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868 terms

All The Vocab You Need To Know For The Bio Regents

posterior part of an arthropod's body
abiotic factor
physical, or nonliving, factor that shapes an ecosystem
abscission layer
layer of cells at the petiole that seals off a leaf from the vascular system
accessory pigment
compound other than chlorophyll that absorbs light at different wavelengths than chlorophyll
acellular slime mold
slime mold that passes through a stage in which its cells fuse to form large cells with many nuclei
compound that forms hydrogen ions (H+) in solution
acid rain
rain containing nitric and sulfuric acids
animal lacking a coelom, or body cavity
a protein that mainly makes up the thin filaments in striations in skeletal muscle cells
action potential
reversal of charges across the cell membrane of a neuron; also called a nerve impulse
activation energy
energy needed to get a reaction started
active immunity
immunity produced by exposure to an antigen, as a result of the immune response
active transport
inherited characteristic that increases an organism's chance of survival
adaptive radiation
uncontrollable dependence on a drug
adenosine triphosphate (ATP)
one of the principal chemical compounds that living things use to store and release energy
attraction between molecules of different substances; in plants, attraction between unlike molecules
process that requires oxygen
age-structure diagram
graph of the numbers of males and females within different age groups of a population
threatening behavior that one animal uses to gain control over another
the practice of farming
air sac
one of several sacs attached to a bird's lungs into which air moves when a bird inhales; allows for the one-way flow of air through the respiratory system
algal bloom
one of a number of different forms of a gene
overreaction of the immune system to antigens
alternation of generations
process in which many algae switch back and forth between haploid and diploid stages of their life cycles
amino acid
compound with an amino group (−NH2) on one end and a carboxyl group (−COOH) on the other end
amniotic egg
egg composed of shell and membranes that create a protected environment in which the embryo can develop out of the water
amoeboid movement
type of locomotion used by amoebas
vertebrate that, with some exceptions, lives in water as a larva and on land as an adult, breathes with lungs as an adult, has moist skin that contains mucus glands, and lacks scales and claws
enzyme in saliva that breaks the chemical bonds in starches
process that does not require oxygen
anal pore
region of the cell membrane of a ciliate where waste-containing food vacuoles fuse and are then emptied into the environment
flowering plant; bears its seeds within a layer of tissue that protects the seed
kingdom of multicellular eukaryotic heterotrophs whose cells do not have cell walls
flowering plant that completes a life cycle within one growing season
flower structure in which haploid male gametophytes are produced
male reproductive structure in some algae and plants
primate group made up of humans, apes, and most monkeys
compound that blocks the growth and reproduction of bacteria
protein that helps destroy pathogens
substance that triggers an immune response
opening through which wastes leave the digestive tract
large blood vessel in mammals through which blood travels after it leaves the left ventricle
aphotic zone
permanently dark layer of the oceans below the photic zone
apical dominance
phenomenon in which the closer a bud is to the stem's tip, the more its growth is inhibited
apical meristem
group of undifferentiated cells that divide to produce increased length of stems and roots
structure, such as a leg or antenna, that extends from the body wall
the raising of aquatic organisms for human consumption
domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan
kingdom of unicellular prokaryotes whose cell walls do not contain peptidoglycan
specialized cell in a sponge that makes spicules
female reproductive structure in some plants, including mosses and liverworts
large blood vessel that carries blood from the heart to the tissues of the body
artificial selection
haploid spore produced within the ascus of ascomycetes
structure within the fruiting body of an ascomycete in which two nuclei of different mating types fuse
asexual reproduction
process by which a single parent reproduces by itself
chronic respiratory disease in which the air passageways become narrower than normal
basic unit of matter
ATP synthase
chromosome that is not a sex chromosome
substance produced in the tip of a seedling that stimulates cell elongation
rod-shaped prokaryote
domain of unicellular prokaryotes that have cell walls containing peptidoglycans
virus that infects bacteria
tree structure that includes all tissues outside the vascular cambium, including phloem, the cork cambium, and cork
compound that produces hydroxide ions (OH+) in solution
base pairing
spore in basidiomycetes that germinates to produce haploid primary mycelia
spore-bearing structure of a basidiomycete
behavioral isolation
form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding
organisms that live attached to or near the ocean floor
flowering plant that completes its life cycle in two years
bilateral symmetry
body plan in which only a single, imaginary line can divide the body into two equal halves; characteristic of worms, arthropods, and chordates
binary fission
"type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells
binocular vision
ability to merge visual images from both eyes, which provides depth perception and a three-dimensional view of the world
binomial nomenclature
classification system in which each species is assigned a two-part scientific name
biological diversity; the sum total of the variety of organisms in the biosphere
biogeochemical cycle
biological magnification
increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web
science that seeks to understand the living world
total amount of living tissue within a given trophic level
group of ecosystems that have the same climate and dominant communities
biotic factor
biological influence on organisms within an ecosystem
term used to refer to two-footed locomotion
endothermic animal that has an outer covering of feathers, two legs covered with scales that are used for walking or perching, and front limbs modified into wings
thin, flattened section of a plant leaf that collects sunlight
hollow ball of cells formed when a zygote undergoes a series of divisions
bone marrow
soft tissue inside the cavities within bones
book lung
organ that has layers of respiratory tissue that is used by some terrestrial arthropods for the exchange of gases
Bowman's capsule
brain stem
structure that connects the brain and spinal cord; includes the medulla oblongata and the pons
passageway leading from the trachea to a lung
nonvascular plant; examples are mosses and their relatives
plant structure containing undeveloped tissue that can produce new stems and leaves
asexual process by which yeasts increase in number; process of attaching a bud to a plant to produce a new branch
weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH
term used by scientists to measure the energy stored in foods; 1000 calories
Calvin cycle
dense covering formed by the leafy tops of tall rain forest trees
smallest blood vessel; brings nutrients and oxygen to the tissues and absorbs carbon dioxide and waste products
capillary action
tendency of water to rise in a thin tube
outer protein coat of a virus
in crustaceans, the part of the exoskeleton that covers the cephalothorax; in turtles and tortoises, the dorsal part of the shell
chemical compound known to cause cancer
organism that obtains energy by eating animals
innermost part of a flower that produces the female gametophytes
carrying capacity
Casparian strip
waterproof strip that surrounds plant endodermis cells
group of individual insects specialized to perform particular tasks, or roles
substance that speeds up the rate of a chemical reaction
cell body
cell culture
cell cycle
series of events that cells go through as they grow and divide
cell division
process by which a cell divides into two new daughter cells
cell fractionation
cell membrane
cell specialization
cell theory
cell wall
cell-mediated immunity
immunity against abnormal cells and pathogens inside living cells
cellular respiration
cellular slime mold
slime mold whose individual cells remain separated during every phase of the mold's life cycle
area where the chromatids of a chromosome are attached
concentration of sense organs and nerve cells at the front of an animal's body
region of the brain that coordinates body movements
cerebral cortex
outer layer of the cerebrum of a mammal's brain; center of thinking and other complex behaviors
cerebrospinal fluid
area of the brain responsible for all voluntary activities of the body
one of the first pair of legs of decapods
chemical bond
link that holds together atoms in compounds
chemical reaction
process that changes one set of chemicals into another set of chemicals
organism that must take in organic molecules for both energy and carbon
principal pigment of plants and other photosynthetic organisms; captures light energy
specialized cell in sponges that uses a flagellum to move a steady current of water through the sponge
member of the phylum Chordata; animal that has, for at least some stage of its life, a dorsal hollow nerve cord, a notochord, pharyngeal pouches, and a muscular tail
one of two identical "sister" parts of a duplicated chromosome
"threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next
short hairlike projection similar to a flagellum; produces movement in many cells
circadian rhythm
behavioral cycle that occurs in a daily pattern
diagram that shows the evolutionary relationships among a group of organisms
group of similar orders
classical conditioning
learning process in which an animal makes a mental connection between a stimulus and some kind of reward or punishment
a muscular cavity at the end of the large intestine through which digestive wastes, urine, and eggs or sperm leave the body
closed circulatory system
system in which blood is contained within a network of blood vessels
stinging cell of cnidarians; used for defense and to capture prey
coastal ocean
marine zone that extends from the low-tide mark to the end of the continental shelf
spherical prokaryote
fluid-filled part of the inner ear; sends nerve impulses to the brain through the cochlear nerve
fluid-filled body cavity lined with mesoderm
attraction between molecules of the same substance
type of ground tissue cell with a strong, flexible cell wall; helps support larger plants
common descent
principle that all living things were derived from common ancestors
passing of information from one organism to another
assemblage of different populations that live together in a defined area
companion cell
phloem cell that surrounds sieve tube elements
competitive exclusion principle
ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time
complete metamorphosis
compound light microscope
in gymnosperms, a seed-bearing structure; in the retina of the eye, a photoreceptor that responds to light of different colors, producing color vision
tiny fungal spore that forms at the tips of specialized hyphae in ascomycetes
term used to refer to trees that produce seed-bearing cones and have thin leaves shaped like needles
form of sexual reproduction in which paramecia and some prokaryotes exchange genetic information
connective tissue
contractile vacuole
controlled experiment
controlled variable
factor in an experiment that a scientist purposely keeps the same
convergent evolution
coral reef
diverse and productive environment named for the coral animals that make up its primary structure
cork cambium
lateral meristematic tissue that produces the outer covering of stems
corpus luteum
name given to a follicle after ovulation because of its yellow color
spongy layer of ground tissue just inside the epidermis of a root
first leaf or first pair of leaves produced by the embryo of a seed plant
type of behavior in which an animal sends out stimuli—such as sounds, visual displays, or chemicals—in order to attract a member of the opposite sex
covalent bond
bond formed by the sharing of electrons between atoms
in earthworms, part of the digestive system in which food can be stored; in birds, structure at the lower end of the esophagus in which food is stored and moistened
process in which homologous chromosomes exchange portions of their chromatids during meiosis
in plants, a thick waxy layer on exposed outer surfaces of cells that protects them against water loss and injury
division of the cytoplasm during cell division
plant hormone produced in growing roots and in developing fruits and seeds
"material inside the cell membrane—not including the nucleus
evidence; information gathered from observations
term used to refer to a tree that sheds its leaves during a particular season each year
organism that breaks down and obtains energy from dead organic matter
destruction of forests
demographic transition
scientific study of human populations
extension of the cell body of a neuron that carries impulses from the environment or from other neurons toward the cell body
conversion of nitrates into nitrogen gas
density-dependent limiting factor
limiting factor that depends on population size
density-independent limiting factor
limiting factor that affects all populations in similar ways, regardless of population size
deoxyribonucleic acid (DNA)
nucleic acid that contains the sugar deoxyribose
dependent variable
drug that decreases the rate of functions regulated by the brain
derived character
characteristic that appears in recent parts of a lineage, but not in its older members
inner layer of the skin
descent with modification
organism that feeds on plant and animal remains and other dead matter
particles of organic material that provide food for organisms at the base of an estuary's food web
"animal whose anus is formed from the blastopore of a blastula
diabetes mellitus
condition that occurs when the pancreas produces too little insulin, resulting in an increase in the level of blood glucose
large, flat muscle at the bottom of the chest cavity that helps with breathing
angiosperm whose seeds have two cotyledons
process in which cells become specialized in structure and function
directional selection
disruptive selection
DNA fingerprinting
DNA polymerase
most inclusive taxonomic category; larger than a kingdom
period of time during which a plant embryo is alive but not growing
double fertilization
fertilization in angiosperms, in which two distinct fertilization events take place between the male and female gametophytes
any substance, other than food, that causes a change in the structure or function of the body
drug abuse
intentional misuse of any drug for nonmedical purposes
ecological pyramid
diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web
ecological succession
gradual change in living communities that follows a disturbance
scientific study of interactions among organisms and between organisms and their environment
collection of all the organisms that live in a particular place, together with their nonliving environment
ecosystem diversity
variety of habitats, living communities, and ecological processes in the living world
outermost germ layer of most animals; gives rise to outer layer of the skin, sense organs, and nerves
animal that relies on interactions with the environment to help it control body temperature
electron microscope
electron transport chain
substance consisting entirely of one type of atom
organism in its early stage of development
embryo sac
female gametophyte within the ovule of a flowering plant
movement of individuals out of an area
disease in which the tissues of the lungs lose elasticity, making breathing very difficult
endangered species
species whose population size is rapidly declining and will become extinct if the trend continues
endocrine gland
gland that releases its secretions directly into the bloodstream
innermost germ layer of most animals; develops into the linings of the digestive tract and much of the respiratory system
layer of cells that completely encloses vascular tissue
endoplasmic reticulum
structural support located inside the body of an animal
food-rich tissue that nourishes a seedling as it grows
type of spore formed when a bacterium produces a thick internal wall that encloses its DNA and a portion of its cytoplasm
endosymbiotic theory
protein that acts as a biological catalyst
epidermal cell
outer layer of the skin
plant that is not rooted in soil but instead grows directly on the body of another plant
epithelial tissue
tissue that covers the surface of the body and lines internal organs
when the concentration of a solute is the same throughout a solution
food tube connecting the mouth to the stomach
wetlands formed where rivers meet the ocean
plant hormone that stimulates fruits to ripen
kingdom of unicellular prokaryotes whose cell walls are made up of peptidoglycan
organism whose cells contain nuclei
process by which water changes from a liquid into an atmospheric gas
evolutionary classification
method of grouping organisms together according to their evolutionary history
exocrine gland
gland that releases its secretions through tubelike structures called ducts
process by which a cell releases large amounts of material
expressed sequence of DNA; codes for a protein
exponential growth
external fertilization
process in which eggs are fertilized outside the female's body
term used to refer to a species that has died out
disappearance of a species from all parts of its geographical range
extracellular digestion
process in which food is broken down outside the cells in a digestive tract
facilitated diffusion
movement of specific molecules across cell membranes through protein channels
facultative anaerobe
organism that can survive with or without oxygen
Fallopian tube
one of two fluid-filled tubes in human females through which an egg passes after its release from an ovary
group of genera that share many characteristics
lipid; made up of fatty acids and glycerol; protects body organs, insulates body, and stores energy in the body
structure made mostly of protein that develops from a pit in a bird's skin
feedback inhibition
process in which the product or result stops or limits the process
process by which cells release energy in the absence of oxygen
fetal alcohol syndrome
group of birth defects caused by the effects of alcohol on a fetus
name given to a human embryo after eight weeks of development
elevated body temperature that occurs in response to infection
fibrous root
in algae, a long threadlike colony formed by many green algae; in plants, a long, thin structure that supports an anther
process by which a liquid or gas passes through a filter to remove wastes
aquatic vertebrate characterized by paired fins, scales, and gills
form of asexual reproduction in which an organism splits into two, and each half grows new parts to become a complete organism
ability of an organism to survive and reproduce in its environment
flame cell
seed-bearing structure of an angiosperm
food chain
series of steps in an ecosystem in which organisms transfer energy by eating and being eaten
food vacuole
small cavity in the cytoplasm of protists that temporarily stores food
food web
muscular part of a mollusk
preserved remains or evidence of an ancient organism
fossil record
information about past life, including the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived
founder effect
frameshift mutation
mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide
large leaf of a fern
wall of tissue surrounding an angiosperm seed
fruiting body
slender reproductive structure that produces spores and is found in some funguslike protists; reproductive structure of fungus that develops from a mycelium
kingdom composed of heterotrophs; many obtain energy and nutrients from dead organic matter
gamete-producing structure found in black bread mold
specialized cell involved in sexual reproduction
haploid, or gamete-producing, phase of an organism
group of nerve cells
gastrovascular cavity
digestive chamber with a single opening, in which cnidarians, flatworms, and echinoderms digest food
process of cell migration by which a third layer of cells is formed within the cavity of a blastocyst
gel electrophoresis
small cup-shaped structure in liverworts that contains many haploid cells; used for asexual reproduction
group of archaeocytes surrounded by a tough layer of spicules; produced by some sponges
gene map
gene pool
"combined genetic information of all the members of a particular population
genetic diversity
sum total of all the different forms of genetic information carried by all organisms living on Earth today
genetic drift
random change in allele frequencies that occurs in small populations
genetic engineering
process of making changes in the DNA code of living organisms
genetic equilibrium
situation in which allele frequencies remain constant
genetic marker
scientific study of heredity
genetic makeup of an organism
group of closely related species, and the first part of the scientific name in binomial nomenclature
geographic isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
geologic time scale
scale used by paleontologists to represent evolutionary time
germ theory of disease
idea that infectious diseases are caused by microorganisms, or germs
early growth stage of a plant embryo
growth-promoting substance produced by plants
in earthworms, part of the digestive system in which food is ground into smaller pieces; in birds, a muscular organ that helps in the mechanical breakdown of food
global warming
increase in the average temperatures on Earth
small network of capillaries encased in the upper end of a nephron; where the filtration of blood takes place
Golgi apparatus
use of a stem as a scion
response of a plant to the force of gravity
green revolution
the development of highly productive crop strains and the use of modern agricultural techniques to increase yields of food crops
greenhouse effect
guard cell
specialized cell in the epidermis of plants that controls the opening and closing of stomata by responding to changes in water pressure
indentation in one side of a ciliate that allows food to enter the cell
seed plant that bears its seeds directly on the surfaces of cones
the area where an organism lives, including the biotic and abiotic factors that affect it
habitat fragmentation
splitting of ecosystems into small fragments
learning process by which an animal decreases or stops its response to a repetitive stimulus that neither rewards nor harms it
hair follicle
tubelike pocket of epidermal cells that extends into the dermis; cells at the base of hair follicles produce hair
Hardy-Weinberg principle
principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
Haversian canal
older xylem near the center of a woody stem that no longer conducts water
compound that is toxic to plants
organism that obtains energy by eating only plants
individual that has both male and female reproductive organs
chemical released by activated mast cells that increases the flow of blood and fluids to the surrounding area
protein molecule around which DNA is tightly coiled in chromatin
process by which organisms maintain a relatively stable internal environment
primate that walks upright, has opposable thumbs, and possesses a large brain; only living members are humans
anthropoid group that includes apes and humans
homologous structures
structures that have different mature forms in different organisms but develop from the same embryonic tissues
substance produced in one part of an organism that affects another part of the same organism
hox genes
series of genes that controls the differentiation of cells and tissues in an embryo
humoral immunity
immunity against antigens and pathogens in the body fluids
material formed from decaying leaves and other organic matter
offspring of crosses between parents with different traits
hydrostatic skeleton
layers of circular and longitudinal muscles, together with the water in the gastrovascular cavity, that enable movement
tiny filament that makes up a multicellular fungus or a water mold
movement of individuals into an area occupied by an existing population
immune response
the body's specific defenses that attack a disease-causing agent
ability of the body to resist a specific pathogen
process in which a blastocyst attaches itself to the wall of the uterus
learning based on early experience; once imprinting has occurred, the behavior cannot be changed
incomplete dominance
situation in which one allele is not completely dominant over another
incomplete metamorphosis
independent assortment
independent segregation of genes during the formation of gametes
independent variable
index fossil
distinctive fossil used to compare the relative ages of fossils
logical interpretation based on prior knowledge and experience
inflammatory response
nonspecific defense reaction to tissue damage caused by injury or infection
innate behavior
instinct, or inborn behavior; behavior that appears in a fully functional form the first time it is performed
insight learning
also called reasoning; learning process in which an animal applies something it has already learned to a new situation without a period of trial and error
one of a group of proteins that help cells resist viral infection
internal fertilization
process in which eggs are fertilized inside the female's body
region between nodes on plant stems
period of the cell cycle between cell divisions
intracellular digestion
process in which food is digested inside cells
sequence of DNA that is not involved in coding for a protein
invasive species
plants and animals that have migrated to places where they are not native
animal that does not have a backbone or vertebral column
atom that has a positive or negative charge
ionic bond
when the concentration of two solutions is the same
atom of an element that has a number of neutrons different from that of other atoms of the same element
place where one bone attaches to another
photograph of chromosomes grouped in order in pairs
kelp forest
coastal ocean community named for its dominant organism—kelp, a giant brown alga
tough, fibrous protein found in skin
large taxonomic group, consisting of closely related phyla
Koch's postulates
series of guidelines used to identify the microorganism that causes a specific disease
Krebs cycle
system of communication that combines sounds, symbols, or gestures according to a set of rules about word order and meaning
large intestine
immature stage of an organism that looks different from the adult form
structure in the throat containing the vocal cords
lateral bud
meristematic area on the side of a stem that gives rise to side branches
lateral line system
sensitive receptor system that enables fish to detect gentle currents and vibrations in the water
photosynthetic organ that contains one or more bundles of vascular tissue
alterations in behavior as a result of experience; also called acquired behavior
transparent object behind the iris that changes shape to help adjust the eye's focus to see near or distant objects
symbiotic association between a fungus and a photosynthetic organism
strip of tough connective tissue that holds bones together at a joint
light-dependent reactions
substance in vascular plants that makes cell walls rigid
limiting factor
factor that causes the growth of a population to decrease
limiting nutrient
lipid bilayer
logistic growth
growth pattern in which a population's growth rate slows or stops following a period of exponential growth
long-day plant
plant that flowers when days are long
loop of Henle
section of the nephron tubule that conserves water and minimizes the volume of urine
fluid lost by the blood into surrounding tissue
type of white blood cell that produces antibodies that help destroy pathogens
lysogenic infection
process by which a virus embeds its DNA into the DNA of the host cell and is replicated along with the host cell's DNA
lytic infection
process in which a virus enters a cell, makes a copy of itself, and causes the cell to burst
the larger of a ciliate's two nuclei, contains multiple copies of most of the genes that the cell needs in its day-to-day existence
Malpighian tubule
mammary gland
gland in mammals that produces milk to nourish the young
mouthpart adapted for biting and grinding food
mangrove swamp
coastal wetland dominated by mangroves, salt-tolerant woody plants
manipulated variable
thin layer of tissue that covers most of a mollusk's body
mammal which bears live young that complete their development in an external pouch
mass extinction
medulla oblongata
area of the brain that controls the functioning of many internal organs
motile stage of the life cycle of a cnidarian that has a bell-shaped body
dark-brown pigment found in skin
menstrual cycle
cycle during which an egg develops and is released from an ovary and the uterus is prepared to receive a fertilized egg
phase of the menstrual cycle during which the lining of the uterus, along with blood and the unfertilized egg, is discharged through the vagina
cluster of tissue that is responsible for continuing growth throughout a plant's lifetime
meristematic tissue
plant tissue found only in the tips of shoots and roots; responsible for plant growth
middle germ layer of most animals; gives rise to muscles and much of the circulatory, reproductive, and excretory systems
specialized ground tissue that makes up the bulk of most leaves; performs most of a plant's photosynthesis
messenger RNA (mRNA)
metric system
microscopic fossil
the smaller of a ciliate's two nuclei; contains a "reserve copy" of all of the cell's genes
periodic movement and return of animals from one place to another
inorganic nutrient the body needs, usually in small amounts
part of eukaryotic cell division during which the cell nucleus divides
molecular clock
model that uses DNA comparisons to estimate the length of time that two species have been evolving independently
smallest unit of most compounds
angiosperm whose seeds have one cotyledon
farming strategy in which large fields are planted with a single crop, year after year
single sugar molecule
egg-laying mammal
multiple alleles
three or more alleles of the same gene
muscle tissue
"tissue that controls the internal movement of materials in the body, as well as external movement
change in a DNA sequence that affects genetic information
symbiotic relationship in which both species benefit from the relationship
many hyphae tangled together into a thick mass; comprises the bodies of multicellular fungi
symbiotic association of plant roots and fungi
myelin sheath
insulating membrane surrounding the axon in some neurons
NAD+ (nicotinamide adenine dinucleotide)
electron carrier involved in glycolysis
NADP+ (nicotinamide adenine dinucleotide phosphate)
natural selection
stinging structure within each cnidocyte of a cnidarian that is used to poison or kill prey
excretory organ of an annelid that filters fluid in the coelom
"blood-filtering unit in the renal cortex of the kidney
nerve net
loosely organized network of nerve cells that together allow cnidarians to detect stimuli
nervous tissue
neuromuscular junction
point of contact between a motor neuron and a skeletal muscle cell
cell that carries messages throughout the nervous system
chemical used by a neuron to transmit an impulse across a synapse to another cell
development of the nervous system
stimulant drug in tobacco that increases heart rate and blood pressure
nictitating membrane
movable transparent membrane in amphibians located inside the regular eyelid; protects the surface of the eye from damage under water and keeps it moist on land
nitrogen fixation
process of converting nitrogen gas into ammonia
point on a stem where a leaf is attached
error in meiosis in which homologous chromosomes fail to separate
nonrenewable resource
resource that cannot be replenished by natural processes
long supporting rod that runs through a chordate's body just below the nerve cord
nuclear envelope
layer of two membranes that surrounds the nucleus of a cell
nucleic acid
macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus
the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities
chemical substance that an organism requires to live
immature form that lacks functional sex organs and other adult structures
obligate aerobe
organism that requires a constant supply of oxygen in order to live
obligate anaerobe
organism that cannot live in the presence of oxygen
use of one or more of the senses—sight, hearing, touch, smell, and sometimes taste—to gather information
organism that obtains energy by eating both plants and animals
specialized structure formed by hyphae that produces female nuclei
open circulatory system
operant conditioning
learning process in which an animal learns to behave in a certain way through repeated practice, in order to receive a reward or avoid punishment; also called trial-and-error learning
operational definition
description of how a particular variable is to be measured or how a term is to be defined
region of chromosome in an operon to which the repressor binds when the operon is "turned off"
group of genes operating together
opposable thumb
thumb that enables grasping objects and using tools
group of similar families
group of tissues that work together to perform closely related functions
organ system
group of organs that work together to perform a specific function
specialized structure that performs important cellular functions within a eukaryotic cell
large hole at the top of the sponge through which water leaves the sponge
diffusion of water through a selectively permeable membrane
process of bone formation, during which cartilage is replaced by bone
in plants, a flower structure that contains one or more ovules from which female gametophytes are produced; in animals, the female gonad that produces eggs
term used to refer to animals whose eggs hatch outside the mother's body
term used to refer to animals whose young are born alive after developing in eggs inside the mother's body
process in which an egg is released from the ovary
structure in seed cones in which female gametophytes develop
ozone layer
atmospheric layer in which ozone gas is relatively concentrated
small group of cardiac muscle cells in the right atrium that "set the pace" for the heart as a whole; also known as the sinoatrial node
scientist who studies fossils
palisade mesophyll
layer of tall, column-shaped mesophyll cells just under the upper epidermis of a leaf
gland that produces hormones that regulate blood sugar; produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids; and produces sodium bicarbonate, a base that neutralizes stomach acid
organism that lives within or on another organism and harms that organism by feeding on it
type of ground-tissue cell with a thin cell wall and large central vacuole
passive immunity
short-term immunity caused when antibodies produced by other animals for a pathogen are injected into the body
disease-causing agent
chart that shows the relationships within a family
pair of mouthparts in chelicerates that are usually modified to grab prey
cell membrane in euglenas
external male reproductive organ
flowering plant that lives for more than two years
unit of time into which eras are subdivided
tough layer of connective tissue surrounding a bone
rhythmic muscular contractions that squeeze food through the esophagus into the stomach
layer of permanently frozen subsoil in the tundra
brightly colored structure just inside the sepals; attracts insects and other pollinators to a flower
thin stalk by which a leaf blade is attached to a stem
pH scale
white blood cell that engulfs and digests foreign cells
pharyngeal pouch
one of a pair of structures in the throat (pharynx) region of a chordate
physical characteristics of an organism
photic zone
well-lit upper layer of the oceans
organism that uses energy from sunlight to convert carbon dioxide and water to carbon compounds
organism that is photosynthetic but needs organic compounds as a carbon source
response of plants to periods of light and darkness
light-collecting units of the chloroplast
tendency of plants to grow toward a source of light
accessory pigment found in red algae that is especially good at absorbing blue light
the study of evolutionary relationships among organisms
group of closely related classes
plant pigment responsible for photoperiodism
population of algae and other small, photosynthetic organisms found near the surface of the ocean and forming part of plankton
light-absorbing molecule
process by which a cell takes in liquid from the surrounding environment
pioneer species
first species to populate an area during primary succession
parenchyma cells inside the ring of vascular tissue in dicot stems
pituitary gland
gland in the base of the skull that secretes nine hormones that directly regulate many body functions and control the actions of several other endocrine glands
tiny, free-floating organisms that occur in aquatic environments
kingdom of multicellular photosynthetic autotrophs that have cell walls containing cellulose
straw-colored fluid that makes up about 55 percent of blood
small circular piece of DNA
structure with many nuclei formed by acellular slime molds
ventral part of a turtle's or tortoise's shell
cell fragment released by bone marrow that helps in blood clotting
point mutation
gene mutation involving changes in one or a few nucleotides
polar zone
cold climate zone where the sun's rays strike Earth at a very low angle
pollen cone
cone in gymnosperms that produces male gametophytes in the form of pollen grains
pollen grain
male gametophyte in seed plants
pollen tube
structure grown by a pollen grain; contains two haploid sperm nuclei
polygenic trait
trait controlled by two or more genes
large compound formed from combinations of many monomers
polymerase chain reaction (PCR)
usually sessile stage of the life cycle of a cnidarian that has a cylindrical body with armlike tentacles
condition in which an organism has extra sets of chromosomes
large macromolecule formed from monosaccharides
population density
number of individuals per unit of area
interaction in which one organism captures and feeds on another organism
predator-prey relationship
mechanism of population control in which a population is regulated by predation
term used to refer to a long tail that can grasp branches
pressure-flow hypothesis
hypothesis that considers plants in terms of where they produce and use materials from photosynthesis
primary growth
type of plant growth that occurs at the tips of roots and shoots
primary productivity
rate at which organic matter is created by producers in an ecosystem
primary succession
succession that occurs on surfaces where no soil exists
infectious particle made up of protein rather than RNA or DNA
likelihood that a particular event will occur
organism that can capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotroph
element or compound produced by a chemical reaction
one of the segments that make up most of a tapeworm's body
unicellular organism lacking a nucleus
the viral DNA that is embedded in the host cell's DNA
with few exceptions, small, nocturnal primate that has large eyes for seeing in the dark
hormonelike modified fatty acid produced by a wide range of cells; generally affects only nearby cells and tissues
proteinoid microsphere
tiny bubble, formed of large organic molecules, that has some characteristics of a cell
any eukaryote that is not a plant, an animal, or a fungus
mass of tangled green filaments in mosses that forms during germination
animal whose mouth is formed from its blastopore
body cavity between the endoderm and mesoderm tissues that is partially lined with mesoderm tissue
period of rapid growth and sexual maturation during which the reproductive system becomes fully functional
pulmonary circulation
pathway of circulation between the heart and the lungs
punctuated equilibrium
pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
Punnett square
diagram showing the gene combinations that might result from a genetic cross
small opening in the middle of the iris through which light enters the eye
radial symmetry
body plan in which body parts repeat around the center of the body; characteristic of sea anemones and sea stars
radioactive dating
tongue-shaped structure used for feeding by snails and slugs
process in which liquid is taken back into a vessel
element or compound that enters into a chemical reaction
recombinant DNA
DNA produced by combining DNA from different sources
quick automatic response to a stimulus
reflex arc
sensory receptor, sensory neuron, motor neuron, and effector that are involved in a quick response to a stimulus
relative dating
relative frequency
number of times an allele occurs in a gene pool compared with the number of times other alleles occur
renewable resource
resource that can regenerate quickly and that is replaceable
copying process by which a cell duplicates its DNA
reproductive isolation
separation of species or populations so that they cannot interbreed and produce fertile offspring
any vertebrate that has dry scaly skin, lungs, and terrestrial eggs with several protective membranes
responding variable
factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also known as a dependent variable
single, specific reaction to a stimulus
resting potential
electrical charge across the cell membrane of a resting neuron
restriction enzyme
enzyme that cuts DNA at a specific sequence of nucleotides
innermost layer of the eye; contains photoreceptors
virus that contains RNA as its genetic information
in fungi, a rootlike hypha that penetrates the surface of an object; in mosses, a long, thin cell that anchors the moss to the ground and absorbs water and minerals from the surrounding soil
creeping or underground stem in ferns
ribonucleic acid (RNA)
single-stranded nucleic acid that contains the sugar ribose
ribosomal RNA (rRNA)
type of RNA that makes up the major part of ribosomes
small particle in the cell on which proteins are assembled; made of RNA and protein
risk factor
anything that increases the chance of disease or injury
RNA polymerase
photoreceptor in eye that is sensitive to light but not to colors
underground organ in plants that absorbs water and minerals
root cap
tough structure that protects a root as it forces its way through the soil
root hair
tiny projection from the outer surface, or epidermis, of a root
salt marsh
temperate-zone estuary dominated by salt-tolerant grasses above the low-tide line and by seagrasses under water
organism that obtains food from decaying organic matter
area in plants that surrounds heartwood and is active in fluid transport
type of ground-tissue cell with an extremely thick, rigid cell wall that makes ground tissue tough and strong
head of an adult tapeworm; can contain suckers or hooks
external sac containing the testes
secondary growth
pattern of plant growth in which stems increase in width
secondary succession
succession following a disturbance that destroys a community without destroying the soil
embryo of a living plant that is encased in a protective covering and surrounded by a food supply
seed coat
seed cone
cone that produces female gametophytes
separation of alleles during gamete formation
selective breeding
semicircular canal
one of three structures within the inner ear that help monitor the position of the body
seminiferous tubule
one of hundreds of tiny tubules in the testes in which sperm are produced
sensory receptor
neuron that reacts to a specific stimulus, such as light or sound, by sending impulses to other neurons and eventually to the central nervous system
outermost circle of flower parts that encloses a bud before it opens and protects the flower while it is developing
internal wall between the segments of an annelid's body
bristle attached to the segments of many annelids
sex chromosome
one of two chromosomes that determine an individual's sex; females have two X chromosomes; males have one X chromosome and one Y chromosome
sex-linked gene
gene located on the X or Y chromosome
sexual reproduction
sexually transmitted disease (STD)
disease spread from one person to another during sexual contact
short-day plant
plant that flowers when daylight is short
sieve tube element
phloem cell that is joined end-to-end to similar cells to form a continuous sieve tube
single-gene trait
trait controlled by a single gene that has two alleles
tubelike structure through which water enters and leaves a mollusk's body
small intestine
digestive organ in which most chemical digestion takes place
soil erosion
wearing away of surface soil by water and wind
substance that is dissolved in a solvent to make a solution
substance in which a solute is dissolved to form a solution
cluster of sporangia on the underside of a fern frond
specialized cell
cell that is uniquely suited to performing a particular function
formation of new species
group of similar organisms that can breed and produce fertile offspring
species diversity
number of different species in the biosphere
spike-shaped structure that makes up the skeletons of harder sponges; made of either chalklike calcium carbonate or glasslike silica
fanlike microtubule structure that helps separate the chromosomes during mitosis
organ in spiders that contains silk glands
spiral or corkscrew-shaped prokaryote
spongy mesophyll
loose tissue beneath the palisade layer of a leaf; has many air spaces between its cells
spontaneous generation
hypothesis (disproven) stating that life could arise from nonliving matter
specialized hyphae where sporangia are found
structure in ferns and some fungi that contains spores
haploid reproductive cell
diploid, or spore-producing, phase of an organism
stabilizing selection
supporting structure that connects roots and leaves and carries water and nutrients between them
drug that speeds up the actions regulated by the nervous system
a signal to which an organism responds
in fungi, a stemlike hypha that runs along the surface of an object; in plants, a long, trailing stem that produces roots when it touches the ground
opening in the underside of a leaf that allows carbon dioxide and oxygen to diffuse into and out of the leaf
large muscular sac that continues the mechanical and chemical digestion of food
region outside the thylakoid membranes in chloroplasts
struggle for existence
competition among members of a species for food, living space, and the other necessities of life
narrow stalk of the carpel in a flower
subcutaneous fat
layer of fat cells beneath the skin that helps conserve body heat
reactant of an enzyme-catalyzed reaction
survival of the fittest
mixture of water and nondissolved materials
sustainable development
using natural resources at a rate that does not deplete them
swim bladder
internal gas-filled organ in many bony fishes that adjusts their buoyancy
flipperlike appendages used by decapods for swimming
relationship in which two species live closely together
location at which a neuron can transfer an impulse to another cell
systemic circulation
primary root found in some plants that grows longer and thicker than other roots
target cell
cell that has a receptor for a particular hormone
taste bud
sense organ that detects the flavor of a substance
group or level of organization into which organisms are classified
discipline of classifying organisms and assigning each organism a universally accepted name
fourth and final phase of mitosis, during which the chromosomes begin to disperse into a tangle of dense material
temperate zone
moderate climate zone between the polar zones and the tropics
temporal isolation
form of reproductive isolation in which two populations reproduce at different times
tough connective tissue that joins skeletal muscles to bones
specific area occupied and protected by an animal or group of animals
male gonad that produces sperm
structure containing 4 chromatids that forms during meiosis
brain structure that receives messages from the sense organs and relays the information to the proper region of the cerebrum for further processing
well-tested explanation that unifies a broad range of observations
response of plants to touch
minimum level of a stimulus required to activate a neuron
saclike photosynthetic membrane found in chloroplasts
group of similar cells that perform a particular function
organism's capacity to grow or thrive when subjected to an unfavorable environmental factor
windpipe; tube through which air moves
tracheal tube
hollow plant cell in xylem tissue with thick cell walls that resist pressure
specific characteristic that varies from one individual to another
transfer RNA (tRNA)
decoding of a mRNA message into a polypeptide chain
loss of water from a plant through its leaves
small, bottle-shaped structure used for defense by paramecia
tiny cellular projection on the surfaces of some leaves that helps protect the leaf and also gives it a fuzzy appearance
free-swimming larval stage of an aquatic mollusk
trophic level
step in a food chain or food web
tropical zone
warm climate zone that receives direct or nearly direct sunlight year round
response of a plant to an external stimulus
tube foot
suction-cuplike structure attached to radial canals of echinoderms; used to walk and to open shells
mass of growing tissue
tympanic membrane
eardrum of amphibians inside the skull; vibrates in response to sound, allowing hearing
layer in a rain forest formed by shorter trees and vines
tube that carries urine from the kidney to the urinary bladder
urinary bladder
saclike organ in which urine is stored before being excreted
injection of a weakened or mild form of a pathogen to produce immunity
a preparation of weakened or killed pathogens
cell organelle that stores materials such as water, salts, proteins, and carbohydrates
in the human female reproductive system, a canal that leads from the uterus to the outside of the body
flap of connective tissue between an atrium and a ventricle, or in a vein, that prevents backflow of blood
van der Waals forces
factor in an experiment that can change
vas deferens
tube that carries sperm from the epididymis to the urethra
vascular bundle
plant stem structure that contains xylem and phloem tissue
vascular cambium
lateral meristematic tissue that produces vascular tissues and increases the thickness of the stem over time
vascular cylinder
central region of a root that includes the vascular tissue—xylem and phloem
vascular tissue
type of plant tissue specialized to conduct water and nutrients throughout a plant
animal that carries pathogens from person to person
vegetative reproduction
method of asexual reproduction used by many flowering plants
lower chamber of the heart that pumps blood out of the heart
individual segment of the backbone; encloses and protects the spinal cord
animal that has a vertebral column, or backbone
vessel element
in angiosperms, xylem cell that forms part of a continuous tube through which water can move
vestigial organ
organ that serves no useful function in an organism
single-stranded RNA molecule that has no surrounding capsids
particle made up of nucleic acid, protein, and in some cases lipids that can replicate only by infecting living cells
visceral mass
area beneath the mantle of a mollusk that contains the internal organs
organic molecule that helps regulate body processes
term used to refer to animals that bear live young that are nourished directly by the mother's body as they develop
water vascular system
condition of Earth's atmosphere at a particular time and place
plant that lives in the desert biome
vascular tissue that carries water upward from the roots to every part of a plant
prominent horizontal banding of organisms that live in a particular habitat
tiny animals that form part of the plankton
spore case
resting spore that contains zygotes formed during the sexual phase of a mold's life cycle
fertilized egg