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223 Cards in this Set

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machine a device that helps do work by either overcoming a force or changing the direction of the applied force
macromolecule a very large organic molecule, usually a polymer, composed of hundreds or thousands of atoms
macronucleus in many protozoans, the larger of the two types of cell nuclei
macronutrient an element required in relatively large amounts
macrophage an immune system cell that engulfs pathogens and other materials
madreporite the porous structure through which water enters and exits the water-vascular system of echinoderms
maficdescribes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
magic numbers the numbers 2, 8, 20, 28, 50, 82, and 126 that represent the number of particles in an extrastable atomic nucleus that has completed shells of protons and neutrons
magic numbers
magma liquid rock produced under the Earth's surface; igneous rocks are made of magma
magma chamberthe body of molten rock that feeds a volcano
magma chamber
magnet any material that attracts iron or materials containing iron
magma chamber
magnetic declination the difference between the magnetic north and the true north
magnetic declination
magnetic domaina region composed of a group of atoms whose magnetic fields are aligned in the same direction
magnetic domain
magnetic field a region where a magnetic force can be detected
magnetic field
magnetic forcethe force of attraction or repulsion generated by moving or spinning electric charges
magnetic force
magnetic pole one of two points, such as the ends of a magnet, that have opposing magnetic qualities
magnetic pole
magnetic quantum number the quantum number that corresponds to the alignment of the angular momentum component with a magnetic field
magnetic quantum number
magnetosphere a region of the space surrounding a planet where charged particles are controlled by the planet's magnetic field
magnification the increase of an object's apparent size by using lenses or mirrors
magnitude a measure of the strength of an earthquake
magnitudean element in the s-block or p-block of the periodic table
main sequence the location on the H-R diagram where most stars lie; it has a diagonal pattern from the lower right (low temperature and luminosity) to the upper left (high temperature and luminosity)
main sequence
malaria an infectious tropical disease caused by a protozoan and transmitted to humans by a mosquito; it produces high fevers, chills, sweating, and anemia
malignant tumor a cancerous mass of cells
malignant tumor
malleability the ability of a substance to be hammered or beaten into a sheet
malnutrition a disorder of nutrition that results when a person does not consume enough of each of the nutrients that are needed by the human body
Malpighian tubule an excretory tube that opens into the back part of the intestine of most insects and certain arthropods
Malpighian tubule
mammary gland a gland that is located in the chest of a female mammal and that secretes milk
mammary gland
mandible a type of mouthpart found in some arthropods and used to pierce and suck food; the lower part of the jaw
mangrove swamp a tropical or subtropical marine swamp that is characterized by the abundance of low to tall trees, especially mangrove trees
mangrove swamp
mantle in biology, a layer of tissue that covers the body of many invertebrates
mantle in Earth science, the layer of rock between Earth's crust and core
mantle cavity the space between the mantle and body mass in mollusks and brachiopods
mantle cavity
map a representation of the Earth’s surface
map projection a flat map that represents a spherical surface
map projection
marea large, dark area of basalt on the moon (plural, maria)
maria large, dark areas of basalt on the moon (singular, mare)
marine describes an ecosystem in the sea
an ecosystem in the sea
marine ecosystem
maritime polar a cold air mass that has high humidity as a result of passing over warmer water
maritime polar
maritime tropical a warm and humid air mass that typically forms over tropical oceans
maritime tropical
marsh a treeless wetland ecosystem where plants such as grasses grow
marsupial a mammal that does not have a placenta and that carries and nourishes its young in a pouch
mass defect the difference between the mass of an atom and the sum of the masses of the atom's protons, neutrons, and electrons
mass defect
mass density the concentration of matter of an object, measured as the mass per unit volume of a substance
mass density
mass extinction an episode during which large numbers of species become extinct
mass extinction
mass movement the movement of a large mass of sediment or a section of land down a slope
mass movement
mass number
mastax the muscular pharynx in rotifers
mathematical model one or more equations that represent the way a system or process works
mathematical model
matter anything that has mass and takes up space
maxilla a type of mouthpart found in most arthropods and located behind the mandible
maxillaped a thoracic appendage in arthropods that is used to manipulate food and to detect touch and chemicals
meander one of the bends, twists, or curves in a low-gradient stream or river
mean sea level the average height of the sea surface over a 19-year period
mean sea level
measurement a determination of the dimensions of something using a standard unit
mechanical advantage a number that tells how many times a machine multiplies force; it can be calculated by dividing the output force by the input force
mechanical advantage
mechanical efficiency the ratio of output to input of energy or of power; it can be calculated by dividing work output by work input
mechanical efficiency
mechanical energy the amount of work an object can do because of the object's kinetic and potential energies
mechanical energy
mechanical wave a wave that requires a medium through which to travel
mechanical wave
mechanical weatheringthe process by which rocks break down into smaller pieces by physical means
mechanical weathering
medial moraine a ridge of unsorted glacial material in the middle of a glacier
medial moraine
medicineany drug that is used to cure, prevent, or treat illness or discomfort
Mediterranean climate a climate that has long, sunny, hot, and dry summers and rainy winters; found on the coasts and islands of the Mediterranean Sea and in Southern California
Mediterranean climate
medium a physical environment in which phenomena occur
medulla the innermost portion of an organ, such as the kidney
medulla oblongata in fish, the posterior brain lobes that regulate the internal organs; in humans, the lower portion of the brain stem, which regulates circulation, respiration, and certain special senses
medulla oblongata
medusa a free-swimming, jellyfish-like, and often umbrella-shaped sexual stage in the life cycle of a cnidarian; also a jellyfish or a hydra
megagametophyte the female gametophyte of a heterosporus plant
megasporangium a structure that produces megaspores
megaspore the larger of the two types of spores produced by heterosporous plants; develops into a female gametophyte
megaspore mother cell a diploid cell that undergoes meiosis to produce four haploid megaspores
megaspore mother cell
meiosis a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells (gametes or spores)
melanin a pigment that helps determine skin color
melatonin a hormone that is produced by the pineal gland during the night and that helps regulate certain biorhythms, such as sleep patterns
melting the change of state in which a solid becomes a liquid by adding heat or changing pressure
melting point the temperature and pressure at which a solid becomes a liquid
melting point
meltwater water that forms when ice or snow melts, especially glacier ice
membrane potential the difference in electric potential between the two sides of a cell membrane
membrane potential
memory B cella B cell that responds to an antigen more strongly when the body is reinfected with an antigen than it does during its first encounter with the antigen
memory B cell
memory cell an immune system B cell or T cell that does not respond the first time that it meets with an antigen or an invading cell but that recognizes and attacks the antigen or invading cell during subsequent infections
memory cell
meninges the three protective membranes that cover the brain and spinal cord
meniscus the curve at a liquid's surface by which one measures the volume of the liquid
menopause the termination of the menstrual cycle; occurs between the ages of 45 and 55
menstrual cycle the female reproductive cycle, characterized by a monthly change of the lining of the uterus and the discharge of blood
menstrual cycle
menstruation the discharge of blood and discarded tissue from the uterus during the menstrual cycle
Mercalli scale a 12-step system used for measuring the intensity of an earthquake
Mercalli scale
Mercator projection a map projection that is made when the contents of the globe are moved onto a cylinder; the meridians appear as straight, parallel, and evenly spaced lines, and the parallels appear as straight, unevenly spaced lines perpendicular to the meridians
Mercator projection
meridian any semicircle that runs north and south around Earth from the geographic North Pole to the geographic South Pole; a line of longitude
meristem a region of undifferentiated plant cells that are capable of dividing and developing into specialized plant tissues
mesa a flat-topped hill that rises steeply from a surrounding plain
mesentery a membrane that attaches the small intestine to the abdominal wall
mesoderm in an embryo, the middle layer of cells that gives rise to muscles, blood, and various systems
mesoglea in cnidarians, the jellylike material located between the ectoderm and the endoderm
mesopause the upper boundary of the mesosphere, marked by an increase in temperature
mesophyll in leaves, the tissue between epidermal layers, where photosynthesis occurs
mesosphere literally, the "middle sphere"; the strong, lower part of the mantle between the asthenosphere and the outer core
mesospherethe coldest layer of the atmosphere, between the stratosphere and the thermosphere, in which temperature decreases as altitude increases
mesothorax the middle segment of an insect's thorax
Mesozoic era the geologic era that lasted from 251 million to 65.5 million years ago; also called the Age of Reptiles
Mesozoic era
metabolism the sum of all chemical processes that occur in an organism
metal an element that is shiny and that conducts heat and electricity well
metallic bond a bond formed by the attraction between positively charged metal ions and the electrons around them
metallic bond
metalloid elements that have properties of both metals and nonmetals; sometimes referred to as semiconductors
metamorphic rock a rock that forms from other rocks as a result of intense heat, pressure, or chemical processes
metamorphic rock
metamorphism the process in which one type of rock changes into metamorphic rock because of chemical processes or changes in temperature and pressure
metamorphosis a phase in the life cycle of many animals during which a rapid change from the immature organism to the adult takes place; an example is the change from larva to adult in insects
metamorphosisone of the stages of mitosis and meiosis, during which all of the chromosomes move to the cell's equator
metathorax the third and most posterior segment of an insect's thorax
meteor a bright streak of light that results when a meteoroid burns up in Earth's atmosphere
meteorite a meteoroid that reaches the Earth's surface without burning up completely
meteoroid a relatively small, rocky body that travels through space
meteorology the scientific study of Earth's atmosphere, especially in relation to weather and climate
meteor shower a phenomenon that occurs when a group of meteors burn up upon entering the Earth's atmosphere
meteor shower
meter the basic unit of length in the SI (symbol, m)
methanogen a microorganism that produces methane gas
microclimate the climate of a small area
micronucleus the smaller, reproductive nucleus found in some protozoans
micronutrient a chemical needed in very small amounts for plant growth, such as manganese, iron, and zinc
microprocessor a single semiconductor chip that controls and executes a microcomputer's instructions
micropyle the small opening in the wall of an ovule through which a pollen tube enters the ovule
microscope an instrument that produces an enlarged image of an object
microsporangium the structure that produces microspores in plants that produce two types of spores
microspore the smaller of the two types of spores produced by most plants that develops into the male gametophyte
microtubule one of the small, tubular fibers composed of the protein tubulin that are found in the cytoplasm of eukaryotic cells, that compose the cytoskeleton, and that play a role in cell structure and movement
microvillus a fingerlike projection from the surface of certain animal cells, such as the epithelial cells that line the intestine, that increases the cell's surface area for absorption
mid-Atlantic ridge a long and steep elevation of the sea floor that extends from north to south in the Atlantic Ocean
mid-Atlantic ridge
midbrain the section of the brain stem that is between the thalamus and the pons
middle ear the part of the ear that is between the eardrum and the cochlea; contains the hammer, anvil, and stirrup
middle ear
middle-latitude climatea climate that has a maximum average temperature of 8°C in the coldest month and a minimum average temperature of 10°C in the warmest month
middle-latitude climate
midgut the main digestive cavity of some invertebrates
mid-latitude cyclonean area of low pressure that is characterized by rotating wind that moves toward the rising air of the central low-pressure region; the motion is counterclockwise in the Northern Hemisphere
mid-latitude cyclone
mid-ocean ridge a long, undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the asthenosphere, and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart
mid-ocean ridge
migrate to move from one place to another when the seasons change
migration in general, any movement of individuals or populations from one location to another; specifically, a periodic group movement that is characteristic of a given population or species
Milankovitch cyclescyclical changes in Earth's orbit and in the tilt of Earth's axis that occur over thousands of years and are thought to cause climatic changes
Milankovitch cycles
Milankovitch theory the theory that cyclical changes in Earth's orbit and in the tilt of Earth's axis occur over thousands of years and cause climatic changes
Milankovitch theory
millimeter of mercury a unit of pressure
millimeter of mercury
mimicry a defense in which one organism resembles another that is dangerous or poisonous
mineral a natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties
mineralogist a person who examines, analyzes, and classifies minerals
mineral resources the valuable mineral deposits of a region
mineral resources
miscible describes two or more liquids that can dissolve into each other in various proportions
mistral a strong, cold, northern wind that blows down the Alps toward the Mediterranean Sea
mitochondrial matrix the fluid that is inside the inner membrane of a mitochondrion
mitochondrial matrix
mitochondrion in eukaryotic cells, the cell organelle that is surrounded by two membranes and that is the site of cellular respiration, which produces ATP
mitosis in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes
mitotic spindle a group of microtubules that forms during mitosis and separates the chromatids during nuclear division
mitotic spindle
mitral valve one of the four valves of the heart that is located between the left atrium and the left ventricle
mitral valve
mixture a combination of two or more substances that are not chemically combined
mitotic spindle a pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept
mitotic spindle
moderator a material that slows the velocity of neutrons so that they may be absorbed by the nuclei
modulate to change a wave's amplitude or frequency in order to send a signal
Moho the Mohorovicic discontinuity, which is the boundary between the Earth's crust and mantle where the speed of seismic waves suddenly changes
Mohs hardness scale the standard scale against which the hardness of minerals is rated
Mohs hardness scale
molal boiling-point constant a quantity calculated to represent the boiling-point elevation of a 1-molal solution of a nonvolatile, nonelectrolyte solution
molal boiling-point constant
molal freezing-point constant a quantity calculated to represent the freezing-point depression of a 1-molal solution of a nonvolatile, nonelectrolyte solute
molal freezing-point constant
molality the concentration of a solution expressed in moles of solute per kilogram of solvent
molar a large tooth that is located in the back of the mouth and that is used to grind and crush food
molarity a concentration unit of a solution expressed as moles of solute dissolved per liter of solution
molar mass the mass in grams of 1 mol of a substance
molar mass
mold in biology, a fungus that looks like wool or cotton
mold in geology, a mark or cavity made in a sedimentary surface by a shell or other body
mole the SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly12 g of carbon-12
molecular formula a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms
molecular formula
molecular genetics the study of the structure of nucleic acids and the function and regulation of genes
molecular genetics
mole ratio the relative number of moles of the substances required to produce a given amount of product in a chemical reaction
mole ratio
mollusk an invertebrate that has a soft, bilaterally symmetrical body that is often enclosed in a hard shell made of calcium carbonate; examples include snails, clams, octopuses, and squids
molting the shedding of an exoskeleton, skin, feathers, or hair to be replaced by new parts
moment of inertia the tendency of a body that is rotating about a fixed axis to resist a change in this rotating motion
moment of inertia
momentum a quantity defined as the product of the mass and velocity of an object
monadnock an isolated hill of rock that has resisted erosion
monatomic ion an ion that formed from a single atom
monatomic ion
monocline a fold in rock layers in which the layers are horizontal on both sides of the fold
monocotamonocotyledonous plant; a plant that produces seeds that have only one cotyledon
monohybrid cross a cross between individuals that involves one pair of contrasting traits
monohybrid cross
monomer a simple molecule that can combine with other like or unlike molecules to make a polymer
an acid that can donate only one proton to a base
monoprotic acid
monosaccharide a simple sugar that is the basic subunit of a carbohydrate
monosomy a condition in a diploid cell in which one member of a pair of homologous chromosomes is missing
monotreme a mammal that lays eggs
monsoon a seasonal wind that blows toward the land in the summer, bringing heavy rains, and that blows away from the land in the winter, bringing dry weather
month a division of the year that is based on the orbit of the moon around the Earth
moon a body that revolves around a planet and that has less mass than the planet does
morainea landform that is made from unsorted sediments deposited by a glacier
morphogenesis the development of shape in cells, tissues, or the entire embryo
morphology the study of the structure and form of an organism
mortality rate the number of deaths that occur in a given period of time
mortality rate
morula a ball of cells that is produced by cleavage of the zygote
motion an object’s change in position relative to a reference point
motor neuron a nerve cell that conducts nerve impulses from the central nervous system to the muscles and glands
motor neuron
mountain range a series of mountains that are closely related in orientation, age, and mode of formation
mountain range
M phase the phase of the cell cycle in which the nucleus divides by mitosis
M phase
mRNA messenger RNA, a single-stranded RNA molecule that encodes the information to make a protein
Muav Limestone a rock layer of the Grand Canyon that was deposited during the Cambrian period
Muav Limestone
the layer of epithelial tissue that covers internal surfaces of the body and that secretes mucus
mucous membrane
mucus the thick, slimy fluid that is secreted by mucous membranes and glands
mud a wet mixture of fine particles of clay and silt
mudflow the flow of a mass of mud or rock and soil mixed with a large amount of water
mud pots a hot spring that discharges boiling mud
mud pots
multicellular describes a tissue, organ, or organism that is made of many cells
multinucleate describes a cell that has more than one nucleus
multiple alleles more than two alleles (versions of the gene) for a genetic trait
multiple alleles
multiple bond a bond in which the atoms share more than one pair of electrons, such as a double bond or a triple bond
multiple bond
municipal solidwastewaste produced by households and businesses
municipal solid waste
muscle fiber a multinucleate muscle cell, especially of skeletal or cardiac muscle tissue
muscle fiber
muscle tissue the tissue made of cells that can contract and relax to produce movement
muscle tissue
muscular system a collection of muscles whose primary function is movement and flexibility
muscular system
mutagen a physical or chemical agent that can damage or cause changes (mutations) in DNA
mutation a change in the nucleotide-base sequence of a gene or DNA molecule
mutual inductance the ability of one circuit to induce an electromotive force in a nearby circuit in the presence of a changing current
mutual inductance
mutualism a relationship between two species in which both species benefit
mycelium the mass of fungal filaments, or hyphae, that forms the body of a fungus
myceliumthe study of fungi
mycorrhiza a symbiotic association between fungi and plant roots
myelin sheath a layer of fatty material that surrounds certain nerve fibers and that acts as an electrical insulator
myelin sheath
myofibril a fiber that is found in striated muscle cells and that is responsible for muscle contraction
myosin the most abundant protein in muscle tissue and the main constituent of the thick filaments of muscle fibers
myriapod an arthropod that has more than three pairs of legs