in the following modules: Organic Chemistry

A material formed by the chemical combination of elements in defined proportions. Compounds can be chemically decomposed into simpler substances.

Used in the following modules: Acids and Bases, Chemical Bonding, Chemical Reactions, Density, Fats and Proteins, Ideas in Science: Theories, Hypotheses, and Laws, Matter, Minerals I, Minerals III, Research Methods: Experimentation, Research Methods: The Practice of Science, The Mole, The Nitrogen Cycle, Water

A type of breakage that produces a smooth, curved surface. Conchoidal fracture occurs when a substance has uniform strength in all directions and no pre-existing planes of atomic weakness. This generally occurs in two types of substances: minerals like quartz whose atomic structure consists of equally strong bonds in all directions, and volcanic glass, called obsidian, which has no definitive crystal structure.

The tendency to search for or interpret new information in a way that confirms one's preconceptions and avoid information and interpretations that contradict prior beliefs.

A curve formed by the intersection of a cone with a plane. This often results in a circle, ellipse or parabola. For more on conic sections, visit Mathworld's Conic Sections lesson.

Used in the following modules: Gravity

Careful use of natural resources to minimize waste or damage to the natural world and to maintain natural resources for long-term human use. Historically, conservation has been contrasted with preservation—a strategy of setting aside resources and wild areas for protection from human impacts. In common usage, though, conservation has come to mean any activity that protects or restores the natural environment.

(noun)

Used in the following modules: Energy, Research Methods: Modeling, The Hydrologic Cycle, Tracking Endangered Jaguars with Sergio Avila

An interdisciplinary branch of science focused on understanding and maintaining Earth's biodiversity and the natural processes that create and sustain it. Conservation biologists study the impacts that humans have on biological diversity (variety) from the genetic level to the whole ecosystem level. They also develop practical ways to protect and restore that diversity.

While it has roots in the older field of ecology, conservation biology is a young scientific discipline. It emerged as its own recognized field of study in the 1980s, though wildlife managers in Australia and Europe had been using the term and practicing some of its tenets (principles) for several decades.

Biologist and founder of the Society for Conservation Biology Michael Soulé wrote one of the first formal explanations of the field in his 1985 paper "What is conservation biology?" Soulé and other early supporters called it a "crisis discipline" because it arose in response to concern over extinction and global loss of biodiversity.

At its core, conservation biology is an applied science with certain goals and values built into it. Like all scientists, conservation biologists seek knowledge about the natural world. But they also suggest ways to apply that knowledge to a real-world problem: biodiversity loss.

Modern conservation biologists draw on wide-ranging disciplines like genetics, physiology, forestry, social science, and many others. They employ a number of tools and approaches in their efforts to study and protect biodiversity. Some of the most common are nature reserves designed to protect species and their habitats and captive breeding programs to help boost wild populations.

Conservation biologists fill many roles, including academic researchers, government wildlife managers and land use planners, breeders at zoos and aquaria, and scientists and advocates working for non-profit groups.

To learn more about the profession and its history, download Soulé's classic paper "What is conservation biology?" and visit the Society for Conservation Biology. To learn about global efforts to conserve biodiversity, explore the United Nations Convention on Biological Diversity.

(noun)

Used in the following modules: Tracking Endangered Jaguars with Sergio Avila

The uppermost layer of the earth that forms the continents. Unlike oceanic crust, continental crust is created and destroyed very slowly, so there is some continental crust on the earth as old as 4 billion years. Continental crust ranges from 10-70 km thick and is composed primarily of granite.

Used in the following modules: Earth Structure, Plate Tectonics II

The theory proposed in 1915 by Alfred Wegener, a German geophysicist and meteorologist. The theory stated that the continents had once been joined into one “supercontinent,” called Pangaea. About 200 million years ago, Pangaea broke apart and the continents drifted to their present positions. Wegener based his theory on the similarity of fossils and rock types on the east coast of South America and the west coast of Africa. The theory was widely ridiculed at the time because Wegener had not proposed a driving force for such drift. 

Used in the following modules: Plate Tectonics I, Plate Tectonics II

In science, a control is a system for which the expected change or outcome is well known and is measured or observed for the purpose of comparing it to a treatment group in scientific research. The control is used as a standard to compare or quantify change in the treatment. For more information, see: Research Methods: Experimentation

Used in the following modules: Adaptation, Charles Darwin II, Data: Statistics, Data: Uncertainty, Error, and Confidence, DNA I, Gravity, Research Methods: Comparison, Research Methods: Experimentation, Research Methods: Modeling, Scientific Communication: Peer Review, Scientific Communication: Understanding Scientific Journals and Articles, Scientific Ethics, Scientists and the Scientific Community, Studying Climate Change with Kevin Arrigo, The Carbon Cycle, Using Science News in Teaching

The movement or circulation of a fluid due to variations in its density as a result of the transfer of heat within the fluid.

Used in the following modules: Earth Structure, Plate Tectonics II, The Rock Cycle

A plate boundary where two plates are moving towards each other.

American paleontologist, born near Philadelphia, Pennsylvania (1840-1897). Cope was a prolific writer and very successful fossil-hunter, publishing over 1200 papers during his career. He developed Cope’s law, stating that mammalian species become larger over time. Cope was especially interested in the natural history of reptiles and amphibians, publishing Bactrachian of North America and The Crocodilians and Snails of North America. Copeia, the leading scientific journal in the field of herpetology is named in his honor. For further information see Edward Drinker Cope.

Used in the following modules: Taxonomy II: Nomenclature

(Mikolaj Kopernik or Nicolaus Koppernigk) Polish astronomer born in Torun in the Royal Prussia region of the Kingdom of Poland (now Poland) (1473-1543). Copernicus was the first European scientist to provide scientific evidence for a heliocentric view of the solar system. In 1543, Copernicus published De revolutionibus orbium coelestium, often considered the origin of the Scientific Revolution. For further information see Nicolaus Copernicus

Used in the following modules: Gravity, Research Methods: The Practice of Science

The innermost layer of the earth, which starts at ~2900 km depth. The core is composed mainly of iron and consists of a molten outer core and a solid inner core.

Used in the following modules: Atomic Theory I, Earth Structure, Educational Web Design, Ideas in Science: Scientific Controversy, Research Methods: Comparison, Scientific Ethics, The Process of Science, Waves and Wave Motion

Correlation, as measured by the correlation coefficient, provides a measure of the strength and direction of a linear relationship between two random variables. While there are many measures of correlation, among the best known is the Pearson product-moment correlation, which ranges from -1 to 1. A correlation coefficient close to -1 indicates a strong negative correlation; a correlation coefficient close to 0 indicates little correlation; and a correlation coefficient close to 1 indicates a strong positive correlation.

Used in the following modules: Data: Statistics, Research Methods: The Practice of Science, Scientists and the Scientific Community, The Hydrologic Cycle

(September 10, 1864 - February 14, 1933) German botanist and geneticist. He is remembered for his independent discovery of the principles of heredity and for his rediscovery of Gregor Mendel's earlier work on that subject. Correns also discovered cytoplasmic inheritance, that is, the influence of extra-chromosomal factors on phenotype. Unfortunately, most of Correns’ work was unpublished and was destroyed when the Allies bombed Berlin in 1945.

Used in the following modules: Genetics II

(1485 – December 2, 1547) was a Spanish conquistador. In the early 16th century, he led the expedition that caused the fall of the Aztec Empire, bringing much of mainland Mexico under the rule of the King of Castile. Cortes used the very effective strategy of making allies with some of the native tribes, and using these allies to attack other native tribes. The King of Castile awarded Cortes the title of Marqués del Valle de Oaxaca for his success in overthrowing the Aztec Empire.

(CMBR) a faint thermal radiation that exists in all of space. Theorized to be residual energy resulting from the Big Bang, this energy fills the Universe almost uniformly.

Used in the following modules: The Nature of Scientific Knowledge

A metric unit of electrical charge equal to the charge on 6.24 × 10¹⁸ electrons.

A very strong chemical bond formed by the sharing of a pair of electrons. Multiple covalent bonds can be formed when multiple pairs of electrons are shared between atoms. Covalent bonds are generally characterized in two types, polar and non-polar covalent bonds. Compare to ionic bond, hydrogen bond.

Used in the following modules: Chemical Bonding

A molecule held together by covalent bonds, that is, pairs of electrons shared between atoms. Covalent molecules are true chemical molecules whose interaction with other molecules is influenced by whether a polar molecule or non-polar molecule is formed.

Used in the following modules: Chemical Bonding, Water

English molecular biologist, physicist, and neuroscientist, most noted for being one of the co-discoverers of the structure of the DNA molecule in 1953. He later contributed to the successful deciphering of the genetic code of DNA. For further information see Francis Crick

Used in the following modules: Creativity in Science, DNA II, DNA III

In the context of the U.S. Endangered Species Act, the geographic area that is essential to conserving a threatened or endangered species. The U.S. Fish and Wildlife Service designates critical habitat in order to protect areas where an endangered species is found and areas with key physical and biological characteristics that will be needed as the species recovers.

(noun)

Used in the following modules: Tracking Endangered Jaguars with Sergio Avila

The uppermost 5-70 km of the earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70 km thick and has a composition approximating that of granite. Oceanic crust, on the other hand, is approximately 5 km thick and has a composition similar to basalt, making it significantly denser than continental crust.

Used in the following modules: Earth Structure, Ideas in Science: Theories, Hypotheses, and Laws, Minerals I, Minerals II, Minerals III, Plate Tectonics I, Plate Tectonics II, The Rock Cycle

A solid of defined shape that is bound by plane surfaces (facets) that intersect at characteristic angles. The shape of a crystal is defined by the bonding and/or interaction between atoms, ions, or molecules that make up the solid. The substances, planar angles and defects in a crystal affect the electrical and optical properties (including color) of the crystal.

Used in the following modules: Chemical Bonding, Creativity in Science, Matter: States of Matter, Minerals I, Minerals II, Minerals III, Plate Tectonics I, Research Methods: Description, The Rock Cycle, Water

The process through which crystals form, resulting in the change from a liquid or vapor to a solid. Crystallization can happen in two basic ways:
1. By lowering the temperature of a melted material like magma or water, atoms and ions start to aggregate into crystals, forming solid rock or ice. This can also happen from a vapor, as is the case with the formation of snowflakes, but it is much less common.
2. By evaporating water from a solution, the saturation point of the water is reached and a solid begins to precipitate out as crystals (for example, salt flats in the desert have been precipitated out of lakes that dried up).

French-Polish physicist and chemist born in Warsaw (1867-1934). Curie was the Head of the Physics Laboratory at the Sorbonne. Working with her husband, Pierre Curie, and inspired by Becquerel’s discovery of radiation, Curie isolated and named the element polonium. She also developed techniques for isolating radium from radioactive residues in order to study its properties. Curie was awarded, with Pierre, half a Nobel Prize in Physics in 1903, for their study of Becquerel radiation. After her husband’s death in 1906, she succeeded him as Professor of General Physics, and was the first woman to hold the post. In 1911 she was awarded a Nobel Prize in Chemistry for her work in radioactivity. For more information see Marie Curie.

Used in the following modules: Nuclear Chemistry

The French physicist born in Paris, France (1859 – 1906 CE). Pioneer in the fields of crystallography, magnetism, and piezoelectricity, he shared the 1903 Nobel Prize in Physics with his wife Marie Curie and with Henri Becquerel for research on the “radiation phenomena.” For further information see: Pierre Curie

A clear, water-based gel that contains enzymes, salts and organic molecules. In eukaryotic cells, cytoplasm surrounds the nucleus and organelles. The role of cytoplasm within the cell is to move materials around and to dissolve cellular waste. It is the primary site for chemical activity in the cell.

Used in the following modules: Cells