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129 Cards in this Set

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  • Back
habitat the place where an organism usually lives
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
habitat conservation plan
hadal zone the deep zone of the ocean, below 6,000 m
hadal zone
hail a type of precipitation in the form of lumps of ice
hair in mammals, one of the many long and thin structures that grow out from the skin
hair follicle a depression in the skin that encloses a hair and its root
hair follicle
hair hygrometer an instrument that uses human hair to measure relative humidity; human hair stretches as humidity increases
hair hygrometer
half-cell a single electrode immersed in a solution of its ions
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
half-reaction the part of a reaction that involves only oxidation or reduction
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
hanging valley a small glacial valley that opens above the floor of the main valley
hanging valley
hanging wall the rock above a fault plane
hanging wall
haploid describes a cell, nucleus, or organism that has only one set of unpaired chromosomes
hardness a measure of the ability of a mineral to resist scratching
hard palate the bony part of the palate
hard palate
hardware the parts or pieces of equipment that make up a computer
hard water water that contains relatively large amounts of dissolved minerals
hard water
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
Hardy-Weinberg principle
harmonic series a series of frequencies that includes the fundamental frequency and integral multiples of the fundamental frequency
harmonic series
Haversian canal a channel containing blood vessels in compact bone tissue
Haversian canal
a pollen allergy that results in sneezing, a runny nose, and watering eyes
hay fever
hazardous wastes wastes that are a risk to the health of humans or other living organisms
hazardous wastes
head-foot the regions of a mollusk body that consist of the head and the foot
headland a high and steep formation of rock that extends out from shore into the water
headward erosion the lengthening of a valley or stream by erosion of the valley head
headward erosion
headwaters the water upstream from a dam
heart attack the death of heart tissues due to a blockage of their blood supply
heart attack
the non conducting older wood in the center of a tree trunk
heartworm disease in dogs, a disease of the heart and large arteries that is caused by a filarial worm
heartworm disease
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
heat engine a machine that transforms heat into mechanical energy, or work
heat engine
heat island an area in which the air temperature is generally higher than the temperature of surrounding rural areas
heat island
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
heat of combustion
heat of formation the increase in enthalpy resulting from the formation of 1 mol of a substance at constant pressure
heat of formation
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
heat of fusion
heat of fusion the amount of heat required to change a substance from solid to liquid at constant temperature and pressure
heat of fusion
heat of reaction the amount of heat released or absorbed during a chemical reaction
heat of reaction
heat of solution the amount of heat energy absorbed or released when a specific amount of solute dissolves in a solvent
heat of solution
heat of vaporization the quantity of energy required to evaporate 1 mol of a liquid at constant pressure and temperature
heat of vaporization
Heisenberg uncertainty principal the principle that states that determining both the position and velocity of an electron or any other particle simultaneously is impossible
Heisenberg uncertainty principal the
helicase an enzyme that separates DNA strands
heliocentric sun-centered
helper T cell a white blood cell necessary for B cells to develop normal levels of antibodies
helper T cell
hemocoel the blood-filled space or body cavity of some invertebrates
hemoglobin the oxygen-carrying pigment in red blood cells
hemoglobin the fluid that circulates through the body of an animal that has an open circulatory system
hemophilia a genetic disease in which the blood lacks a protein that is essential for clotting
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
Henry's law
hepatic portal circulation the system of blood movement through the small intestine to the liver
hepatic portal circulation
hepatitis an inflammation of the liver
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
herbaceous plant a plant that is soft and green instead of woody
herbaceous plant
herbicide a chemical substance used to destroy unwanted vegetation, such as weeds and grasses
herbivore an organism that eats only plants
heredity the passing of genetic traits from parent to offspring
hermaphrodite an organism that has both male and female reproductive organs
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
Hess's law
heterogeneous composed of dissimilar components
a catalyst that is in a different phase from the phase of the reactants
heterogeneous catalyst
heterogeneous reaction a reaction in which the reactants are in two different phases
heterogeneous reaction
heterospory the production of two or more kinds of asexual spores
heterotroph an organism that obtains organic food molecules by eating other organisms or their byproducts and that cannot synthesize organic compounds from inorganic materials
heterozygous describes an individual that has two different alleles for a trait
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
hilum on a plant seed, a scar that marks where the seed was attached to the ovary wall
hindgut the embryonic structure that develops into the large intestine
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
hinge joint
histamine a chemical that stimulates the autonomous nervous system, secretion of gastric juices, and dilation of capillaries
histone a type of protein molecule found in the chromosomes of eukaryotic cells but not prokaryotic cells
HIV humaimmunodeficiency virus, the virus that causes AIDS
HIV human
holdfast the part of an alga that anchors the alga to a substrate
hole an energy level that is not occupied by an electron in a solid
hologram a piece of film on which an interference pattern produces a three-dimensional image of an object
homeobox a DNA sequence within a homeotic gene that regulates development in animals
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
homeotic gene a gene that controls the development of a specific adult structure
homeotic gene
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
homogeneous describes something that has a uniform structure or composition throughout
homogeneous catalyst a catalyst that is in the same phase as the reactants are
homogeneous catalyst
a reaction in which all of the reactants and products are in the same phase
homogeneous reaction
homologouschromosomes chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis
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
homologous series
homologous structures anatomical structures that share a common ancestry
homologous structures
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
Homo sapiens
homospory the production of only one kind of spore
homozygous describes an individual that has identical alleles for a trait on both homologous chromosomes
hookworm a parasitic roundworm found in the intestines of mammals
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
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
horn a sharp, pyramid-like peak that forms because of the erosion of cirques
horse latitudes latitudes of approximately 30º to 35º north and south, where winds are calm and light and the weather is hot and dry
horse latitudes
host an organism from which a parasite takes food or shelter
hot spot a volcanically active area of Earth's surface, commonly far from a tectonic plate boundary
hot spot
hot spring groundwater that rises to the surface and that is at a temperature higher than the temperature of the human body
hot spring
H-R diagram Hertzsprung-Russell diagram, a graph that shows the relationship between a star’s surface temperature and absolute magnitude
H-R diagram
human chorionic gonadotropin a hormone that is secreted by the placenta and that stimulates ovulation and secretion of progesterone or testosterone (abbreviation, HCG)
human chorionic gonadotropin
Human Genome Project a research effort to sequence and locate the entire collection of genes in human cells
Human Genome Project
humidity the amount of water vapor in the air
humoral immunity a type of immunity that is produced by the action of antibodies in the body fluids such as blood plasma or lymph
humoral immunity
humus dark, organic material formed in soil from the decayed remains of plants and animals
humus dark,
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
Hund's rule
hunter-gatherers people who obtain their food by hunting and gathering wild animals and plants
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
Huntington's disease
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
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
hybrid orbitals orbitals that have the properties to explain the geometry of chemical bonds between atoms
hybrid orbitals
hydration the strong affinity of water molecules for particles of dissolved or suspended substances that causes electrolytic dissociation
hydrocarbon an organic compound composed only of carbon and hydrogen
hydroelectric energy a electrical energy produced by the flow of water
hydroelectric energy
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
hydrogen bond
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
hydronium ion an ion consisting of a proton combined with a molecule of water; H3O+
hydronium ion
hydrophilic describes the molecular attraction to water
hydrophobic describes the molecular repulsion of water
hydrosphere the portion of Earth that is water
hydrostatic skeleton in many invertebrates, the cavity that is filled with water and that has a support function
hydrosphere skeleton
hydroxide ion the OH– ion
hydroxide ion
hygiene the science of health and ways to preserve health
hypertension a condition of high blood pressure
hyperthyroidism a condition caused by an overproduction of thyroid hormones and marked by goiter, weight loss, and hyperactivity
hypertonic describes a solution whose solute concentration is higher than the solute concentration inside a cell
hypha a nonreproductive filament of a fungus
hypocotyl the portion of the stem of a plant embryo that is between the cotyledons and the embryonic root
hypoglycemia a condition in which the concentration of glucose in the blood is very low
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
hypothesis a testable idea or explanation that leads to scientific investigation
hypothyroidism a condition caused by a deficiency of thyroid hormones and marked by fatigue, weight gain, and sensitivity to cold
hypotonic describes a solution whose solute concentration is lower than the solute concentration inside a cell