[adjective] Containing calcium.

[verb - research methods] 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.

[person - matter, physical & chemical properties] An Italian chemist, born in Palermo, Sicily (1826 – 1910). Cannizzaro published a scientific work on atomic theory in 1860 that greatly increased chemists’ understanding and acceptance of Avogadro’s Law.

• Appears in modules:

• Properties of Gases
• The Mole and Atomic Mass

[noun] A technique used to determine the age of an organic object by measuring the amount of the radioactive isotope ¹⁴C in the object. While an organism is alive, it maintains a constant amount of ¹⁴C, but once an organism dies, the ¹⁴C that was present at the time of death decays. Also called ¹⁴C-dating or radiocarbon dating.

[noun] The weak acid formed when CO₂ dissolves in water.

[noun] 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.

• Appears in modules:

• The Nature of Scientific Knowledge

[person - thermodynamics] 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.

• Appears in modules:

• Diffusion I
• The Nature of Scientific Knowledge
• Thermodynamics I

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

• Appears in modules:

• Mendel and Inheritance

[noun] 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.

• Appears in modules:

• Wave Mathematics

[noun - chemical reactions] A substance that speeds up the rate of a chemical reaction but that is not used up in the process.

• Appears in modules:

• Gene Expression
• Mario Molina
• Origins of Life II

[noun] A negatively charged terminal in an electrical cell.

• Appears in modules:

• Atomic Theory I
• The Process of Science

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

• Appears in modules:

• Atomic Theory I
• The Process of Science

[noun] A positively charged ion that migrates to the cathode in an electrical cell.

• Appears in modules:

• Atomic Theory II
• Chemical Bonding
• The Silicate Minerals

[person] 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.

• Appears in modules:

• Gravity

[acronym] An abbreviation for Common Era, which is a designation for the 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.

• Appears in modules:

• Craig Lee
• Data Analysis and Interpretation
• Early Ideas about Matter
• Experimentation in Scientific Research
• Light I
• The Practice of Science
• Utilizing the Scientific Literature
• Waves and Wave Motion

[noun - cells] The basic structural unit of all living things.

• Appears in modules:

• Acids and Bases II
• Animal Behavior
• Barbara McClintock
• Bernardo Houssay
• Blood Biology I
• Cell Division I
• Cell Division II
• Cellular Organelles I
• César Milstein
• Comparison in Scientific Research
• Creativity in Science
• Data Analysis and Interpretation
• David Ho
• Discovery and Structure of Cells
• DNA I
• DNA II
• DNA III
• Energy Metabolism I
• Energy Metabolism II
• Experimentation in Scientific Research
• Exponential Equations in Science II
• Fabiola León-Velarde
• Future of Human Evolution
• Gene Expression
• History of Earth's Atmosphere II
• Introduction to Descriptive Statistics
• Light I
• Linear Equations in Science
• Lipids
• Membranes I
• Membranes II
• Mendel and Independent Assortment
• Mendel and Inheritance
• Meselson and Stahl
• Origins of Life I
• Origins of Life II
• Peer Review in Scientific Publishing
• Plates, Plate Boundaries, and Driving Forces
• Population Genetics
• Santiago Ramón y Cajal and Camillo Golgi
• Scientific Controversy
• Scientists and the Scientific Community
• The Metric System
• The Nitrogen Cycle
• The Phosphorus Cycle
• The Process of Science
• Water
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - materials science, physical & chemical properties] Plant fiber; a polymer (molecular chain) of glucose molecules.

• Appears in modules:

• Ruth Benerito
• Statistics in Science

[person] 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.

[noun] The process of uses a rotating force to separate particles according to density.

• Appears in modules:

• Blood Biology I
• DNA III
• Meselson and Stahl

[noun - biomolecules, cells, genetics & inheritance] Eukaryotic cells depend on organelles known as centrioles to help organize microtubules during cell reproduction (mitosis and meiosis). The centrioles are made of tubulin arranged in a tube-like shape. The centrioles are often in a pair and are arranged at right angles to one another, forming a centrosome.

• Appears in modules:

• Cell Division II

[acronym] See chlorofluorocarbons.

• Appears in modules:

• Mario Molina
• The Practice of Science

[person] English physicist born in Bollington, Cheshire (1891-1974). Chadwick worked with 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.

• Appears in modules:

• Atomic Theory II

[person] (July 10, 1802 - March 17, 1871) 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.

• Appears in modules:

• Charles Darwin III

[person] 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.

• Appears in modules:

• Composition of Earth's Atmosphere

[person] (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.

• Appears in modules:

• Creativity in Science
• DNA II

[noun] A quantity of electricity.

• Appears in modules:

• Atomic Theory I
• Atomic Theory II
• Chemical Bonding
• Chemical Equations
• DNA II
• History of Earth's Atmosphere I
• Light and Electromagnetism
• Lipids
• Membranes I
• Membranes II
• Properties of Liquids
• Properties of Solids
• Solutions, Solubility, and Colligative Properties
• The Nitrogen Cycle
• The Process of Science
• The Silicate Minerals
• Water

[noun - matter, physical & chemical properties, matter, thermodynamics] The relationship between a gas’s volume (V) and its temperature (T), which was first observed by Jacques Charles. Charles’s Law states that for a fixed amount of gas at a constant pressure, the gas’s volume increases linearly as its absolute temperature increases.

[person - matter, physical & chemical properties, matter, thermodynamics] A French scientist and hot-air balloonist, born in Beaugency, France (1746 – 1823). Charles invented and flew in the first hydrogen-filled balloon; while working with hot-air balloons, he observed in 1787 that a gas’s temperature and volume were linearly correlated. This relationship between temperature and volume was later named Charles’s Law by the French scientist Joseph-Louis Gay-Lussac in 1801.

[person] (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.

• Appears in modules:

• DNA I

[noun] A link between atoms. See ionic bond and covalent bond.

• Appears in modules:

• Chemical Bonding
• Energy
• Energy Metabolism I
• Ruth Benerito

[noun] 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.

• Appears in modules:

• Cellular Organelles I
• Chemical Bonding
• Chemical Equations
• Chemical Reactions
• Discovery and Structure of Cells
• DNA I
• Early Ideas about Matter
• Energy
• Energy Metabolism I
• Exponential Equations in Science II
• Factors that Control Earth's Temperature
• Gene Expression
• History of Earth's Atmosphere II
• Linear Equations in Science
• Mario Molina
• Meselson and Stahl
• Modeling in Scientific Research
• Nuclear Chemistry
• Properties of Gases
• The Phosphorus Cycle
• The Rock Cycle
• Thermodynamics I

[noun - biomolecules, cells, organic & biochemistry] The movement of ions along an electrochemical gradient through a membrane. Usually, the term is applied in connection with a proton gradient to generate the energy molecule adenosine triphosphate (ATP) during cellular respiration and photosynthesis.

• Appears in modules:

• Energy Metabolism II

[noun - compounds, atmospheric science, human impacts on the environment] Compounds consisting of carbon, chlorine, fluorine, and sometimes hydrogen once used widely as aerosol propellants and refrigerants. lso known as CFCs. 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.

• Appears in modules:

• Mario Molina

[noun - anatomy & physiology, cells, organisms] Organelle in plant and algae cells where photosynthesis occurs.

• Appears in modules:

• Cellular Organelles I
• Discovery and Structure of Cells
• Energy Metabolism II
• Membranes I
• Photosynthesis I

[noun - biomolecules, cells, genetics & inheritance] Chromatin is the substance inside of the cell's nucleus and it consists of DNA, proteins (primarily histones), and chromosomal RNA. The principal function of chromatin is to package DNA by folding it up into a compact form that, when stained with a dye, can be seen as individual chromosomes. Chromatin is only found in eukaryotic cells.

• Appears in modules:

• Cell Division I
• Cell Division II

[noun - cells, genetics & inheritance] The organized genetic structure of DNA with associated proteins that contains the hereditary information necessary for reproduction, protein manufacture, and other functions.

• Appears in modules:

• Barbara McClintock
• Cell Division I
• Cell Division II
• Cellular Organelles I
• Creativity in Science
• DNA I
• Gene Expression
• Mendel and Inheritance
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - atmospheric science, oceanography, weather & climate, weather & climate] Generally, movement within a system. 1. [Atmospheric] the movement of air masses within the troposphere, driven by the redistribution of energy from the sun and the rotation of the Earth. 2. [Oceanic] the movement of water in Earth’s oceans driven by surface winds, Earth’s rotation, and density differences.

• Appears in modules:

• Cell Division II
• Composition of Earth's Atmosphere
• Factors that Control Regional Climate
• Kevin Arrigo
• Modeling in Scientific Research
• Scientific Controversy
• The Hydrologic Cycle

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

• Appears in modules:

• Adaptation

[noun - scientific tools & techniques] 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 datasets. Others help by reporting things like rainfall or bird species observed in their backyard. 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.

• Appears in modules:

• Sergio Avila

[noun - taxonomy & systematics] In biology, the arranging of groups of organisms into sets or divisions on the basis of their evolutionary relationships.

• Appears in modules:

• Plates, Plate Boundaries, and Driving Forces
• Properties of Minerals
• Taxonomy I
• Theories, Hypotheses, and Laws

[person - thermodynamics] (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.

• Appears in modules:

• Kinetic-Molecular Theory
• The Nature of Scientific Knowledge
• Thermodynamics I

[noun - rock cycle] Breakage in crystal structure of certain minerals along planes where atomic bonds are weakest.

• Appears in modules:

• Properties of Minerals
• The Silicate Minerals

[noun - atmospheric science, weather & climate, human impacts on the environment, weather & climate] Climate describes the average and patterns of a particular area’s weather over time. Climate includes such elements as temperature, precipitation, humidity, sunshine, wind velocity, and other measures of the weather. Weather, on the other hand, is the description of short-term atmospheric changes.

• Appears in modules:

• Adaptation
• Animal Behavior
• Biodiversity I
• Carlos J. Finlay
• Charles Darwin I
• Comparison in Scientific Research
• Composition of Earth's Atmosphere
• Craig Lee
• Data Analysis and Interpretation
• Description in Scientific Research
• Factors that Control Earth's Temperature
• Factors that Control Regional Climate
• Franklin Chang Díaz
• Introduction to Descriptive Statistics
• Introduction to Inferential Statistics
• Introduction to Paleoanthropology
• Kevin Arrigo
• Luis Walter Alvarez
• Mario Molina
• Modeling in Scientific Research
• Origins of Plate Tectonic Theory
• Peer Review in Scientific Publishing
• Percy Lavon Julian
• Ruth Benerito
• Scientific Controversy
• Scientific Institutions and Societies
• Scientists and the Scientific Community
• Solutions, Solubility, and Colligative Properties
• Stoichiometry
• The Carbon Cycle
• The Hydrologic Cycle
• The Nitrogen Cycle
• The Process of Science
• The Rock Cycle
• Unit Conversion
• Using Graphs and Visual Data in Science
• Utilizing the Scientific Literature

[noun - atoms & subatomic particles, matter, atoms & subatomic particles, forces, matter] The interaction of a molecule with other molecules of the same substance due to intermolecular forces such as hydrogen bonding. For example, rain falls in droplets due to cohesive forces between water molecules.

• Appears in modules:

• Properties of Liquids
• Water

[noun - chemistry] A theory used to predict the rate at which chemical reactions occur and the factors that affect these reactions. Collision theory is based on the assumption that for two reactants to enter into a reaction to form products, they must first come together through a collision. Reactants that do not collide, or collide with insufficient energy will not react.

[noun - matter, physical & chemical properties] A mixture in which minuscule insoluble particles are distributed in a liquid and remain dispersed in the liquid. Homogenized milk is an example of a colloid. Compare to suspension.

• Appears in modules:

• Properties of Liquids

[noun - chemical reactions, energy, thermodynamics] 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).

• Appears in modules:

• Carbon Chemistry
• Chemical Reactions

[adjective - data, research methods] Identifying similarities and differences.

• Appears in modules:

• Comparison in Scientific Research
• Description in Scientific Research
• Experimentation in Scientific Research
• Modeling in Scientific Research
• Statistics in Science
• The Practice of Science

[noun - compounds, organic & biochemistry] A material formed by the chemical combination of elements in defined proportions. Compounds can be chemically decomposed into simpler substances.

• Appears in modules:

• Atomic Theory IV
• Bernardo Houssay
• Blood Biology I
• Cell Division II
• Chemical Bonding
• Chemical Equations
• Chemical Reactions
• Defining Minerals
• Density
• Discovery and Structure of Cells
• DNA I
• Early Ideas about Matter
• Energy Metabolism I
• Experimentation in Scientific Research
• Exponential Equations in Science II
• Fats and Proteins
• Gene Expression
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Mario Molina
• Measurement
• Membranes II
• Modeling in Scientific Research
• Percy Lavon Julian
• Properties of Liquids
• Properties of Minerals
• Properties of Solids
• Ruth Benerito
• The Mole and Atomic Mass
• The Nitrogen Cycle
• The Phosphorus Cycle
• The Silicate Minerals
• Theories, Hypotheses, and Laws
• Unit Conversion

[noun] The amount of one substance in relation to other components within a given area.

• Appears in modules:

• Acids and Bases I
• Acids and Bases II
• Blood Biology I
• Comparison in Scientific Research
• Composition of Earth's Atmosphere
• Data Analysis and Interpretation
• Description in Scientific Research
• Diffusion I
• Experimentation in Scientific Research
• Factors that Control Earth's Temperature
• Factors that Control Regional Climate
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Kevin Arrigo
• Linear Equations in Science
• Lipids
• Luis Walter Alvarez
• Mario Molina
• Membranes II
• Meselson and Stahl
• Modeling in Scientific Research
• Origins of Life II
• Properties of Liquids
• Santiago Ramón y Cajal and Camillo Golgi
• Scientific Ethics
• Scientific Notation and Order of Magnitude
• Solutions, Solubility, and Colligative Properties
• The Carbon Cycle
• The Phosphorus Cycle
• The Rock Cycle

[noun - biomolecules, cells, organic & biochemistry] The difference in molecule concentration inside and outside of the cell across a cell membrane.

• Appears in modules:

• Diffusion I
• Membranes II

[noun - anatomy & physiology] 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.

[noun - physical & chemical properties] A substance formed by condensation, such as a liquid from a gas.

• Appears in modules:

• Experimentation in Scientific Research
• States of Matter

[noun - weather & climate, weather & climate] The process of forming a liquid from a gas.

• Appears in modules:

• States of Matter
• The Hydrologic Cycle

[noun - chemical reactions, energy, materials science, physical & chemical properties, hydrology & fresh water, oceanography, energy resources, nutrient cycles, electromagnetism, energy, matter, thermodynamics] A measurement of a substance’s ability to transmit (or conduct) heat, sound, or electricity. For example, copper exhibits high conductivity in relation to the transfer of heat or electricity.

In aquatic science, conductivity is a measurement of water’s ability to conduct electricity. Along with salinity (the measurement of salt dissolved in a volume of water), conductivity provides information on what kinds of dissolved solids are in the water. Water with a high concentration of inorganic salts, for example, will conduct electricity much faster than water with a lower concentrations.

• Appears in modules:

• Properties of Solids
• The Phosphorus Cycle

[noun - science communication] A large, formal meeting where many people gather for a particular purpose, such as to talk about research in a certain field of science.

• Appears in modules:

• Data Analysis and Interpretation
• David Ho
• Mario Molina
• Peer Review in Scientific Publishing
• Scientific Ethics
• The How and Why of Scientific Meetings
• The Piltdown Hoax

[noun - statistics] A type of interval estimate commonly used by scientist to report a plausible range of values for a population parameter based on a subsample dataset. The confidence interval is named after the fact that its construction relies on choosing a confidence level that reflects the degree of uncertainty associated with the estimation. The confidence level represents the percentage of confidence intervals that can be expected to include the true population parameter if all possible confidence intervals were calculated from all possible subsamples.

• Appears in modules:

• Confidence Intervals
• Uncertainty, Error, and Confidence

[noun - statistics] In statistics, the confidence level reflects the degree of uncertainty associated with a parameter estimation, particularly the calculation of a confidence interval. Higher confidence levels reflect less uncertainty while lower confidence levels reflect more uncertainty. Scientists often use a 95% confidence level.

• Appears in modules:

• Confidence Intervals
• Statistics in Science

[noun - atoms & subatomic particles] The way parts are arranged, such as how electrons are distributed in orbitals, or electron shells, around the nucleus of an atom.

• Appears in modules:

• Atomic Theory IV
• Carbon Chemistry
• Chemical Bonding
• Creativity in Science
• DNA II
• Lipids
• The Periodic Table of Elements

[noun - ethics, science & decision making] 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.

• Appears in modules:

• Introduction to Paleoanthropology
• The Piltdown Hoax

[noun] A curve formed by the intersection of a cone with a plane. This often results in a circle, ellipse, or parabola.

• Appears in modules:

• Gravity

[acids, bases & pH] Conjugate acid: In an acid-base reaction, the conjugate acid is the species that results when the original base accepts a proton from the original acid.

H2CO3 + H2O <--> H3O+ + HCO3

Here, H3O+ is the conjugate acid, having accepted a proton and being able to donate one.

• Appears in modules:

• Acids and Bases II

[acids, bases & pH] In an acid-base reaction, the conjugate base is the species that results when the original acid donates a proton to the original base.

H2CO3 + H2O <--> H3O+ + HCO3

Here, HCO3 is the conjugate base, having donated a proton and being able to accept one.

• Appears in modules:

• Acids and Bases II

[noun] 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.

• Appears in modules:

• Atomic Theory II
• Chemical Equations
• Chemical Reactions
• Early Ideas about Matter
• Membranes I
• Modeling in Scientific Research
• Sergio Avila
• The Hydrologic Cycle
• Thermodynamics I

[noun - evolution & adaptation, organisms, taxonomy & systematics, biodiversity & ecological relationships, human impacts on the environment, organisms, scientific concepts] 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?" (http://www.michaelsoule.com/resource_files/85/85_resource_file1.pdf) and visit the Society for Conservation Biology (http://www.conbio.org). To learn about global efforts to conserve biodiversity, explore the United Nations Convention on Biological Diversity (http://www.cbd.int).

• Appears in modules:

• Sergio Avila

[noun] In mathematics, a quantity that has a fixed value; something that does not vary.

• Appears in modules:

• Animal Behavior
• Atomic Theory III
• Atomic Theory IV
• Biodiversity I
• Chemical Equations
• Composition of Earth's Atmosphere
• Diffusion I
• Exponential Equations in Science I
• Exponential Equations in Science II
• Gravity
• Light and Electromagnetism
• Linear Equations in Science
• Mendel and Inheritance
• Origins of Plate Tectonic Theory
• The Mole and Atomic Mass
• The Nature of Scientific Knowledge

[noun] 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.

• Appears in modules:

• Earth Structure
• Plates, Plate Boundaries, and Driving Forces

[noun] 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. 

• Appears in modules:

• Origins of Plate Tectonic Theory
• Plates, Plate Boundaries, and Driving Forces

[noun - research methods] 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 Experimentation in Scientific Research.

• Appears in modules:

• Animal Behavior
• Cell Division I
• Charles Darwin II
• DNA I
• Experimentation in Scientific Research
• Kevin Arrigo
• Scientific Ethics
• Scientists and the Scientific Community
• Statistics in Science
• The Carbon Cycle
• The Phosphorus Cycle
• Uncertainty, Error, and Confidence

[noun - science & decision making] An argument, disagreement, or difference of opinion that involves many people. A true scientific controversy involves a sustained debate within the broader scientific community with a significant number of people actively engaged in research that addresses the issue over time.

• Appears in modules:

• Earth Structure
• Experimentation in Scientific Research
• Light I
• Membranes I
• Meselson and Stahl
• Scientific Controversy
• The Mole and Atomic Mass
• Understanding Scientific Journals and Articles

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

• Appears in modules:

• Earth Structure
• Factors that Control Regional Climate
• Plates, Plate Boundaries, and Driving Forces
• The Rock Cycle

[noun - seismology & plate tectonics] A plate boundary where two plates are moving towards each other.

[person] 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.

• Appears in modules:

• Taxonomy II

[person] (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.

• Appears in modules:

• Gravity
• The Practice of Science

[noun] 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.

• Appears in modules:

• Atomic Theory II
• Biodiversity I
• Cell Division I
• Cellular Organelles I
• Chemical Bonding
• Comparison in Scientific Research
• Craig Lee
• Creativity in Science
• Discovery and Structure of Cells
• DNA II
• Earth Structure
• Energy
• Factors that Control Earth's Temperature
• Modeling in Scientific Research
• Scientific Controversy
• The Process of Science
• Waves and Wave Motion

[noun - atmospheric science, forces] The apparent deflection of objects in motion with respect to a rotating reference frame.

• Appears in modules:

• Factors that Control Regional Climate

[noun] 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.

• Appears in modules:

• Introduction to Inferential Statistics
• Scientists and the Scientific Community
• Statistics in Science
• The Hydrologic Cycle
• The Phosphorus Cycle

[person - genetics & inheritance] (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.

• Appears in modules:

• Mendel and Independent Assortment

[person] (1485 – December 2, 1547) 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.

• Appears in modules:

• Taxonomy I

[noun - biomolecules, medicine, organic & biochemistry] One of the hormones synthesized in the adrenal cortex. It stimulates synthesis of glucose from protein and fat and suppresses inflammation and immunity.

• Appears in modules:

• Bernardo Houssay
• Lipids
• Membranes I
• Percy Lavon Julian

[noun - cosmology] (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.

• Appears in modules:

• The Nature of Scientific Knowledge

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

• Appears in modules:

• Atomic Theory I

[noun - atoms & subatomic particles] 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 nonpolar covalent bonds. Compare to ionic bond and hydrogen bond.

• Appears in modules:

• Chemical Bonding
• Energy Metabolism I
• Properties of Liquids
• Properties of Solids

[noun - atoms & subatomic particles] 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.

[noun - cells, medicine, organisms] A sustained and involuntary contraction of the muscle.

• Appears in modules:

• Energy Metabolism II
• Membranes II

[person] 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.

• Appears in modules:

• Creativity in Science
• DNA II
• DNA III
• Origins of Life I

[acronym - biomolecules, cells, genetics & inheritance] Stands for "clustered regularly interspaced short palindromic repeats," often associated with "CRISPR-associated sequences" or Cas. Component of an adaptive immune system that protects prokaryotes against viruses. Researchers are using modified CRISPR-Cas systems to edit the genomes of organisms. The CRISPR system most commonly used in genome editing is CRISPR-Cas9.

• Appears in modules:

• Future of Human Evolution

[noun - environmental policy, human impacts on the environment, organisms, science & decision making] In the context of the US Endangered Species Act, the geographic area that is essential to conserving a threatened or endangered species. The US 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.

• Appears in modules:

• Sergio Avila

[noun] 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.

• Appears in modules:

• Defining Minerals
• Earth Structure
• Energy
• History of Earth's Atmosphere I
• Linear Equations in Science
• Luis Walter Alvarez
• Origins of Plate Tectonic Theory
• Plates, Plate Boundaries, and Driving Forces
• Properties of Minerals
• Properties of Solids
• The Rock Cycle
• The Silicate Minerals
• Theories, Hypotheses, and Laws

[noun] 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.

• Appears in modules:

• Creativity in Science
• Defining Minerals
• Description in Scientific Research
• Diffusion I
• Factors that Control Earth's Temperature
• Luis E. Miramontes
• Origins of Plate Tectonic Theory
• Percy Lavon Julian
• Properties of Liquids
• Properties of Minerals
• Properties of Solids
• Santiago Ramón y Cajal and Camillo Golgi
• States of Matter
• Temperature
• The Rock Cycle
• The Silicate Minerals

[adjective - materials science, matter] Having a regular, lattice-like arrangement of atoms or molecules. Crystalline solids melt at a precise melting point and break along specific planes and at specific angles defined by the crystal’s geometry.

• Appears in modules:

• Properties of Liquids
• Properties of Solids
• The Silicate Minerals

[noun] 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).

• Appears in modules:

• Santiago Ramón y Cajal and Camillo Golgi

[person] 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.

• Appears in modules:

• France Anne-Dominic Córdova
• Nuclear Chemistry

[person] French physicist born in Paris (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."

• Appears in modules:

• Nuclear Chemistry

[noun - hydrology & fresh water, oceanography, weather & climate, energy, fluid mechanics & hydraulics] a flow, as of electricity or water. In oceanography and hydrology, a channel of water that flows together at the same velocity

• Appears in modules:

• Animal Behavior
• Atomic Theory I
• Biodiversity I
• Diffusion I
• Discovery and Structure of Cells
• Energy
• Factors that Control Regional Climate
• History of Earth's Atmosphere I
• Kinetic-Molecular Theory
• Light and Electromagnetism
• Measurement
• Origins of Life I
• Peer Review in Scientific Publishing
• Properties of Solids
• Scientific Controversy
• The Process of Science

[noun - cells] The process of cell division in the eukaryotic cell cycle, characterized by the cytoplasm dividing to form two daughter cells.

• Appears in modules:

• Cell Division I
• Cell Division II
• Discovery and Structure of Cells

[noun - cells] 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.

• Appears in modules:

• Blood Biology I
• Cell Division I
• Cellular Organelles I

[noun - cells] The fluid portion of the cytoplasm that is in every animal and plant cell. It surrounds all of the organelles of a cell. Most of the cell's metabolism takes place in the cytosol. It is made of water and fibrous proteins that play an important role in signal transduction pathways and act as intracellular receptors.

• Appears in modules:

• Discovery and Structure of Cells