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141 Cards in this Set

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G0 phase the nondividing state that a cell may enter instead of completing the cell cycle
G0 phase
G1 phase the first growth period of interphase, prior to DNA synthesis
G1 phase
G2 phase the second growth period of interphase, starting at the end of DNA synthesis and ending when mitosis begins
G2 phase
galaxy a collection of stars, dust, and gas bound together by gravity
Galilean moon any one of the four largest satellites of Jupiter—Io, Europa, Ganymede, and Callisto—that were discovered by Galileo in 1610
Galilean moon
gallbladder a sac-shaped organ that stores bile produced by the liver
galvanometer an instrument that detects, measures, and determines the direction of a small electric current
gametangium a cell or an organ that produces gametes
gamete a haploid reproductive cell that unites with another haploid reproductive cell to form a zygote
gametocyte a cell that is not differentiated and that develops into a gamete
gametophyte in alternation of generations, the phase in which gametes are formed; a haploid individual that produces gametes
gametophyte in alternation of generations,
gamma decay the release of gamma rays from the nucleus of an atom
gamma decay
gamma ray the high-energy photon emitted by a nucleus during fission and radioactive decay
gamma ray
ganglion a mass of nerve cells
gas a form of matter that does not have a definite volume or shape
gas giant a planet that has a deep, massive atmosphere, such as Jupiter, Saturn, Uranus, or Neptune
gas giant
gas laws the laws that state the mathematical relationships between the volume, temperature, pressure, and quantity of a gas
gas laws
gasohol a mixture of gasoline and alcohol that is used as a fuel
gastric cecum a pouch that branches from the digestive tract of an insect
gastric cecum
gastric fluid a liquid secreted by gastric glands in the stomach
gastric fluid
gastrin a hormone that stimulates the stomach to secrete hydrochloric acid and pepsin
gastrodermis In cnidarians, the layer of cells surrounding the digestive tract
gastrointestinal tract the digestive tract from the mouth to the anus, including the stomach and intestines
gastrointestinal tract
gastrolith a stone that is found within the digestive system of certain animals and that helps grind food in digestion
gastropod a mollusk that has a well-developed head and a flattened foot, such as a snail, slug, or conch
gastrovascular cavity a cavity that serves both digestive and circulatory purposes in some cnidarians
gastrovascular cavity
gastrula the embryo in the stage of development after the blastula; contains the embryonic germ layers
gastrulation the transformation of the blastula into the gastrula or the formation of the embryonic germ layers
Gay-Lussac's law the law that states that the volume occupied by a gas at a constant pressure is directly proportional to the absolute temperature
Gay-Lussac's law
Gay-Lussac's law of combining volumes of gases the law that states that the volumes of gases involved in a chemical change can be represented by the ratio of small whole numbers
Gay-Lussac's law of combining volumes of gases
Geiger-Muller counter an instrument that detects and measures the intensity of radiation by counting the number of electric pulses that pass between the anode and the cathode in a tube filled with gas
Geiger-Muller counter
gel electrophoresis a technique used to separate nucleic acids or proteins according to size and charge in an agarose or acryl amide gel
gel electrophoresis a
gem mule an asexual reproductive structure produced by some freshwater sponges
gemstone a mineral, rock, or organic material that can be used as jewelry or an ornament when it is cut and polished
gene a segment of DNA that is located in a chromosome and that codes for a specific hereditary trait
gene cloning the process of isolating a gene sequence in the genome of an organism and inserting the gene sequence into a plasmid vector for production in large numbers
gene cloning
gene expression The manifestation of the genetic material of an organism in the form of specific traits
gene expression
gene flow the movement of genes into or out of a population due to interbreeding
gene flow
gene pool all of the genes of the reproductively active members of a population
gene pool
generalist a species that has a broad niche such that the species can tolerate a wide range of conditions and can use a variety of resources
generation time the period between the birth of one generation and the birth of the next generation
generation time
generative cell in a pollen grain, the cell that divides mitotic ally and forms two sperm cells
generator a machine that converts mechanical energy into electrical energy
gene therapy a technique that places a gene into a cell to correct a hereditary disease or to improve the genome
gene therapy
genetic code the rule that describes how a sequence of nucleotides, read in groups of three consecutive nucleotides (triplets) that correspond to specific amino acids, specifies the amino acid sequence of a protein
genetic code
genetic counseling the process of testing and informing potential parents about their genetic makeup and the likelihood that they will have offspring with genetic defects or hereditary diseases
genetic counseling
genetic disorder an inherited disease or disorder that is caused by a mutation in a gene or by a chromosomal defect
genetic disorder
genetic drift the random change in allele frequency in a population
genetic drift
genetic engineering a technology in which the genome of a living cell is modified for medical or industrial use
genetic engineering
genetic equilibrium the stability of gene frequencies in a population across generations
genetic equilibrium
genetic marker a gene whose phenotype is easily identified
genetic marker
genetic recombinationthe regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents
genetic recombination
genetics the science of heredity and of the mechanisms by which traits are passed from parents to offspring
genetic screening an examination of a person's genetic makeup
genetic screening
genital herpes a sexually transmitted disease that is caused by a herpes simplex virus
genital herpes
genome the complete genetic material contained in an individual
genomic library a set of cloned fragments of DNA that together represent the entire genome
genomic library
genotype the entire genetic makeup of an organism; also the combination of genes for one or more specific traits
genotypic ratio the ratio of the genotypes that appear in offspring
genotypic ratio
genus the level of classification that comes after family and that contains similar species
geocentric describes something that uses the Earth as the reference point
geographic information system an automated system for capturing, storing, retrieving, analyzing, manipulating, and displaying geographic data (abbreviation, GIS)
geographic information system
geographic isolation the physical separation of populations due to geographic barriers that prevent interbreeding
geographic isolation
geologic column an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom
geologic column
geologic time scale the standard method used to divide the Earth's long natural history into manageable parts
geologic time scale
geology the scientific study of the origin, history, and structure of Earth and the processes that shape Earth
geomagnetic poles a point on the Earth's surface above a pole of the Earth's imaginary internal magnet
geomagnetic poles
geometric isomers compounds that exist in two or more geometrically different configurations
geometric isomers
the mostly solid, rocky part of the Earth; extends from the center of the core to the surface of the crust
geostationary orbit an orbit that is about 36,000 km above Earth's surface and in which a satellite is above a fixed spot on the equator
geostationary orbit
geosynchronous orbit an orbit in which a satellite moves in the same direction as Earth's rotation such that the satellite remains at an altitude or 35,880 km above Earth's surface
geosynchronous orbit
geothermal energy the energy produced by heat within Earth
geothermal energy
germination the beginning of growth or development in a seed, spore, or zygote, especially after a period of inactivity
one of the three cell layers present in an embryo
germ layer
germ plasm hereditary material (chromosomes and genes) that is usually contained in the protoplasm of germ cells
germ plasm
gestation In mammals, the process of carrying young from fertilization to birth
gestation period in mammals, the length of time between fertilization and birth
gestation period
geysers a hot spring that periodically discharges hot water and steam
giant a very large and bright star whose hot core has used most of its hydrogen
giardiasis an illness caused by the parasitic protozoan Giardia and characterized by diarrhea
gibberellins a plant hormone that stimulates growth of stems and leaves
gill in mushrooms, a structure that is located on the underside of the cap and bears the spores
gill in mushrooms,
gill in aquatic animals, a respiratory structure that consists of many blood vessels surrounded by a membrane that allows for gas exchange
gill in aquatic animals,
gill arch one of the jointed and cartilaginous or bony structures behind the jaws in fish and larval amphibians
gill arch
gill slit a perforation between two gill arches through which water taken in through the mouth of a fish passes over the gills and out of the fish's body
gill slit
gizzard an enlargement of the digestive tract of some invertebrates, such as annelids and insects, that grinds food; a muscular region in the digestive tract of birds that grinds and softens food
glacial drift the rock material carried and deposited by glaciers
glacial drift
glacial period a period of cooler climate that occurs during an ice age and that is characterized by the advancement of glaciers
glacial period
glacier a large mass of moving ice
gland a group of cells that make special chemicals for the body
global ocean the body of salt water that covers nearly three-fourths of Earth’s surface
global ocean
global positioning system a network of satellites that orbit the Earth to measure positions on the Earth's surface (abbreviation, GPS)
global positioning system
global warming a gradual increase in the average global temperature that is due to a higher concentration of gases such as carbon dioxide in the atmosphere
global warming
globular cluster a tight group of stars that looks like a ball and contains up to 1 million stars
globular cluster
glomerulus a cluster of capillaries that is enclosed in a Bowman's capsule in a nephron of the kidney, where blood is filtered
glucagon a hormone that is produced in the pancreas and that raises the blood glucose level
glycolysis the anaerobic breakdown of glucose pyruvic acid, which makes a small amount of energy available to cells in the form of ATP
glycoprotein a protein to which carbohydrate molecules are attached
gnomonic projection a map projection in which the points on the surface of a sphere are projected from the center of the sphere onto a plane that is tangent to the sphere
gnomonic projection
goiter an enlargement of the thyroid gland that causes the neck to swell
Golgi complex a cell organelle that helps make and package materials to be transported out of the cell
Golgi complex
gonad an organ that produces gametes
Gondwanaland the southern landmass that supposedly fragmented millions of years ago to form South America, Africa, India, Australia, and Antarctica
gonorrhea a sexually transmitted disease that is caused by bacteria and that results in inflammation of the mucous membranes in the urinary and reproductive tracts
graben a long, narrow crustal block between two parallel faults
gradient the change in elevation over a given distance
gradualism a model of evolution in which gradual change over a long period of time leads to biological diversity
grafting a technique in which a portion of one plant is attached to the root or shoot of another plant and grows there
Graham's law of diffusion the law that states that the rate of diffusion of a gas is inversely proportional to the square root of the gas's density
Graham's law of diffusion
grain the edible seed or seed like fruit of a cereal grass
Gram-negative bacterium a bacterium that loses the Gram stain and usually has an outer covering on its cell wall
Gram-negative bacterium
Gram-positive bacterium a bacterium that retains the Gram stain and usually lacks an outer covering on its cell wall
Gram-positive bacterium
Gram stain a series of dyes used to classify bacteria; depending on the chemistry of the bacterial cell wall, bacteria will either retain or lose the stain
Gram stain
granum a stack of hyaloids in a chloroplast
graphite a soft, black, crystalline form of carbon that is a fair conductor of electricity
gravitational force the force of attraction between massive bodies that is due to gravitation
gravitational force
gravitational potential energy the potential energy stored in the gravitational fields of interacting bodies
gravitational potential energy
gravitropism the growth of a plant in a particular direction in response to gravity
gravity a force of attraction between objects that is due to their masses and that decreases as the distance between the objects increases
great ape an ape whose face has little hair and whose hands have nails and complex fingerprints, such as an orangutan, gorilla, or chimpanzee
great ape
great circle any circle that divides the globe in half; represents the shortest distance between any two points on the Earth's surface
great circle
green gland an excretory organ of some crustaceans that is located at the base of the antennae
green gland
greenhouse effect the warming of the surface and lower atmosphere of Earth that occurs when carbon dioxide, water vapor, and other gases in the air absorb and reradiate infrared radiation
greenhouse effect
greenhouse gases a gas composed of molecules that absorb and radiate infrared radiation from the sun
greenhouse gases
Gregorian calendar the calendar that is used in the modern industrial world and in which a year consists of 365 days (plus one extra day every four years) and years are numbered from the birth of Jesus Christ
Gregorian calendar
gross primary productivity the rate at which organic matter is assimilated by plants and other producers during a period of time over a certain area
gross primary productivity
ground moraine the rock debris left by a glacier or ice sheet
ground moraine
ground state the lowest energy state of a quantized system
ground state
ground tissue a type of plant tissue other than vascular tissue that makes up much of the inside of a plant
ground tissue
groundwater the water that is beneath the Earth's surface
group a vertical column of elements in the periodic table; elements in a group share chemical properties
growth factor a substance that is needed to allow cell multiplication
growth factor
growth hormone a hormone that is secreted by the anterior lobe of the pituitary gland and that regulates the growth of most tissues (abbreviation, GH)
growth hormone
growth rate an expression of the increase in the size of an organism or population over a given period of time
growth rate
growth regulator an organic compound that stimulates or inhibits physiological processes in plants
growth regulator
guanine one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; guanine pairs with cytosine
guard cell one of a pair of specialized cells that border a stoma and regulate gas exchange
guard cell
Gulf Stream the swift, deep, and warm Atlantic current that flows along the eastern coast of the United States toward the northeast
Gulf Stream
gut the digestive tract
gymnosperm a woody, vascular seed plant whose seeds are not enclosed by an ovary or fruit
gyre a huge circle of moving ocean water found above and below the equator