scienceterms Flashcards
(136 cards)
2
Q
Scientific Method
A
A systematic process of learning that includes observations, stating the problem, hypothesizing, experimentation, gathering and analyzing data, and stating a conclusion.
3
Q
Compression Wave
A
Waves in which the disturbance takes place in the direction of propagation.
4
Q
Conduction
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The transfer of energy that occurs when a body of high temperature transfers its heat through a connecting medium to one of lower temperature.
5
Q
Convection
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The process by which large amounts of energy are transferred through the movement of gas and liquid.
6
Q
First Harmonic
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Also known as the fundamental frequency; has two nodes at each end and one antinode in the middle, forming a single hill or trough.
7
Q
Focal Length
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The distance between the pole of a lens or mirror to the principal focus and is always equal to half of the radius of curvature of lens or mirror. f = R/2.
8
Q
Harmonic Oscillator
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Any object that oscillates about a stable equilibrium position and experiences a restoring force approximately described by Hooke’s law.
9
Q
Kinetic Energy
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In physics, the energy of an object in motion.
10
Q
Kinetic Friction
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Occurs when one object is moving with respect to the surface with which it is in contact. It has magnitude given by FK = uKN. (uK is the coefficient of kinetic friction and N is the magnitude of the Normal Force).
11
Q
Newton’s First Law of Motion
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A fundamental principle in physics which states that an object at rest will remain at rest and an object in motion will stay in motion, moving at the same velocity, unless an unbalanced force is applied to it.
12
Q
Newton’s Second Law of Motion
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A fundamental principle in physics which states that unbalanced forces acting on an object will produce a reaction, or acceleration, that is directly proportional to the amount of the force applied, and inversely proportional to the object’s mass.
13
Q
Newton’s Third Law of Motion
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A fundamental principle in physics which states that every action will create a reverse, or opposite, but equal reaction.
14
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Normal Force
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The force one surface exerts on another surface. It is perpendicular to the surface of contact.
15
Q
Photovoltaic Cell
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A specialized semiconductor diode that converts visible light into direct current.
16
Q
Potential Energy
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The capacity a resting object has to do work from a particular position; stored energy.
17
Q
Radiation
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The transfer of energy through waves and particles; emission and propagation of energy in the form of rays or waves without the requirement of a connective medium.
18
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Refraction
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The behavior of a single frequency wave traveling through a medium or field that comes into contact with an object and is bent before passing into a second medium.
19
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Resultant Vector
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The sum of two or more vectors.
20
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Second Harmonic
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A sine wave having two times the frequency of the fundamental wave.
21
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Static Friction
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Occurs when an object is in contact with the surface it is resting on. It has a magnitude given by Fs = usN (us is the coefficient of static friction, N is the magnitude of the Normal Force).
22
Q
Third Harmonic
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A sine wave having three times the frequency of the fundamental wave.
23
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Transverse Wave
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A wave that moves in a direction perpendicular to that of its medium.
24
Q
Wave Amplitude
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The magnitude of the greatest departure from equilibrium of the wave disturbance.
25
Q
Wave Frequency
A
A wave characteristic referring to the number of cycles occurring per second.
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Wavelength
The distance (measured in the direction of propagation) between two points in the same phase in consecutive cycles of a wave.
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Alpha Decay
The radioactive decay of an atomic nucleus accompanied by emission of an alpha particle.
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Atomic Mass
The mass of an atom expressed in atomic mass units (amu).
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Atomic Number
The number of protons in the nucleus of an atom.
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Barometer
An instrument for measuring atmospheric pressure, used especially in weather forecasting.
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Beta Decay
The radioactive decay of an atomic nucleus accompanied by emission of a beta particle.
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Calorimetry
Measurement of the amount of heat evolved or absorbed in chemical reaction, change of state, or formation of a solution.
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Conservation of Energy
A fundamental thermodynamics principle which states that energy cannot be created or destroyed, although it can be changed from one form to another.
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Conservation of Mass
A fundamental thermodynamics principle which states that reactions and interactions which change the properties of substances leave their total masses unchanged.
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Equilibrium Constant
A constant, characteristic for each chemical reaction; relates the specific concentrations of all reactants and products at equilibrium at a given temperature and pressure.
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Gamma Decay
A radioactive process in which an atomic nucleus loses energy by emitting a gamma ray without a change in its atomic or mass numbers.
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Gibb’s Energy
A mathematical expression, developed in the 1870s by the American mathematical physicist Willard Gibbs, defined as the energy portion of a thermodynamic system available to do work.
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Heat Capacity
The amount of heat required to raise the temperature of one mole or one gram of a substance by one degree Celsius without change of phase.
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Heat of Combustion
The amount of heat released per unit mass or unit volume of a substance when the substance is completely burned.
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Heat of Formation
The increase in enthalpy resulting from the formation of 1 mole of a substance from its elements at constant pressure.
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Intermolecular Forces
Electromagnetic forces which act between molecules or between widely separated regions of a macromolecule. Listed in order of decreasing strength, these forces are: ionic interactions, hydrogen bonds, dipole-dipole interactions, London dispersion forces (Van der Waals forces).
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Intramolecular Bonds
Forces which keep atoms held together in molecules and in solids, such as covalent, ionic, and aromatic bonds.
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Ionic Bond
A chemical bond between two ions with opposite charges, characterized by the unequal sharing of electrons.
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Ionization Constant
Analog of the dissociation constant, where k = [H+][A-]/[HA]; used for the application of the law of mass action to ionization; in the equation HA represents the acid, such as acetic acid.
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Manometer
A pressure gauge for comparing pressures of a gas.
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Molarity
The molar concentration of a solution, usually expressed as the number of moles of solute per liter of solution.
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Specific Heat
The amount of heat, measured in calories, required to raise the temperature of one gram of a substance by one Celsius degree. Also known as heat capacity.
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Spontaneous Process
A chemical reaction in which a system releases free energy (most often as heat) and moves to a lower, more thermodynamically stable, energy state. The sign convention of changes in free energy follows the general convention for thermodynamic measurements, in which a release of free energy from the system corresponds to a negative change in free energy, but a positive change for the surroundings.
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Adenosine Triphosphate (ATP)
A chemical compound nucleotide found in all living organisms that releases energy for cellular reactions when it converts to ADP.
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Bacteriophage
A virus that infects bacteria and may integrate into the genetic material of its host cell.
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Cellular Respiration
The series of metabolic processes by which living cells produce energy through the oxidation of organic substances.
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Eukaryote
Any organism with one or more cells that have visible nuclei and organelles. The group contains all living and fossil cellular organisms except bacteria and cyanobacteria.
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Hydrophilic
Having a strong affinity for water; tending to dissolve in, mix with, or be wetted by water.
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Hydrophobic
Not dissolving in, absorbing, or mixing easily with water.
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Lipid Bi-layer
A double layer of regularly arranged phospholipid molecules that is widely accepted as forming the basic structure of cell membranes and other biological membranes.
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Mitochondrial Membrane
The membrane surrounding the mitochondrion, containing proteins having ATP synthase, which make ATP in the mitochondrial matrix.
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Prokaryote
A unicellular organism having cells lacking membrane-bound nuclei; bacteria are the prime example but also included are blue-green algae and actinomycetes and mycoplasma.
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Protein Coat
The outer covering of protein surrounding the nucleic acid of a virus, also called the capsid.
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Allele
One of the variant forms of a gene at a particular locus, or location, on a chromosome. Different alleles produce variation in inherited characteristics such as hair color or blood type. In an individual, one form of the allele (the dominant one) may be expressed more than another form (the recessive one).
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Convergent Evolution
Describes the process whereby organisms not closely related independently acquire similar characteristics while evolving in separate and sometimes varying ecosystems.
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Deoxyribose Nucleic Acid (DNA)
The chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms. All known cellular life and some viruses have DNA. DNA is a long polymer of nucleotides (a polynucleotide) that encodes the sequence of amino acid residues in proteins, using the genetic code: each amino acid is represented by three consecutive nucleotides (a triplet code).
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Diploid Cell
A cell that contains both sets of homologous chromosomes.
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DNA Replication (DNA synthesis)
The process of copying the double-stranded DNA prior to cell division.
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Frameshift Mutation
A genetic mutation that inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence. Due to the triplet nature of gene expression by codons, the insertion or deletion can disrupt the reading frame, or the grouping of the codons, resulting in a completely different translation from the original. Frameshift mutations frequently result in severe genetic diseases.
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Genotype
The genetic identity of an individual that does not show as outward characteristics.
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Geographical Isolation
Describes a process by which a population of a species becomes geographically isolated from the remainder, and over time evolves characteristics different from the parent population (due to natural selection).
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Gradualism
A slow, steady change in a particular line of decent, rather than rapid change over a relatively short period of time.
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Haploid Cell
A cell that contains only a single set of chromosomes and therefore only a single set of genes.
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Meiosis
Cell division that produces reproductive cells in sexually reproducing organisms; the nucleus divides into four nuclei each containing half the chromosome number.
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Messenger RNA (mRNA)
Template for protein synthesis. Each set of three bases, called codons, specifies a certain protein in the sequence of amino acids that comprise the protein. The sequence of a strand of mRNA is based on the sequence of a complementary strand of DNA.
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Mitochondrial DNA
A small circular DNA molecule found in the mitochondria of a cell. Mitochondrial DNA is inherited only from the mother.
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Mitosis
The process by which a cell separates its duplicated genome into two identical halves. It is generally followed immediately by cytokinesis which divides the cytoplasm and cell membrane.
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Phenotype
The observable traits or characteristics of an organism, for example hair color, weight, or the presence or absence of a disease.
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Phylogenetic Tree
A tree showing the evolutionary interrelationships among various species or other entities that are believed to have a common ancestor. In a phylogenetic tree, each node with descendants represents the most recent common ancestor of the descendants, and edge lengths correspond to time estimates.
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Punctuated Equilibrium
Describes an evolutionary pattern marked by long stable periods that are interrupted by rapid changes, and involving many lines of descent.
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Ribonucleic acid (RNA)
A chemical similar to a single strand of DNA. In RNA, the letter U, which stands for uracil, is substituted for T in the genetic code. RNA delivers DNA's genetic message to the cytoplasm of a cell where proteins are made.
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Speciation
A process whereby over time one species evolves into a different species (anagenesis) or whereby one species diverges to become two or more species (cladogenesis).
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Transfer RNA (tRNA)
Small RNA molecules that carry amino acids to the ribosome for polymerization into a polypeptide. During translation the amino acid is inserted into the growing polypeptide chain when the anticodon of the tRNA pairs with a codon on the mRNA being translated.
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Active Immunity
An organisms resistance to disease or infection, developed because the organisms immune system has produced antibodies after an infection or inoculation.
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Bilateral Symmetry
The characteristic, in animals, of being symmetric about a plane running from head to tail.
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Cephalization
In humans the concentration of nervous tissues at one end of the human embryo to produce the brain and head is called cephalization.
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Cretaceous Period
From 135 million to 63 million years ago marked by the end of the age of reptiles and the appearance of modern insects and flowering plants.
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Faunal Succession Theory
Holds that different strata contain particular types of fossilized flora and fauna, and that these fossil forms succeed each other in a specific and predictable order that can be identified over wide distances. This allows for any period of time in the history of the Earth to be identified by the fossils found in a particular stratum.
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Fixed Action Pattern (FAP)
An inborn sequence of behavior in which variations do not normally occur.
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Homeostasis
The ability of a living organism to adjust its internal environment to maintain a stable equilibrium; such as the ability of warm-blooded animals to maintain a constant temperature.
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Lysogenic Infection
An infective process characterized by the incorporation of the DNA of the infecting phage into the host cell chromosome. Once incorporated, the phage DNA replicates along with the host DNA. The incorporated phage DNA is relatively inactive, thus permitting the host cell to continue fairly normal life processes.
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Lytic Infection
The normal cycle of infection of a cell by a virus or bacteriophage, in which mature virus or phage particles are produced and the cell is then lysed.
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Non-specific Defense Mechanism
Immune system defenses that do not differentiate between different pathogens, but act as barriers to pathogens. Examples include the skin, mucus, sweat, and tears.
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Ossification
The process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. It is thought that this process led to bone as a structural element in vertebrates.
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Passive Immunity
Immunity acquired by the transfer of antibodies from another organism. Passive transfer of antibody from mother to offspring is important for immune defense during the perinatal period.
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Peristalsis
The rhythmic, wave-like contraction of the digestive track that forces food through it.
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Specific defense mechanism
An immune response to an antigen in which specific antibodies are created or employed to attack and destroy the antigen.
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Vasoconstriction
The constriction of the capillaries in the skin in response to cold temperatures.
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Vasodilation
The opening up of the capillaries of the skin in response to warm temperatures, thus increasing the flow of blood to the surface of the body.
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Autotroph
An organism that produces organic compounds from carbon dioxide as a carbon source, using either light or reactions of inorganic chemical compounds, as a source of energy. An autotroph is known as a producer in a food chain.
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Biome
The world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment.
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Commensalism
The association between two organisms of different species in which one derives some benefit while the other is unaffected.
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Consumers
Any organism which must consume other organisms (living or dead) to satisfy its energy needs. Opposite of autotroph.
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Decomposers
Organisms (often fungi or bacteria) that break down organic materials to gain nutrients and energy.
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Density-dependent Limiting Factor
A limiting factor is one that controls a species population size or distribution. A density-dependent limiting factor is dependent on population density (example: the availability of food limiting the size of a local deer population).
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Density-independent Limiting Factor
A limiting factor is one that controls a species population size or distribution. A density-independent limiting factor is independent of population size or density(example: a forest fire destroys a local deer population).
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Heterotroph
An organism which requires an external supply of energy in the form of food as it cannot synthesize its own. A heterotroph is known as a consumer in the food chain.
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Mutualism
Any interaction between two species that benefits both; typically involves the exchange of substances or services.
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Parasitism
Interaction between two organisms, in which one organism (the parasite) benefits and the other (the host) is harmed.
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Producers
Any organism which brings energy into an ecosystem from inorganic sources. Most plants and many protists are producers.
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Symbiotic Relationships
Used to describe organisms (especially of different species) living together but not necessarily in a relationship beneficial to each other.
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Trophic Level
The position that an organism occupies in the energy pyramid or in the food chain. The trophic level describes what an organism consumes, as well as what consumes the organism.
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Deposition
Also known as sedimentation, is the geological process whereby material is added to a landform. This is the process by which wind, water or ice create a sediment deposit, through the laying down of granular material that has been eroded and transported from another geographical location.
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Erosion
The displacement of solids (soil, mud, rock and other particles) by the agents of wind, water or ice, by downward or down-slope movement in response to gravity or by living organisms (in the case of bioerosion). Erosion is distinguished from weathering, which is the decomposition of rock and particles through processes where no movement is involved, although the two processes may be concurrent.
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Evaporation
The process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. It is the opposite process of condensation.
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Fossil Fuels
Hydrocarbons formed from the remains of dead plants and animals. A general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.
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Hydrosphere
Describes the collective mass of water found on, under, and over the surface of a planet.
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Igneous Rock
Formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.
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Metamorphic Rock
The result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat (greater than 150 degrees Celsius) and extreme pressure causing profound physical and/or chemical change. The protolith may be sedimentary rock, igneous rock or another older metamorphic rock.
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Moh’s Hardness Scale
Characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created, in 1812, by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science.
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Plate Tectonics
The branch of geology studying the folding and faulting of the earth's crust.
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Rock Cycle
A fundamental concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.
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Transpiration
The evaporation of water from aerial parts of plants, especially leaves but also stems, flowers and fruits. Transpiration is a side effect of the plant needing to open its stomata in order to obtain carbon dioxide gas from the air for photosynthesis. Transpiration also cools plants and enables mass flow of mineral nutrients from roots to shoots.
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Water Cycle (hydrological cycle)
The cycle in which water evaporates from the oceans and the land surface, is carried over the earth in atmospheric circulation as water vapor, precipitates again as rain or snow, is intercepted by trees and vegetation, provides runoff on the land surface, infiltrates into soils, recharges groundwater, discharges into streams, and ultimately, flows out into the oceans, from which it will eventually evaporate again.
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Weathering
The process of disintegration of rocks, soils and their minerals through direct, or indirect contact with the atmosphere. Weathering occurs 'in situ', or 'without movement', and thus should not to be confused with erosion, which involves the movement and disintegration of rocks and minerals by processes such as water, wind, ice or gravity.
121
Black Hole
A region of space-time which cannot be seen by distant observers because light is trapped by a strong gravitational field.
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Coma
The spherical region of diffuse gas, about 150,000 km in diameter, which surrounds the nucleus of a comet. Together, the coma and the nucleus form the comet's head.
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Comet
A diffuse body of gas and solid particles (such as CN, C2, NH3, and OH), which orbits the Sun. The orbit is usually highly elliptical or even parabolic.
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Fall Equinox
The time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length all over the earth and occurring about September 22.
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Lunar Phase
Any of the aspects or appearances presented by the Moon as seen from Earth, determined by the portion of the Moon that is visibly illuminated by the Sun.
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Nuclear Fusion
The combining of the nuclei of small atoms to form the nuclei of larger ones, with a resulting release of large quantities of energy; the process that makes the sun shine, and hydrogen bomb explode.
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Primary Phases
A term used to categorize phases consisting of the new moon, first quarter moon, full moon, and last quarter.
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Pulsar
An object discovered at Cambridge University in 1967 which has the mass of a star and a radius no larger than that of Earth and which emits radio pulses with a very high degree of regularity.
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Spring Equinox
The time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length all over the earth and occurring about March 21.
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Summer Solstice
The moment when the Earth is in that point of its orbit where the northern or southern hemisphere is most inclined toward the sun.
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Winter Solstice
The moment when the Earth is in that point of its orbit where the northern or southern hemisphere is most inclined away from the sun.
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Accuracy
The correctness of a single measurement, assessed by comparing the measurement with the true or accepted value, based on evidence independent of the measurement.
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Database Software
A systematically arranged collection of computer data, structured so that it can be automatically retrieved or manipulated.
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Density
A measure of the amount of matter contained by a given volume.
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Precision
Describes the degree of reproducibility of a measurement.
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Spreadsheet Software
A computer program that displays numerical data in cells in a simulated accountant's worksheet of rows and columns in which hidden formulas can perform calculations on the visible data. Changing the contents of one cell can cause automatic recalculation of other cells.
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Word Processing Software
An application that provides the user with tools needed to write and edit and format text and to send it to a printer.
