10Th Chem T

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tadpole the aquatic, fishlike larva of a frog or toad

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tadpole

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taiga a region of evergreen, coniferous forest below the arctic and subarctic tundra regions

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taiga

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talus an accumulation of weathered and broken rock fragments at the base of a mountain slope

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talus

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tangential acceleration the acceleration of an object that is tangent to the object’s circular path

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tangential acceleration

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tangential speed the speed of an object that is tangent to the object’s circular path

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tangential speed

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tapeworm one of a variety of segmented, parasitic flatworms

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tapeworm

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taproot a root that develops from the radicle of a plant embryo, grows vertically downward, and forms branches called lateral roots

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taproot

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tar the residue from the burning of cigarette tobacco, which contains many aromatic compounds that are carcinogens

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tar

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target cell a specific cell to which a hormone is directed to produce a specific effect

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target cell

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taste bud one of many oval concentrations of sensory nerve endings on the tongue, palate, and pharynx

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taste bud

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taxonomy the science of describing, naming, and classifying organisms

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taxonomy

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T cell a cell that derives from the thymus and that participates in many immune reactions mediated by cells

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T cell

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technology the application of science for practical purposes; the use of tools, machines, materials, and processes to meet human needs

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technology

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tectonic plate a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle; also called lithospheric plate

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tectonic plate

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telecommunication the sending of visible or audible information by electromagnetic means

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telecommunication

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teleost a group of ray-finned fishes that have a caudal fin, scales, and a swim bladder; the largest group of bony fishes

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teleost

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telescope an instrument that collects electromagnetic radiation from the sky and concentrates it for better observation

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telescope

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telophase the final stage of mitosis or meiosis, during which a nuclear membrane forms around each set of new chromosomes

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telophase

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telson the unpaired, terminal abdominal segment of crustaceans

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telson

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temperate describes a nonvirulent virus that rarely causes lysis in host cells; also moderate, not subject to prolonged extremes of hot or cold

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temperate

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temperate deciduous forest a forest (or biome) that is characterized by trees that shed their leaves in the fall

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temperate deciduous forest

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temperate grassland a community (or biome) that is dominated by grasses, has few trees, and is characterized by cold winters and rainfall that is intermediate between that of a forest and a desert

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temperate grassland

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temperate rain foresta forest community (or biome), characterized by cool, humid weather and abundant rainfall, where tree branches are draped with mosses, tree trunks are covered with lichens, and the forest floor is covered with ferns

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temperate rain forest

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temperate zone the climate zone between the Tropics and the polar zone

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temperate zone

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temperature a measure of how hot (or cold) something is; specifically, a measure of the average kinetic energy of the particles in an object

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temperature

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temperature inversion the atmospheric condition in which warm air traps cooler air near Earth's surface

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temperature inversion

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temperature range the difference between the highest and lowest temperatures of a particular period

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temperature range

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tendon a tough connective tissue that attaches a muscle to a bone or to another body part

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tendon

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tendril an organ of climbing plants that grows in spiral form and wraps around another body to help support the plant

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tendril

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tension-cohesion theory the theory that water moves up the stem of a plant because of the strong attraction between water molecules

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tension-cohesion theory

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tentacle a flexible appendage with which an animal feeds itself, grasps objects, or feels its environment

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tentacle

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terminal moraine an accumulation of glacial drift deposited at the leading edge of a moving glacier

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terminal moraine

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terminal velocity the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity

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terminal velocity

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termination signal a specific sequence of nucleotides that marks the end of a gene

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termination signal

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terrane a piece of lithosphere that has a unique geologic history and that may be part of a larger piece of lithosphere, such as a continent

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terrane

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terrestrial describes an organism that lives on land

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terrestrial

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terrestrial planet one of the highly dense planets nearest to the sun; Mercury, Venus, Mars, and Earth

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terrestrial planet

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territory an area that is occupied by one animal or a group of animals that do not allow other members of the species to enter

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territory

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tertiary amine an organic compound in which all three hydrogen atoms of an ammonia molecule have been replaced by either identical or different groups

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tertiary amine

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test a skeletal covering that some invertebrates secrete or build

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test

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test cross the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

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testes

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testes the primary male reproductive organs, which produce sperm cells and testosterone (singular, testis)

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testes

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testosterone a hormone that regulates male secondary sex characteristics and the production of sperm cells

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testosterone

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tetrad the four chromatids in a pair of homologous chromosomes that come together as a result of synapsis during meiosis

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tetrad

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texture the sizes, shapes, and positions of the grains that make up a rock

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texture

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thalamus the part of the brain that directs incoming sensory and motor signals to the proper region

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thalamus

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describes something that looks like or consists of a simple, undifferentiated plant body

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thalloid

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thallus the body type of an algae, fungus, or plant that is not differentiated into roots, stems, or leaves

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thallus

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thecondont the extinct reptile from which dinosaurs evolved

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thecondont

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theory a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation

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theory

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theory of evolution the theory that states that life on Earth gradually developed from simple to more-complex organisms

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theory of evolution

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therapsid the extinct order of mammal-like reptiles that likely gave rise to mammals

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therapsid

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thermal conduction the transfer of energy as heat through a material

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thermal conduction

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thermal conductivity the rate at which a substance transfers thermal energy

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thermal conductivity

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thermal conductor a material through which energy can be transferred as heat

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thermal conductor

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thermal energy the kinetic energy of a substance's atoms

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thermal energy

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thermal equilibrium the state in which all portions of a thermodynamic system are at a uniform temperature consistent with the system's surroundings

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thermal equilibrium

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thermal expansion an increase in the size of a substance in response to an increase in the temperature of the substance

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thermal expansion

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thermal insulator a material that reduces or prevents the transfer of heat

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thermal insulator

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thermal pollution a temperature increase in a body of water that is caused by human activity and that has a harmful effect on water quality and on the ability of that body of water to support life

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thermal pollution

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thermoacidophile an organism that grows well in a warm, acidic environment

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thermoacidophile

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thermochemistry the branch of chemistry that is the study of the heat changes that accompany chemical reactions and changes of state

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thermochemistry

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thermocline a layer in a body of water in which water temperature drops with increased depth faster than it does in other layers

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thermocline

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thermocouple a device that converts thermal energy into electrical energy

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thermocouple

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thermograph an instrument that measures temperature changes by recording the movement of the bar of a bimetal thermometer

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thermograph

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thermometer an instrument that measures and indicates temperature

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thermometer

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thermoplastic polymer a polymer that can be heated easily and repeatedly to process and soften it

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thermoplastic polymer

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thermoregulation the processes by which the body regulates its internal temperature

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thermoregulation

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thermosetting polymer a polymer that softens when it is initially heated and then hardens and condenses to retain a permanent shape

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thermosetting polymer

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thermosphere the uppermost layer of the atmosphere, in which temperature increases as altitude increases; includes the ionosphere

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thermosphere

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thigmotropism a response of an organism or part of an organism to touch, such as the coiling of a vine around an object

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thigmotropism

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thoracic cavity the part of the human body cavity that is between the neck and the abdomen and that contains the heart and the lungs

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thoracic cavity

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thorax in higher vertebrates, the part of the body between the neck and the abdomen; in other animals, the body region behind the head; in anthropods, the mid-body region

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thorax

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threatened species a species that has been identified to be likely to become endangered in the foreseeable future

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threatened species

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thrust the pushing or pulling force exerted by the engine of an aircraft or rocket

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thrust

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thrust fault a break in a rock structure in which the hanging wall seems to move upward relative to the footwall

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thrust fault

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thunder the sound caused by the rapid expansion of air along an electrical strike

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thunder

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thunderstorm a usually brief, heavy storm that consists of rain, strong winds, lightning, and thunder

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thunderstorm

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thylakoid a membrane system found within chloroplasts that contains the components for photosynthesis

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thylakoid

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thymine one of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA; thymine pairs with adenine

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thymine

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thymosin a hormone that is produced in the thymus gland and that stimulates the differentiation of T cells

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thymosin

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thymus the gland that produces T lymphocytes

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thymus

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thyroid gland an endocrine gland that is located at the base of the neck and that produces secretions important in regulating many aspects of metabolism and mineral balance

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thyroid gland

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thyroid-stimulating hormone a hormone that is produced by the pituitary gland and that stimulates the production and the release of the two thyroid hormones by the thyroid gland (abbreviation, TSH)

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thyroid-stimulating hormone

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thyroxine a thyroid hormone that stimulates body metabolism and helps regulate body growth and development

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thyroxine

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tidal bore a turbulent, wall-like advancing wave of water caused by a very rapid rise of the tide, usually in a long, shallow, and narrowing estuary

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tidal bore

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tidal current the movement of water toward and away from the coast as a result of the rise and fall of the tides

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tidal current

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tidal flat a broad, marshy or barren area of unconsolidated sediment forming a flatland that is covered or uncovered depending on the level of the tides

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tidal flat

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tidal oscillation the slow, rocking motion of ocean water that occurs as the tidal bulges move around the ocean basins

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tidal oscillation

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tidal range the difference in levels of ocean water at high tide and low tide

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tidal range

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tide the periodic rise and fall of the water level in the oceans and other large bodies of water

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tide

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till unsorted rock material that is deposited directly by a melting glacier

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till

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timbre the musical quality of a tone resulting from the combination of all of the harmonics associated with the fundamental frequency

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timbre

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tissue a group of similar cells that perform a common function

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tissue

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tissue culture the technique for growing living cells in an artificial medium

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tissue culture

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Titration a method to determine the concentration of a substance in solution by adding a solution of known volume and concentration until the reaction is completed, which is usually indicated by a change in color

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Titration

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tolerance the condition of drug addiction in which greater amounts of a drug are needed to achieve the desired effect

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tolerance

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tombolo a sand or gravel bar that connects two islands or connects an island to the mainland

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tombolo

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tonsils organs that are small, rounded masses of lymphatic tissue located in the pharynx and in the passage from the mouth to the pharynx

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tonsils

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topographic map a map that shows the surface features of Earth

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topographic map

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topography the size and shape of the land surface features of a region, including its relief

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topography

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topsoil the surface layer of the soil, which is usually richer in organic matter than the subsoil is

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topsoil

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tornado a destructive, rotating column of air that has very high wind speeds and that may be visible as a funnel-shaped cloud

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tornado

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torque a force that causes an object to rotate about a given point

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torque

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torr a unit of pressure equal to 1 mm Hg

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torr

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torsion a process that occurs during the larval development of gastropods and in which the visceral mass twists 180º in relation to the head

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torsion

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the complete reflection that takes place within a substance when the angle of incidence of light striking the surface boundary is less than the critical angle

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total internal reflection

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toxicology the study of toxic substances, including their nature, effects, detection, methods of treatment, and exposure control

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toxicology

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toxin a substance that is produced by one organism and that is poisonous to other organisms

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toxin

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toxoplasmosis a disease that is caused by a sporozoan and that can cause serious harm to fetuses and newborns and flulike symptoms in adults

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toxoplasmosis

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trace fossil a fossilized mark that formed in sedimentary rock by the movement of an animal on or within soft sediment

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trace fossil

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trachea in insects, myriapods, and spiders, one of a network of air tubes; in vertebrates, the tube that connects the larynx to the lungs

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trachea

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tracheid a thick-walled, cylindrical cell with tapered ends that is found in xylem and that provides support and conducts water and nutrients

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tracheid

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trade winds prevailing winds that blow from east to west from 30° latitude to the equator in both hemispheres

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trait

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trait a genetically determined characteristic

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trait

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transcription the process of forming a nucleic acid by using another molecule as a template; particularly the process of synthesizing RNA by using one strand of a DNA molecule as a template

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transcription

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transcription factor an enzyme that is needed to begin and/or continue genetic transcription

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transcription factor

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transduction the transfer of a bacterial gene from one bacterium to another through a bacteriophage

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transduction

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transfer RNA an RNA molecule that transfers amino acids to the growing end of a polypeptide chain during translation

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transfer RNA

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transformation the transfer of genetic material in the form of DNA fragments from one cell to another or from one organism to another

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transformation

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transform boundary the boundary between tectonic plates that are sliding past each other horizontally

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transform boundary

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transformer a device that increases or decreases the voltage of alternating current

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transformer

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transgenic animal an animal into which cloned genetic material has been transferred

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transgenic animal

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transgenic organism an organism that has been transformed by the introduction of novel DNA into its genome

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transgenic organism

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transistor a semiconductor device that can amplify current and that is used in amplifiers, oscillators, and switches

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transistor

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transition element one of the metals that can use the inner shell before using the outer shell to bond

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transition element

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transition interval the range in concentration over which a variation in a chemical indicator can be observed

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transition interval

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transition metal one of the metals that can use the inner shell before using the outer shell to bond

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transition metal

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translation the portion of protein synthesis that takes place at ribosomes and that uses the codons in mRNA molecules to specify the sequence of amino acids in polypeptide chains

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translation

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translocation the movement of a segment of DNA from one chromosome to another, which results in a change in the position of the segment; also the movement of soluble nutrients from one part of a plant to another

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translocation

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translucent describes matter that transmits light but that does not transmit an image

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translucent

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transmission the passing of light or other form of energy through a medium

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transmission

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transmutation the transformation of atoms of one element into atoms of a different element as a result of a nuclear reaction

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transmutation

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transparent describes matter that allows light to pass through with little interference

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transparent

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transpiration the process by which plants release water vapor into the air through stomata; also the release of water vapor into the air by other organisms

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transpiration

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transuranium element a synthetic element whose an atomic number is greater than that of uranium (atomic number 92)

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transuranium element

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transverse wave a wave in which the particles of the medium move perpendicularly to the direction the wave is traveling

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transverse wave

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travertine a hard, compact limestone deposited by solution from surface water or groundwater

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travertine

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trench a long, narrow, and steep depression that forms on the ocean floor as a result of subduction of a tectonic plate, that runs parallel to the trend of a chain of volcanic islands or the coastline of a continent, and that may be as deep as 11 km below sea level; also called an ocean trench or a deep-ocean trench

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trench

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tributary a stream that flows into a lake or into a larger stream

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tributary

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trichinosis a disease that is caused by a parasitic roundworm of the genus Trichinella, that results from eating the larvae in undercooked meat, and that is characterized by diarrhea, fever, abdominal and muscle pain, and affliction of the lungs, nervous system, and heart

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trichinosis

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tricuspid valve the valve that separates the right atrium from the right ventricle and that prevents the blood from flowing backward

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tricuspid valve

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triglyceride a lipid made of three fatty acid molecules and one glycerol molecule

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triglyceride

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triple bond a covalent bond in which two atoms share three pairs of electrons

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triple bond

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triple point the temperature and pressure conditions at which the solid, liquid, and gaseous phases of a substance coexist at equilibrium

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triple point

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triprotic acid an acid that has three ionizable protons per molecule, such as phosphoric acid

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triprotic acid

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trisomy a chromosomal anomaly in which an individual has an extra chromosome in any of the chromosome pairs

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trisomy

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trochophore a free-swimming, ciliated larva of many worms and some mollusks

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trochophore

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Trojan asteroids asteroids that precede or follow Jupiter in its orbit by 60°

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Trojan asteroids

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trophic level one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers

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trophic level

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tropical climatea climate characterized by high temperatures and heavy precipitation during at least part of the year; typical of equatorial regions

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tropical climate

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tropical rain forest a forest or jungle near the equator that is characterized by large amounts of rain and little variation in temperature and that contains the greatest known diversity of organisms on Earth

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tropical rain forest

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tropical zone the region that surrounds the equator and that extends from about 23º north latitude to 23º south latitude

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tropical zone

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tropismthe movement of all or part of an organism in response to an external stimulus, such as light or heat; movement is either toward or away from the stimulus

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tropism

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tropopause the upper limit of the troposphere

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tropopause

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troposphere the lowest layer of the atmosphere, in which temperature drops at a constant rate as altitude increases; the part of the atmosphere where weather conditions exist

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troposphere

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trough the lowest point of a wave

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trough

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true-breeding describes organisms or genotypes that are homozygous for a specific trait and thus always produce offspring that have the same phenotype for that trait

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true-breeding

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true north the direction to the geographic North Pole

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true north

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tsunami a giant ocean wave that forms after a volcanic eruption, submarine earthquake, or landslide

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tsunami

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tube cell the cell of a pollen grain that gives rise to the pollen tube

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tube cell

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tube foot one of many small, flexible, fluid-filled tubes that project from the body of an echinoderm and that are used in locomotion, feeding, gas exchange, and excretion

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tube foot

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tumor a growth that arises from normal tissue but that grows abnormally in rate and structure and lacks a function

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tumor

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tumor suppressor gene a gene that suppresses tumor formation but that, when mutated, causes a loss in cell function, which results in tumor formation

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tumor suppressor gene

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tundra a treeless plain that is located in the Arctic or Antarctic and that is characterized by very low winter temperatures; short, cool summers; and vegetation that consists of grasses, lichens, and perennial herbs

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tundra

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turbidity current a dense current that carries large amounts of sediment through sea water that is less dense

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turbidity current

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turgor pressure the pressure that is exerted on the inside of cell walls and that is caused by the movement of water into the cell

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turgor pressure

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tympanic membrane the eardrum

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tympanic membrane

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tympanum a sound-sensing membrane on the abdomen of an insect

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tympanum

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typhoon a severe tropical cyclone that forms on the western Pacific Ocean and on the China Seas; a hurricane

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typhoon