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129 Cards in this Set
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habitat the place where an organism usually lives
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habitat
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habitat conservation plan a land-use plan that attempts to protect threatened or endangered species across a given area by allowing some trade-offs between harm to the species and additional conservation commitments among cooperating parties
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habitat conservation plan
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hadal zone the deep zone of the ocean, below 6,000 m
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hadal zone
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hail a type of precipitation in the form of lumps of ice
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hail
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hair in mammals, one of the many long and thin structures that grow out from the skin
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hair
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hair follicle a depression in the skin that encloses a hair and its root
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hair follicle
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hair hygrometer an instrument that uses human hair to measure relative humidity; human hair stretches as humidity increases
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hair hygrometer
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half-cell a single electrode immersed in a solution of its ions
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half-cell
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half-life the time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
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half-life
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half-reaction the part of a reaction that involves only oxidation or reduction
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half-reaction
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halogen one of the elements of Group 17 of the periodic table (fluorine, chlorine, bromine, iodine, and astatine); halogens combine with most metals to form salts
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halogen
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hanging valley a small glacial valley that opens above the floor of the main valley
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hanging valley
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hanging wall the rock above a fault plane
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hanging wall
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haploid describes a cell, nucleus, or organism that has only one set of unpaired chromosomes
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haploid
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hardness a measure of the ability of a mineral to resist scratching
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hardness
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hard palate the bony part of the palate
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hard palate
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hardware the parts or pieces of equipment that make up a computer
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hardware
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hard water water that contains relatively large amounts of dissolved minerals
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hard water
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Hardy-Weinberg principle the principle that states that the frequency of alleles in a population does not change unless evolutionary forces act on the population
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Hardy-Weinberg principle
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harmonic series a series of frequencies that includes the fundamental frequency and integral multiples of the fundamental frequency
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harmonic series
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Haversian canal a channel containing blood vessels in compact bone tissue
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Haversian canal
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a pollen allergy that results in sneezing, a runny nose, and watering eyes
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hay fever
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hazardous wastes wastes that are a risk to the health of humans or other living organisms
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hazardous wastes
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head-foot the regions of a mollusk body that consist of the head and the foot
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head-foot
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headland a high and steep formation of rock that extends out from shore into the water
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headland
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headward erosion the lengthening of a valley or stream by erosion of the valley head
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headward erosion
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headwaters the water upstream from a dam
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headwaters
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heart attack the death of heart tissues due to a blockage of their blood supply
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heart attack
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the non conducting older wood in the center of a tree trunk
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heartwood
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heartworm disease in dogs, a disease of the heart and large arteries that is caused by a filarial worm
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heartworm disease
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heat the energy transferred between objects that are at different temperatures; energy is always transferred from higher-temperature objects to lower-temperature objects until thermal equilibrium is reached
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heat
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heat engine a machine that transforms heat into mechanical energy, or work
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heat engine
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heat island an area in which the air temperature is generally higher than the temperature of surrounding rural areas
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heat island
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heat of combustion the energy released as heat by the complete combustion of a specific amount of a substance at constant pressure or constant volume
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heat of combustion
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heat of formation the increase in enthalpy resulting from the formation of 1 mol of a substance at constant pressure
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heat of formation
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heat of fusion the increase in enthalpy accompanying the conversion of 1 mol of a solid to a liquid at its melting point at a constant pressure and temperature
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heat of fusion
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heat of fusion the amount of heat required to change a substance from solid to liquid at constant temperature and pressure
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heat of fusion
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heat of reaction the amount of heat released or absorbed during a chemical reaction
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heat of reaction
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heat of solution the amount of heat energy absorbed or released when a specific amount of solute dissolves in a solvent
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heat of solution
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heat of vaporization the quantity of energy required to evaporate 1 mol of a liquid at constant pressure and temperature
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heat of vaporization
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Heisenberg uncertainty principal the principle that states that determining both the position and velocity of an electron or any other particle simultaneously is impossible
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Heisenberg uncertainty principal the
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helicase an enzyme that separates DNA strands
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helicase
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heliocentric sun-centered
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heliocentric
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helper T cell a white blood cell necessary for B cells to develop normal levels of antibodies
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helper T cell
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hemocoel the blood-filled space or body cavity of some invertebrates
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hemocoel
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hemoglobin the oxygen-carrying pigment in red blood cells
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hemoglobin
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hemoglobin the fluid that circulates through the body of an animal that has an open circulatory system
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hemoglobin
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hemophilia a genetic disease in which the blood lacks a protein that is essential for clotting
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hemophilia
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Henry's law the law that states that at constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas on the surface of the liquid
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Henry's law
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hepatic portal circulation the system of blood movement through the small intestine to the liver
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hepatic portal circulation
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hepatitis an inflammation of the liver
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hepatitis
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herb a flowering, vascular seed plant that lacks a woody stem; a plant part used to add flavor to food, to make medicine, or to make a perfume
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herb
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herbaceous plant a plant that is soft and green instead of woody
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herbaceous plant
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herbicide a chemical substance used to destroy unwanted vegetation, such as weeds and grasses
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herbicide
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herbivore an organism that eats only plants
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herbivore
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heredity the passing of genetic traits from parent to offspring
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heredity
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hermaphrodite an organism that has both male and female reproductive organs
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hermaphrodite
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Hess's law the law that states that the amount of heat released or absorbed in a chemical reaction does not depend on the number of steps in the reaction
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Hess's law
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heterogeneous composed of dissimilar components
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heterogeneous
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a catalyst that is in a different phase from the phase of the reactants
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heterogeneous catalyst
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heterogeneous reaction a reaction in which the reactants are in two different phases
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heterogeneous reaction
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heterospory the production of two or more kinds of asexual spores
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heterospory
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heterotroph an organism that obtains organic food molecules by eating other organisms or their byproducts and that cannot synthesize organic compounds from inorganic materials
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heterotroph
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heterozygous describes an individual that has two different alleles for a trait
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heterozygous
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hibernation a period of inactivity and lowered body temperature that some animals undergo in winter as a protection against cold weather and lack of food
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hibernation
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hilum on a plant seed, a scar that marks where the seed was attached to the ovary wall
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hilum
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hindgut the embryonic structure that develops into the large intestine
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hindgut
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hinge joint a joint in which the surface of one bone fits into the surface of another to allow the bone to move back and forth like a hinged door
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hinge joint
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histamine a chemical that stimulates the autonomous nervous system, secretion of gastric juices, and dilation of capillaries
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histamine
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histone a type of protein molecule found in the chromosomes of eukaryotic cells but not prokaryotic cells
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histone
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HIV humaimmunodeficiency virus, the virus that causes AIDS
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HIV human
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holdfast the part of an alga that anchors the alga to a substrate
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holdfast
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hole an energy level that is not occupied by an electron in a solid
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hole
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hologram a piece of film on which an interference pattern produces a three-dimensional image of an object
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hologram
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homeobox a DNA sequence within a homeotic gene that regulates development in animals
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homeobox
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homeostasis the maintenance of a constant internal state in a changing environment; a constant internal state that is maintained in a changing environment by continually making adjustments to the internal and external environment
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homeostasis
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homeotic gene a gene that controls the development of a specific adult structure
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homeotic gene
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hominid a member of the family Hominidae of the order Primates; characterized by bipedalism, relatively long lower limbs, and lack of a tail; examples include humans and their ancestors
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hominid
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homogeneous describes something that has a uniform structure or composition throughout
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homogeneous
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homogeneous catalyst a catalyst that is in the same phase as the reactants are
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homogeneous catalyst
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a reaction in which all of the reactants and products are in the same phase
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homogeneous reaction
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homologouschromosomes chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis
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Homologous
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homologous series a series of organic compounds in which adjacent members differ by some radical, usually CH2, and have one more radical than the previous member does
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homologous series
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homologous structures anatomical structures that share a common ancestry
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homologous structures
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Homo sapiens the species of hominids that includes modern humans and their closest ancestors and that first appeared about 100,000 to 150,000 years ago
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Homo sapiens
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homospory the production of only one kind of spore
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homospory
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homozygous describes an individual that has identical alleles for a trait on both homologous chromosomes
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homozygous
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hookworm a parasitic roundworm found in the intestines of mammals
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hookworm
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horizon the line where the sky and the Earth appear to meet; also a horizontal layer of soil that can be distinguished from the layers above and below it; also a boundary between two rock layers that have different physical properties
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horizon
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hormone a substance that is made in one cell or tissue and that causes a change in another cell or tissue located in a different part of the body
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hormone
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horn a sharp, pyramid-like peak that forms because of the erosion of cirques
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horn
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horse latitudes latitudes of approximately 30º to 35º north and south, where winds are calm and light and the weather is hot and dry
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horse latitudes
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host an organism from which a parasite takes food or shelter
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host
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hot spot a volcanically active area of Earth's surface, commonly far from a tectonic plate boundary
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hot spot
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hot spring groundwater that rises to the surface and that is at a temperature higher than the temperature of the human body
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hot spring
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H-R diagram Hertzsprung-Russell diagram, a graph that shows the relationship between a star’s surface temperature and absolute magnitude
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H-R diagram
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human chorionic gonadotropin a hormone that is secreted by the placenta and that stimulates ovulation and secretion of progesterone or testosterone (abbreviation, HCG)
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human chorionic gonadotropin
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Human Genome Project a research effort to sequence and locate the entire collection of genes in human cells
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Human Genome Project
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humidity the amount of water vapor in the air
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humidity
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humoral immunity a type of immunity that is produced by the action of antibodies in the body fluids such as blood plasma or lymph
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humoral immunity
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humus dark, organic material formed in soil from the decayed remains of plants and animals
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humus dark,
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Hund's rule the rule that states that for an atom in the ground state, the number of unpaired electrons is the maximum possible and these unpaired electrons have the same spin
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Hund's rule
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hunter-gatherers people who obtain their food by hunting and gathering wild animals and plants
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hunter-gatherers
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Huntington's disease a rare hereditary disease of the brain characterized by involuntary movements of the limbs or face, decreasing mental abilities, and eventual death
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Huntington's disease
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hurricane a severe storm that develops over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely low-pressure storm center
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hurricane
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hybridization the mixing of two or more atomic orbitals of the same atom to produce new orbitals; hybridization represents the mixing of higher- and lower-energy orbitals to form orbitals of intermediate energy
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hybridization
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hybrid orbitals orbitals that have the properties to explain the geometry of chemical bonds between atoms
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hybrid orbitals
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hydration the strong affinity of water molecules for particles of dissolved or suspended substances that causes electrolytic dissociation
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hydration
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hydrocarbon an organic compound composed only of carbon and hydrogen
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hydrocarbon
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hydroelectric energy a electrical energy produced by the flow of water
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hydroelectric energy
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hydrogen bond the intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule
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hydrogen bond
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hydrolysis a chemical reaction between water and another substance to form two or more new substances; a reaction between water and a salt to create an acid or a base
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hydrolysis
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hydronium ion an ion consisting of a proton combined with a molecule of water; H3O+
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hydronium ion
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hydrophilic describes the molecular attraction to water
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hydrophilic
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hydrophobic describes the molecular repulsion of water
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hydrophobic
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hydrosphere the portion of Earth that is water
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hydrosphere
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hydrostatic skeleton in many invertebrates, the cavity that is filled with water and that has a support function
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hydrosphere skeleton
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hydroxide ion the OH– ion
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hydroxide ion
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hygiene the science of health and ways to preserve health
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hygiene
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hypertension a condition of high blood pressure
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hypertension
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hyperthyroidism a condition caused by an overproduction of thyroid hormones and marked by goiter, weight loss, and hyperactivity
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hyperthyroidism
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hypertonic describes a solution whose solute concentration is higher than the solute concentration inside a cell
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hypertonic
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hypha a nonreproductive filament of a fungus
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hypha
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hypocotyl the portion of the stem of a plant embryo that is between the cotyledons and the embryonic root
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hypocotyl
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hypoglycemia a condition in which the concentration of glucose in the blood is very low
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hypoglycemia
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hypothalamus the region of the brain that coordinates the activities of the nervous and endocrine systems and that controls many body activities related to homeostasis
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hypothalamus
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hypothesis a testable idea or explanation that leads to scientific investigation
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hypothesis
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hypothyroidism a condition caused by a deficiency of thyroid hormones and marked by fatigue, weight gain, and sensitivity to cold
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hypothyroidism
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hypotonic describes a solution whose solute concentration is lower than the solute concentration inside a cell
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hypotonic
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