[person - biomolecules] (January 28, 1909 - February 11, 1972) A Canadian-American geneticist. He received his MD from McGill University in 1932, at the age of 23. Working with Oswald Avery and Maclyn McCarty, MacLeod showed that changes in the form or function of bacteria are caused by changes in DNA. The Avery-McCarty-MacLeod experiment was vital in the discovery that genetic material is contained in DNA, not in protein. Later in life, MacLeod became involved in health issues related to the Second World War, such as the microbial diseases typhus fever, malaria, and pneumonia, which posed serious threats to military personnel.

• Appears in modules:

• DNA I

[noun - biomolecules, nutrition, rocks & minerals, energy resources, natural resources, nutrient cycles] Nutrients that are needed in high amounts to sustain life. For example, plants need a high amount of nitrogen, phosphorus, and potassium in order to grow and reproduce. See also: limiting nutrient and micronutrient.

• Appears in modules:

• The Phosphorus Cycle

[adjective - materials science, matter, units of measurement] That which is observable by the unaided eye. Many scientific disciplines explore both large-scale (macroscopic) and tiny (microscopic) properties to fully understand phenomena and organisms. Contrast with microscopic.

• Appears in modules:

• Kinetic-Molecular Theory

[person] (Portuguese: Fernão de Magalhães, ca. 1480 - April 27, 1521) A Portuguese explorer who became a Spanish national so that he could search for a westward route to the Spice Islands (modern Indonesia) for King Charles of Spain. Magellan's expedition of 1519 - 1522 was the first to sail from the Atlantic Ocean to the Pacific Ocean, and the first to cross the Pacific. The expedition completed a circumnavigation of the globe, but Magellan was killed in battle in the Philippines. Magellan named the Pacific Ocean (from Latin, meaning the peaceful ocean), which he reached via what he named the Straits of Magellan. He also named the Magellanic penguin; he was the first European to describe it. He is remembered as one of the great explorers, and the Magellanic clouds, nearby dwarf galaxies visible from the southern hemisphere are named after him.

• Appears in modules:

• Taxonomy I
• The Nature of Scientific Knowledge

[noun - seismology & plate tectonics] Molten rock below the surface of the Earth.

• Appears in modules:

• Defining Minerals
• Description in Scientific Research
• Origins of Plate Tectonic Theory
• Plates, Plate Boundaries, and Driving Forces
• Properties of Minerals
• Scientific Controversy
• The Rock Cycle

[noun - atoms & subatomic particles, atoms & subatomic particles] A measure of an object's interaction with an external magnetic field. A magnet, an electron, and a planet all have magnetic moments. For particles, the magnetic moment is caused by the spin and charge of the object.

• Appears in modules:

• Atomic Theory III

Forces of attraction or repulsion between objects.

• Appears in modules:

• Chemical Bonding
• Energy
• Franklin Chang Díaz
• Light and Electromagnetism
• Origins of Plate Tectonic Theory

[noun - equations] Magnitude is a number assigned to a quantity and refers to the size or extent of something. There are several differing scientific uses of the term. In physics, it refers to the quantity of a measurement such as length, in astronomy it may refer to the brightness of a star, while in geology, it can indicate the strength of an earthquake.

• Appears in modules:

• Atomic Theory I
• Biodiversity I
• Data Analysis and Interpretation
• Experimentation in Scientific Research
• Introduction to Inferential Statistics
• Properties of Liquids
• Scientific Controversy
• Scientific Notation and Order of Magnitude
• Statistics in Science
• The Nature of Scientific Knowledge
• Uncertainty, Error, and Confidence
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - materials science, physical & chemical properties] The extent to which a solid can be hammered into a sheet without breaking. Metallic solids generally have high malleability.

• Appears in modules:

• Properties of Solids

[person - energy resources, human impacts on the environment, natural resources, ethics] English ordained minister and economist born in Dorking, Surrey (1766-1834). In 1798 he published his Essay on Population, suggesting that a given population will always exceed its food supply, and it would therefore be counterproductive to provide starving populations with food. Instead, he argued, social equality must be achieved through other means, such as universal suffrage and state-funded education for the poor.

• Appears in modules:

• Charles Darwin II

[noun - chemical reactions, atoms & subatomic particles, energy] A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during World War II.

• Appears in modules:

• Luis Walter Alvarez
• Ruth Benerito

[noun - research methods] The act of purposely controlling, changing, or adapting one aspect or condition in an experiment.

• Appears in modules:

• Experimentation in Scientific Research
• Exponential Equations in Science I

[noun - landforms & geologic formations, seismology & plate tectonics] The middle portion of the interior of the Earth, starting below the crust at 5-70 km below the Earth’s surface and continuing to a depth of 2900 km. The mantle is composed mainly of the rock peridotite.

• Appears in modules:

• Absorption, Distribution, and Storage of Chemicals
• Adaptation
• Atomic Theory II
• Chemical Bonding
• Composition of Earth's Atmosphere
• Data Analysis and Interpretation
• Defining Minerals
• Description in Scientific Research
• Discovery and Structure of Cells
• DNA I
• Earth Structure
• Ellen Ochoa
• Factors that Control Earth's Temperature
• Franklin Chang Díaz
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Kevin Arrigo
• Mario Molina
• Membranes I
• Modeling in Scientific Research
• Plates, Plate Boundaries, and Driving Forces
• Properties of Minerals
• Properties of Solids
• Scientific Controversy
• Scientists and the Scientific Community
• The Hydrologic Cycle
• The Nitrogen Cycle
• The Rock Cycle
• The Silicate Minerals
• Theories, Hypotheses, and Laws
• Using Graphs and Visual Data in Science
• Utilizing the Scientific Literature

[noun - science communication] An article or other document submitted or considered for publication.

• Appears in modules:

• Louis Tompkins Wright
• Peer Review in Scientific Publishing
• Scientific Ethics
• Scientists and the Scientific Community
• Understanding Scientific Journals and Articles
• Utilizing the Scientific Literature

[noun - atoms & subatomic particles, matter, physical & chemical properties, atoms & subatomic particles, matter] A fundamental property of matter which is a numerical measure of the inertia of an object or the amount of matter that an object contains. The mass of an object is different from its weight as mass is independent of the gravitational field exerted on an object.

• Appears in modules:

• Adaptation
• Atomic Theory I
• Atomic Theory II
• Carlos J. Finlay
• Cell Division I
• Chemical Equations
• Chemical Reactions
• Comparison in Scientific Research
• Composition of Earth's Atmosphere
• Confidence Intervals
• Defining Minerals
• Density
• Description in Scientific Research
• Diffusion I
• Early Ideas about Matter
• Factors that Control Regional Climate
• France Anne-Dominic Córdova
• Gravity
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Introduction to Inferential Statistics
• Kinetic-Molecular Theory
• Meselson and Stahl
• Nuclear Chemistry
• Peer Review in Scientific Publishing
• Photosynthesis I
• Properties of Minerals
• Properties of Solids
• Scientific Institutions and Societies
• The Metric System
• The Mole and Atomic Mass
• The Nature of Scientific Knowledge
• The Practice of Science
• The Rock Cycle
• Uncertainty, Error, and Confidence

[noun - scientific tools & techniques, energy, energy, atmospheric science, physical & chemical properties] A spectrometer that measures the composition of samples by analyzing the mass to charge ratio (m/z) of components in the sample. To do this, the sample introduced into the spectrometer is ionized under high energy, and the various ions are then separated in a magnetic field and measured. The specific m/z signature of each ion is then used to identify the parent element or compound.

• Appears in modules:

• Composition of Earth's Atmosphere
• Defining Minerals
• Franklin Chang Díaz
• History of Earth's Atmosphere I
• Properties of Minerals

[adjective - genetics & inheritance] Derived from or related to one's mother.

• Appears in modules:

• César Milstein
• Future of Human Evolution
• Mendel and Inheritance
• Population Genetics
• Y-Chromsome and Mitochondrial DNA Haplotypes

[verb - research methods] The process of analyzing and describing real-life situations using appropriate mathematics and statistics. Modeling is often used to express a situation as an equation and to use the equation to better understand the situation and make better future decisions about it.

• Appears in modules:

• Modeling in Scientific Research
• Uncertainty, Error, and Confidence

[noun] The substance that makes up physical objects.

• Appears in modules:

• Acids and Bases I
• Atomic Theory I
• Atomic Theory II
• Atomic Theory III
• Chemical Equations
• Composition of Earth's Atmosphere
• Density
• Diffusion I
• Discovery and Structure of Cells
• Early Ideas about Matter
• France Anne-Dominic Córdova
• Franklin Chang Díaz
• History of Earth's Atmosphere I
• Introduction to Descriptive Statistics
• Kinetic-Molecular Theory
• Light I
• Luis Walter Alvarez
• Origins of Life I
• Peer Review in Scientific Publishing
• Properties of Liquids
• Properties of Solids
• States of Matter
• Stoichiometry
• The Carbon Cycle
• The Mole and Atomic Mass
• The Nitrogen Cycle
• Theories, Hypotheses, and Laws
• Thermodynamics I

[person - oceanography, seismology & plate tectonics] English marine geophysicist, born in Porlock, Somerset (1931-1997). In 1962, Matthews participated in the International Indian Ocean Expedition and made a detailed survey of a submarine ridge that showed that the pattern of magnetic polarity of seafloor rocks surrounding the ridge was symmetric. This discovery contributed to the widespread acceptance of the plate tectonic theory. He also studied the structure and evolution of continental crust using deep crustal seismics.

• Appears in modules:

• Origins of Plate Tectonic Theory

[person - atmospheric science] (1806-1873) American naval officer and chronicler of winds, currents, and other observations. Maury led the effort to standardize meteorological observations so that they could be shared and compiled more easily. He is best known for his publication, The Physical Geography of the Sea and its Meteorology, first published in 1855.

• Appears in modules:

• Data Analysis and Interpretation

[noun - hydrology & fresh water, oceanography, bioregions, biomes & ecosystems, natural resources] In aquatic sciences, the deepest part of a specified area, such as a lake or gulf. Depth is an important factor in aquatic systems because it influences the water body’s overall temperature, water volume, and its ability to sustain plant and animal life. Shallow ponds, for example, will be warmer overall than deeper ponds in the same geographical region because they have a greater surface area/depth ratio, and so the available sunlight warms the water to a greater extent.

• Appears in modules:

• The Phosphorus Cycle

[person - energy, electromagnetism] Scottish theoretical physicist and mathematician born in Edinburgh (1831-1879). Maxwell developed the classical electromagnetic theory, which synthesized previously unrelated observations, experiments, and equations of electricity and magnetism. In 1864, Maxwell wrote A Dynamical Theory of the Electromagnetic Field, in which he proposed that light is a wave. He also described what is now known as Maxwellian distribution, a statistical way of describing the kinetic theory of gases.

• Appears in modules:

• Atomic Theory III
• Introduction to Descriptive Statistics
• Kinetic-Molecular Theory
• Light and Electromagnetism
• Light I

[noun - scientific tools & techniques] The abbreviation for millibar.

• Appears in modules:

• Composition of Earth's Atmosphere

[person - genetics & inheritance] (June 9, 1911 - January 2, 2005) An American physician and geneticist who specialized in infectious diseases. McCarty is remembered for discovering, with Oswald Avery and Colin MacLeod, that DNA is responsible for changes in form and function of bacteria. McCarty's later work focused on rheumatic fever and its relationship to the Streptococcus bacteria, and he pioneered the now-standard medical practice of using protein levels in blood to measure rheumatic inflammation.

• Appears in modules:

• DNA I

[noun - units of measurement, statistics] In statistics, mean commonly refers to the arithmetic mean, also called the average, which is one measure of the mid-point of a dataset. The mean and median approach one another in datasets that approach a normal distribution, but can differ substantially in datasets with skewed distributions. Compare to median. The mean is calculated by obtaining the sum of the values in a dataset and dividing that sum by the number of data points, as in the formulas shown.

• Appears in modules:

• Atomic Theory II
• Biodiversity I
• Chemical Equations
• Comparison in Scientific Research
• Composition of Earth's Atmosphere
• Confidence Intervals
• Data Analysis and Interpretation
• Fabiola León-Velarde
• Factors that Control Earth's Temperature
• Factors that Control Regional Climate
• Introduction to Descriptive Statistics
• Introduction to Inferential Statistics
• Introduction to Paleoanthropology
• Kinetic-Molecular Theory
• Linear Equations in Science
• Nuclear Chemistry
• Properties of Liquids
• The Carbon Cycle
• Uncertainty, Error, and Confidence

[noun - biomolecules, atoms & subatomic particles, matter, atoms & subatomic particles, matter] The average distance a particle moves between impacts with other particles.

[adjective - energy, mechanics] Involving physical force or motion.

• Appears in modules:

• Atomic Theory III
• Craig Lee
• Diffusion I
• Earth Structure
• Ellen Ochoa
• Energy
• Energy Metabolism II
• Franklin Chang Díaz
• Light and Electromagnetism
• Luis E. Miramontes
• Scientists and the Scientific Community
• The Phosphorus Cycle
• Thermodynamics I

[person - anatomy & physiology, medicine, research methods, scientific concepts] English biologist and essayist born in Brazil (1915-1987). Though he initially studied zoology, he became more interested in medicine in graduate school. With Sir Frank MacFarlane Burnet, Medawar won the Nobel Prize for Physiology or Medicine in 1960 "for discovery of acquired immunological tolerance"; Medawar's work concerned skin grafting and other organ transplants in humans. In his later years, he became a prolific author about the nature of science, and is well known for his essays "The Art of the Soluble" and "The Phenomenon of Man."

• Appears in modules:

• Creativity in Science

[noun - units of measurement, statistics] In statistics, the median is the value separating the upper half from the lower half of a dataset. In other words, it is the middle value of the data when they are arranged in order of magnitude. The median is a characteristic of a dataset comparable to the mean. The median and mean approach one another in datasets that approach the normal distribution, but can differ substantially in datasets with skewed distributions. Compare to mean.

• Appears in modules:

• Introduction to Descriptive Statistics

[noun - astrophysics, units of measurement] (Mpc) A numerical value of distance in space. 1 Mpc = 1 million paresecs, where one parsec equals 3.26 light years, or ~19 trillion miles.

[noun - cells, genetics & inheritance] Process, occurring in sexually reproducing eukaryotes, in which a single cell divides twice, yielding four cells, also called gametes, each of which is haploid (it contains half the genome of the organism). In males, gametes produced are called sperm, whereas gametes produced by females are called ova, or eggs.

• Appears in modules:

• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - organisms] The pigment responsible for darker skin tones.

[noun - materials science, matter, physical & chemical properties] The temperature at which a compound is transformed from its solid state to its liquid state, and where the solid and liquid states exist in equilibrium. During the transition from solid to liquid, the energy put into the system goes to changing the compound’s state, not increasing the temperature, so the temperature remains constant until the solid is completely melted.

• Appears in modules:

• Percy Lavon Julian
• Properties of Solids
• Temperature

[noun - cells] A thin layer of tissue that forms a boundary of a cell or cell part.

• Appears in modules:

• Blood Biology I
• Cell Division I
• Cellular Organelles I
• Diffusion I
• Discovery and Structure of Cells
• Energy Metabolism II
• Gene Expression
• Lipids
• Membranes I
• Membranes II
• Origins of Life I
• Origins of Life II
• Photosynthesis I
• Properties of Liquids
• Santiago Ramón y Cajal and Camillo Golgi
• The Phosphorus Cycle

[noun - biomolecules, cells] Proteins embedded in the plasma membrane of a cell that pump specific molecules or ions into or out of the cell.

[person - genetics & inheritance] Austrian Augustinian monk and scientist born in Heizendorf (now Hynice, Chech Republic) (1822-1884). In 1865, Mendel wrote Versuche über Pflanzen-Hybride (Treatises on Plant Hybrids), which detailed his observations on the inheritance of various traits in cross-bred pea plants and presented his principles of hereditary transmission. Unfortunately, the importance of his work was not recognized until after his death.

• Appears in modules:

• Barbara McClintock
• Creativity in Science
• DNA I
• Gene Expression
• Mendel and Independent Assortment
• Mendel and Inheritance
• Scientific Institutions and Societies
• Scientists and the Scientific Community
• Theories, Hypotheses, and Laws

[person - functional groups, physical & chemical properties] Russian inventor and chemist born in Tobolsk, Siberia (1834-1907). Mendeleev's most famous work is the development of the periodic table of elements, and his prediction of properties of elements that were, at that time, not yet discovered. In 1869, Mendeleev helped found the Russian Chemical Society. He researched in many fields, including physics, hydrodynamics, meteorology, and chemical technology.

• Appears in modules:

• Atomic Theory III
• The Periodic Table of Elements

[noun - atmospheric science, landforms & geologic formations] 1. The lowermost portion of the mantle. 2. The layer of the atmosphere above the stratosphere, where temperature decreases with altitude.

• Appears in modules:

• Composition of Earth's Atmosphere
• Earth Structure

[noun - anatomy & physiology, organisms, chemical reactions] A sequence of biochemical reactions in living organisms that converts food into energy used to drive other biological processes. Also, the sequence of transformations foreign compounds undergo inside a living cell.

• Appears in modules:

• Adaptation
• Cellular Organelles I
• Energy Metabolism I
• Experimentation in Scientific Research
• Gene Expression
• Meselson and Stahl
• The Carbon Cycle

[noun - atoms & subatomic particles, materials science, matter, physical & chemical properties] A bond between two metal atoms. Metallic bonds are strong and non-directional, meaning that it is hard to separate metal atoms but they can move and remain bonded as long as some parts of their surfaces are in contact. The outer electrons are relatively free to move between bonded metal atoms.

• Appears in modules:

• Properties of Solids

[adjective - physical & chemical properties, rocks & minerals] Formed through the processes involved in metamorphism, which include deep burial, exposure to high temperatures and pressures, and interactions with hydrothermal fluids. Metamorphic rocks are generally considered to have a parent rock, or protolith, which can be any rock type. The minerals and textures that are produced through metamorphism are indicative of both the protolith and the metamorphic environment.

• Appears in modules:

• The Rock Cycle
• The Silicate Minerals

[noun - landforms & geologic formations, physical & chemical properties, rocks & minerals] Physical and chemical changes to rocks that occur below the Earth's surface. These changes are caused by increased temperature, increased pressure, and the presence of hydrothermal fluids, and result in the growth and reorientation of crystals in the rock. Metamorphism does not include melting - once magma forms, the resulting rock will be igneous.

[noun - atmospheric science, weather & climate] The scientific study of the atmosphere including the processes that cause particular weather conditions.

• Appears in modules:

• Earth Structure
• Ellen Ochoa
• Factors that Control Regional Climate
• Modeling in Scientific Research
• Scientific Controversy
• The Process of Science

[noun - research methods] A procedure or process; a systematic way of performing a task or conducting research.

• Appears in modules:

• Animal Behavior
• Atomic Theory II
• Atomic Theory IV
• Bernardo Houssay
• Biodiversity I
• Bone Changes in Rock Climbers
• Carlos J. Finlay
• Cellular Organelles I
• Charles Darwin I
• Charles Darwin II
• Comparison in Scientific Research
• Confidence Intervals
• Craig Lee
• Creativity in Science
• Data Analysis and Interpretation
• David Ho
• Density
• Description in Scientific Research
• Energy Metabolism I
• Experimentation in Scientific Research
• Exponential Equations in Science I
• Future of Human Evolution
• Gene Expression
• Introduction to Inferential Statistics
• Kevin Arrigo
• Linear Equations in Science
• Luis Walter Alvarez
• Mario Molina
• Membranes I
• Meselson and Stahl
• Modeling in Scientific Research
• Origins of Life I
• Peer Review in Scientific Publishing
• Properties of Minerals
• Properties of Solids
• Ruth Benerito
• Santiago Ramón y Cajal and Camillo Golgi
• Scientific Controversy
• Scientific Ethics
• Scientific Institutions and Societies
• Scientific Notation and Order of Magnitude
• Statistics in Science
• Stoichiometry
• Temperature
• The Carbon Cycle
• The Case of the Ivory-billed Woodpecker
• The Nature of Scientific Knowledge
• The Phosphorus Cycle
• The Practice of Science
• The Process of Science
• The Scientific Method
• Uncertainty, Error, and Confidence
• Understanding Scientific Journals and Articles
• Unit Conversion
• Utilizing the Scientific Literature

[noun - research methods] A set of procedures or methods of inquiry used in a particular field of study.

• Appears in modules:

• Experimentation in Scientific Research
• Scientific Ethics
• The Piltdown Hoax
• The Practice of Science

[person - seismology & plate tectonics, light & optics] English natural philosopher and geologist, born in Nottinghamshire (1724-1793). In 1750 he published A Treatise of Artificial Magnets, detailing his observations on the variations in forces between magnetic poles. He also demonstrated radiation pressure, adding support to Christian Huygens' argument that light consists of waves.

• Appears in modules:

• Gravity

[person - stellar and galactic astronomy, light & optics] American physicist, born in Strelno, Prussia (1852-1931). He is remembered for his work in optics, particularly for his early, extremely accurate experiments to determine the velocity of light. Michelson invented the interferometer, which he used to determine the effect of Earth's motion on the observed velocity of light. He was also interested in astronomy, and, using his interferometer, accurately measured the diameter of the star Betelgeuse. He was awarded a Nobel Prize in physics in 1907.

• Appears in modules:

• Light and Electromagnetism

[adjective - organisms] Relating to microorganisms such as bacteria.

• Appears in modules:

• Origins of Life I
• The Nitrogen Cycle

[noun] A fossil so small that it must be studied by using a microscope.

• Appears in modules:

• History of Earth's Atmosphere II

[noun - biomolecules, nutrition, rocks & minerals, energy resources, natural resources, nutrient cycles] Nutrients that are needed to grow and reproduce, but in small amounts. For example, plants need boron in order to develop fruits and seeds. However, the amount of boron needed to perform this function is much less than the amount of nitrogen the plant needs to perform photosynthesis. In humans, supplements generally labeled as vitamins fall into the micronutrient category. See also: limiting nutrient and macronutrient.

[noun - oceanography] extremely small pieces of plastic debris in the environment, due to the disposal and breakdown of consumer products

[adjective - anatomy & physiology, matter, physical & chemical properties, units of measurement] That which cannot be seen with the unaided eye and requires a tool (such as a microscope) to view. Many scientific disciplines explore both large-scale (macroscopic) and tiny (microscopic) properties to fully understand phenomena and organisms. Contrast with macroscopic .

• Appears in modules:

• Bernardo Houssay
• Discovery and Structure of Cells
• Energy Metabolism I
• Factors that Control Earth's Temperature
• Kinetic-Molecular Theory
• Properties of Solids
• Santiago Ramón y Cajal and Camillo Golgi
• Scientific Notation and Order of Magnitude

[noun - anatomy & physiology, cells] Microtubules are hollow cylinders of tubulin protein in the cytoplasm of all eukaryotic cells. As part of a cell's cytoskeleton, they shape and support it. Microtubules are also involved in the transport of materials inside of the cell. They serve as paths along which organelles with motor-equipped molecules can move. Microtubules participate in the separation of chromosomes during cell division (mitosis) and can act alone or form such complex structures as flagella and cilia.

• Appears in modules:

• Cell Division II

[noun - landforms & geologic formations, oceanography] A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges are often referred to by their more specific names: Mid-Atlantic Ridge, East Pacific Rise, etc.

• Appears in modules:

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

[noun - time periods] European history from the 5th century to the 15th century. The Middle Ages follow the fall of the Western Roman Empire in 476 and are marked by depopulation, migration from urban centers, and increasing frequency of barbarian invasions. Key events include the Crusades, during which Europeans attempted to recapture the Holy Land, and the development of the serf system, which enabled systematic agriculture to begin again. Agriculture was widely affected due to climate change, resulting in frequent famines. In addition, the Black Death (which may have been the bubonic plague) spread rapidly across Europe, killing 30-60% of the population by the mid-14th century. With the resulting decrease in the labor force, due to death by disease or hunger, landlords were forced to offer higher wages to entice peasants to work in their fields. The end of the Middle Ages is generally considered to be 1453, the date of the Turks' conquest of Constantinople.

• Appears in modules:

• Charles Darwin I
• Chemical Reactions
• Energy
• Properties of Minerals

[person - genetics & inheritance] A Swiss physician and biologist (1844 - 1895). An attack of typhoid fever left him partially deaf, and he felt this would be a disadvantage as a doctor, so he decided to pursue physiological chemistry instead. He is remembered for isolating nucleic acids from white blood cells, one of many steps that made possible the discovery that DNA carries genetic material. In addition, Meischer proved that breathing is regulated by carbon dioxide concentrations in the blood.

• Appears in modules:

• DNA II

[noun - atmospheric science] A unit of measurement of atmospheric pressure equivalent to 1 gram per square centimeter. Average sea level pressure is 1013 mb, equivalent to one Atmosphere.

• Appears in modules:

• Composition of Earth's Atmosphere

[noun - rocks & minerals] A naturally formed, inorganic solid with a specific chemical composition and characteristic crystal structure. Examples of minerals include quartz (SiO₂), salt (also called halite, NaCl), and graphite (C). Rocks are formed of one or more minerals.

• Appears in modules:

• Biodiversity I
• César Milstein
• Charles Darwin I
• Chemical Reactions
• Craig Lee
• Defining Minerals
• Description in Scientific Research
• Early Ideas about Matter
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Origins of Plate Tectonic Theory
• Properties of Minerals
• Scientific Controversy
• States of Matter
• Statistics in Science
• Stoichiometry
• The Carbon Cycle
• The Phosphorus Cycle
• The Rock Cycle
• The Silicate Minerals

[verb - physical & chemical properties, rocks & minerals] Conversion into an inorganic form.

• Appears in modules:

• The Nitrogen Cycle

[adjective - physical & chemical properties, hydrology & fresh water] Two substances that can mix completely, such as two liquids combining to form a homogeneous solution.

• Appears in modules:

• Solutions, Solubility, and Colligative Properties

[noun - ethics] Deliberate bad behavior; activity that is morally or legally wrong.

• Appears in modules:

• Peer Review in Scientific Publishing
• Scientific Ethics

[noun - anatomy & physiology, cells] Organelles that convert energy from food molecules into ATP, the main energy currency inside cells.

• Appears in modules:

• Cellular Organelles I
• Discovery and Structure of Cells
• Energy Metabolism II
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - cells, genetics & inheritance] Process occurring as part of the eukaryotic cell cycle. In mitosis, chromosomes in the cell nucleus separate into two identical chromosome sets, the two sets are separated, and two independent nuclei form, each with its own set of chromosomes matching that of the parent nucleus. Mitosis consists of five stages: prophase, prometaphase, metaphase, anaphase, and telophase.

• Appears in modules:

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

[noun - physical & chemical properties] two or more pure substances combined that retain their unique properties. Mixtures include homogeneous mixtures, also called or solutions, where one can not distinguish the different parts, and heterogeneous mixtures, in which you can distinguish the different parts. Mixtures are physically combined and can be physically separated. For example, rainwater is a homogeneous mixture as the particles of gas dissolved in them are evenly distributed and cannot be seen. River water is commonly a heterogeneous mixture where you can see soil particles or sediments floating in the water.

[noun - data, research methods] A representation, pattern, or mathematical description that can help scientists replicate a system.

• Appears in modules:

• Animal Behavior
• Atomic Theory I
• Atomic Theory II
• Atomic Theory III
• Atomic Theory IV
• Bernardo Houssay
• Cell Division II
• Charles Darwin I
• Charles Darwin III
• Chemical Bonding
• Craig Lee
• Creativity in Science
• Data Analysis and Interpretation
• Description in Scientific Research
• Diffusion I
• DNA II
• DNA III
• Exponential Equations in Science I
• Factors that Control Earth's Temperature
• Factors that Control Regional Climate
• France Anne-Dominic Córdova
• Franklin Chang Díaz
• Gravity
• Introduction to Paleoanthropology
• Light and Electromagnetism
• Light I
• Mario Molina
• Membranes I
• Mendel and Independent Assortment
• Meselson and Stahl
• Modeling in Scientific Research
• Origins of Life I
• Scientific Controversy
• Scientists and the Scientific Community
• Sergio Avila
• The How and Why of Scientific Meetings
• The Nature of Scientific Knowledge
• The Practice of Science
• Theories, Hypotheses, and Laws
• Uncertainty, Error, and Confidence
• Understanding Scientific Journals and Articles

[noun - seismology & plate tectonics] The commonly used abbreviation of the Mohorovicic Discontinuity, the boundary between the crust and the mantle.

• Appears in modules:

• Discovery and Structure of Cells
• Earth Structure

[person - landforms & geologic formations, seismology & plate tectonics] Croatian meteorologist and geophysicst born in Volosko (1857-1921). In 1901, Mohorovičić was appointed head on the meteorological service of Croatia and Slavonia. He upgraded the services to European standards, and expanded the work of the observatory into seismology, geomagnetism, and gravitation. Mohorovičić discovered the existence of S and P seismic waves, which propagate through the Earth at different velocities. From seismic refractions, Mohorovičić discovered a discontinuity between the less dense rocks of the crust and denser rocks of the mantle, now called the Mohorovičić discontinuity (known more commonly as the Moho).

[noun - landforms & geologic formations, seismology & plate tectonics] The boundary within the Earth between the crust and the mantle, as indicated by the refraction and velocity change of seismic waves recognized by Andrija Mohorovičić. The depth of the Mohorovicic Discontinuity is ~5-7 km below oceanic crust and ~10-70 km below continental crust.

[person - rocks & minerals] German geologist and mineralogist born in Gernrode (1773-1839). In 1802, after studying at the Mining Academy in Freiberg, Saxony, Mohs moved Austria, where he was hired to identify minerals in a private collection. In order to do this, he classified the minerals by their physical characteristics rather than their chemical compositions (as was usually done). He developed the Mohs' hardness ^~scale, a relative ^~scale of the hardness of minerals that remains a useful way to identify minerals in the field.

• Appears in modules:

• Properties of Minerals

[noun - atoms & subatomic particles, units of measurement] An amount equal to Avogadro's number, or 6.02 × 10²³. One mole of atoms is equal to 6.02 × 10²³ atoms.

• Appears in modules:

• Acids and Bases I
• Chemical Equations
• Diffusion I
• Properties of Gases
• Solutions, Solubility, and Colligative Properties
• Stoichiometry
• The Mole and Atomic Mass

[chemical reactions] The proportional relationship (ratio) between any two compounds involved in a chemical reaction.

• Appears in modules:

• Stoichiometry

[noun - atoms & subatomic particles, units of measurement] The formula weight of a compound, given by summing the atomic weights of atoms in the compound. Given in grams, the molecular weight is the weight of one mole of molecules in a compound.

• Appears in modules:

• Diffusion I
• The Mole and Atomic Mass

[noun - atoms & subatomic particles, compounds, organic & biochemistry] A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a chemical compound that retains the chemical properties of the compound.

• Appears in modules:

• Absorption, Distribution, and Storage of Chemicals
• Atomic Theory I
• Biodiversity I
• Carbohydrates
• Carbon Chemistry
• Cell Division II
• Cellular Organelles I
• César Milstein
• Chemical Bonding
• Chemical Equations
• Chemical Reactions
• Composition of Earth's Atmosphere
• Creativity in Science
• Defining Minerals
• Density
• Description in Scientific Research
• Diffusion I
• Discovery and Structure of Cells
• DNA I
• DNA II
• DNA III
• Early Ideas about Matter
• Energy
• Energy Metabolism I
• Fats and Proteins
• Gene Expression
• History of Earth's Atmosphere I
• History of Earth's Atmosphere II
• Introduction to Descriptive Statistics
• Kinetic-Molecular Theory
• Luis E. Miramontes
• Mario Molina
• Membranes I
• Membranes II
• Meselson and Stahl
• Modeling in Scientific Research
• Nuclear Chemistry
• Percy Lavon Julian
• Photosynthesis I
• Properties of Gases
• Properties of Liquids
• Properties of Solids
• Scientists and the Scientific Community
• States of Matter
• The Carbon Cycle
• The Metric System
• The Mole and Atomic Mass
• The Nitrogen Cycle
• Thermodynamics I

[noun - atoms & subatomic particles, compounds, organic & biochemistry, physical & chemical properties] Any molecule that may become chemically bonded to other molecules of the same type to form a larger molecule called a polymer.

[person - matter, physical & chemical properties, matter, thermodynamics] A wealthy French balloonist, born in Annonay, France (1745 – 1799). Montgolfier and his brother Joseph-Michel designed and conducted the first successful flights in hot-air balloons.

[person - matter, physical & chemical properties, matter, thermodynamics] A wealthy French balloonist, born in Annonay, France (1740 – 1810). Montgolfier and his brother Jacques-Étienne designed and conducted the first successful flights in hot-air balloons.

[person - genetics & inheritance] (September 25, 1866 - December 4, 1945) An American embryologist who won the Nobel Prize in Physiology or Medicine in 1933 for his discoveries about the role that chromosomes play in heredity. Morgan's most important book, The Mechanism of Mendelian Heredity, with several coauthors, was published in 1915 and became a fundamental work in the field of genetics. Morgan's later work focused on embryology and on encouraging the use of genetics research and a mechanistic approach in all fields of biology.

• Appears in modules:

• Mendel and Inheritance

[noun] An organism that has undergone a change in genetic material.

• Appears in modules:

• César Milstein
• Gene Expression

[verb - genetics & inheritance] To undergo a change in genetic material.

[noun - genetics & inheritance] A change in gene sequences of cell DNA.

• Appears in modules:

• Barbara McClintock
• Cellular Organelles I
• César Milstein
• David Ho
• Future of Human Evolution
• Population Genetics
• Theories, Hypotheses, and Laws
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun] A story, idea, or concept invented with a purpose. Myths are generally intended to explain the relationship between gods or natural forces and humans. The events in myths are often impossible, but myths contain important social or religious information for the population that has created them.

• Appears in modules:

• Charles Darwin I
• Description in Scientific Research