A neurotransmitter released by neurons to excite an action potential or trigger a muscle to contract.
The evolutionary process by which ancestral forms of an organism are diversified through adaptation to new environments.
The frequency with which a particular allele for a certain characteristic appears among all possible alleles for that characteristic in a population
alternation of generations
The fluctuation between the diploid (sporophyte) and haploid (gametophyte) life stages that occur in plants.
The monomer of a protein. A central carbon attached to an amino group (-NH2), a carboxyl group (-COOH), and a hydrogen atom (-H). The fourth group is variable and defines the amino acid's chemical identity.
A trait that is morphologically and functionally similar to that of a different species but that arose from a distinct, ancestral condition.
A vascular flowering plant in which seeds are enclosed inside protective ovaries, such as fruit or flowers. Angiosperms can be monocots or dicots.
The largest artery in the body; carries oxygenated blood from the left ventricle of the heart.
part of the marine pelagic zone that begins 600 feet below the surface of the ocean; only chemosynthetic organisms, scavengers, and predators are able to survive in this habitat.
vessel that carries blood away from the heart and has thick, elastic, muscular walls that can dilate or contract to control blood pressure within the vessels. Blood in arteries is oxygenated, with the exception of the blood in the pulmonary artery
autonomic nervous system
the involuntary half of the peripheral nervous system; in two antagonistic parts: the sympathetic and parasympathetic nervous systems. Their interactions control smooth and cardiac muscle, glands, and organs and processes such as heartbeat, the movements of the digestive tract, and the contraction of the bladder
an organism that can produce the organic molecules and energy necessary for life through the processes of photosynthesis or chemosynthesis
one in a class of plant hormones that stimulates (among other things) cell elongation, secondary tissue growth, and fruit development
emulsifier of fats secreted by the liver and stored in the gallbladder for release in the small intestine
amount of living matter in a given ecosystem. Because only 10 percent of energy is transferred between trophic levels, the biomass of lower trophic levels is greater than the biomass of subsequent trophic levels: biomass of producers > biomass of primary consumers > biomass of secondary consumers > biomass of tertiary consumers.
particular geographic area with a common climate and characteristic plant and animal life; characterized by specific climax communities
liquid that carries nutrients and oxygen to the cells and carries carbon dioxide and nitrogenous wastes away
rigid structures composed of living cells rooted in a matrix of calcium, phosphate salts, and collagen fibers
lower terrestrial plant (often a moss or liverwort) that lacks a vascular system and is dependent on environmental moisture for reproductive and nutritive functions
asexual reproductive process in which a small portion of the cell membrane and cytoplasm receive a nucleus and pinch off from the parent cell
roughly spherical underground bud containing additional buds that can develop asexually into new plants
light-independent phase of photosynthesis, where carbon dioxide is fixed to a three-carbon compound used to form glucose; ATP and NADH are consumed in this cycle
tiny blood vessels able to branch through the body and deliver oxygen and nutrients to every cell.
maximum number of individuals in a population that can be sustained in a given environment
firm but flexible substance, found in regions of vertebrate skeletons, such as the ribs, that need to bend
process in which the cell burns glucose to create ATP with the aid of oxygen; cells have two different methods of turning food into usable fuel: aerobic respiration and anaerobic respiration
part of the brain that controls all voluntary movement, sensory perception, speech, memory, and creative thought
cycles in which inorganic elements move through the biotic and abiotic aspects of an ecosystem. The two most important chemical cycles are the carbon and nitrogen cycles
synthesizing organic compounds by energy derived from chemical reactions rather than from the energy of the sun
system of organs and blood that brings nutrients and oxygen to cells and carries away wastes.; in higher vertebrates, the system has a pulmonary and systemic circuit; pulmonary circuit carries blood to the lungs to be oxygenated, while the systemic circuit carries oxygenated blood to the body; vertebrates have a closed ______, while arthropods have an open one
combination of plant and animal forms that dominate mature ecological communities. Climax communities are unique and shaped by various factors, including temperature, rainfall, and soil acidity
phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in a heterozygote
animals that are unable to retain heat produced by metabolic activities. Also known as ectothermic. The metabolism of cold-blooded animals is greatly influenced by climate and temperature
many populations that interact in a given geographical locale constitute ecological communities. Communities exhibit particular interactions such as competition, symbiosis, predation, and food relationships; undergo ecological succession
struggle for survival between organisms or populations that use similar resources and occupy similar niches
An organelle often found in protozoa that pumps excess water out of the cell to keep the cell from bursting in a hypotonic environment (like freshwater).
The main component of the cytoplasm. It is a grayish, gel-like liquid containing the nucleus, organelles, and cytoskeleton.
A flowering plant (angiosperm) that possesses two cotyledons during embryonic development. Usually has taproots, flower parts in multiples of fours and fives, and branching veins in leaves.
The progression of plant life and attendant animal life in a given geographic location, from pioneer plant to climax community.
The study of the interactions and relationships of populations with each other and their abiotic environments.
electron transport chain
The final stage of aerobic respiration. The electron transport chain establishes an electrochemical gradient across the inner mitochondrial membrane that powers the synthesis of ATP in oxidative phosphorylation.
Control system of the body that functions by releasing hormones into the bloodstream.
Process by which liquids or small solid particles are taken into a cell in the form of small vesicles that are produced through the invagination of the cell membrane.
Energy in a community can be depicted as a pyramid of food or biomass. The availability of food, biomass, and energy from the trophic level of producers up through each subsequent level on the food web is approximately 10 percent of that available in the previous trophic level.
The organ system that filters blood and removes nitrogenous wastes from the body in the form of urea or uric acid. In humans, the two kidneys are the vital organs of blood filtration. In annelids, nephridia fill the filtering role; Malpighian tubules do the same in arthropods. In humans, other important structures of the system are the ureters, the urinary bladder, and the urethra.
A rigid, chitinous protective structure that surrounds the bodies of arthropods and provides support.
Diffusion of molecules that cannot pass through the cell membrane independently, but rather through permeable protein channels embedded in the membrane. Facilitated diffusion does not require outside energy.
The second stage of anaerobic respiration, which produces the NAD+ necessary for glycolysis. There are two types of fermentation: alcoholic fermentation and lactic acid fermentation. Yeast engage in alcoholic fermentation, while muscle cells lacking oxygen produce lactic acid.
An organ that stores the bile produced by the liver and releases it to the small intestine during digestion.
An artificial form of vegetative propagation in which parts of two young plants are joined together, first by artificial means and then by tissue regeneration.
A process by which components of bacterial cell walls are bound to Gram's stain. Depending on the amount of peptidoglycan in their cell walls, bacteria stain differently and are classified as Gram-negative or Gram-positive.
Epidermal plant cells found in pairs surrounding the stomata of leaves. By increasing or decreasing their size, guard cells regulate gas exchange by opening and closing individual stoma.
A vascular nonflowering plant (commonly known as a conifer) in which seeds are "naked"—collected in a cone and not protected by an ovary. The dispersion of their spermatozoids often relies on wind.
The muscular organ that pumps blood through the circulatory system. Mammals and birds have a four-chambered heart, with a left atrium and ventricle and a right atrium and ventricle. The right half of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left half receives oxygenated blood from the lungs and pumps it to the body.
The genetic transmission of traits from parents to offspring, so that offspring resemble their parents. Traits transmitted this way are called hereditary traits.
Organisms that can only get the organic molecules and energy necessary for life through the consumption of other organic matter. In the food web, all consumers and decomposers are heterotrophs. Heterotrophs can be herbivores, carnivores, or omnivores.
A weak bond between hydrogen and a set of other elements, including oxygen. Hydrogen bonds are a subset of dipole-dipole interactions.
A common biochemical reaction in which the bond between two molecules is split by the addition of a water molecule; breaks down polymers and dimers
A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.
learning that occurs during a sensitive or critical period in the early life of an individual and is irreversible for the length of that period
hormone secreted by the pancreas that reduces blood sugar levels; lack this hormone can result in diabetes
The phase of the eukaryotic cell cycle in which the cell prepares for division, primarily by replicating its DNA. After interphase, the cell enters mitosis.
The most shallow zone in a marine habitat. Periodically dry or wet with the changing tides. Algae, sponges, mollusks, starfish, and crabs inhabit this zone. Also called the littoral zone.
An evolutionary theory (proved false by Darwin) stating that species change over time by the use and disuse of structures and the inheritance of acquired traits.
Behavior that an organism picks up over the course of its life. Three types of learned behavior are habituation, conditioning, and associative learning.
made the first observations of bacteria and protozoa using single-lens microscopes of his own design
Genes that are located close together on the same chromosome. Linked genes will not undergo independent assortment during gamete formation, constituting an exception to the law of independent assortment. Crossing-over will disrupt the linkage of two genes on the same chromosome if they are far enough apart.
A means of returning blood fluid, lymph, that has escaped from capillaries back into the bloodstream. Defended against foreign bodies by lymphocytes.
Part of the brain responsible for the control of involuntary functions such as breathing, cardiovascular regulation, and swallowing.
The internal tissue of a leaf between the epidermal cells; specialized for photosynthesis. Contains the palisade and spongy layer.
Inorganic molecules required by the body to carry out life processes. Important minerals are iron, a necessary component of hemoglobin; iodine, which is essential for making thyroid hormone; and calcium, which is required by the bones and for many cellular processes.
Structures that create movement in an organism by contracting under a stimulus from a neuron. There are three types of muscle: skeletal, which is responsible for voluntary movement; smooth, which is responsible for involuntary movement; and cardiac, which makes up the heart.
An error in the sequence of nucleotides in DNA or RNA that in turn affects the production of proteins. There are two main types of mutations: substitution mutations and frameshift mutations. A substitution mutation occurs when one nucleotide is replaced by another; these mutations can range from ineffectual to drastic, depending on how the new nucleotide changes the protein coded for. Frameshift mutations occur when a nucleotide is either inserted or deleted into the code; these mutations are always drastic and often fatal, since an insertion or deletion will affect every codon in a particular genetic sequence by throwing the entire three-by-three codon frame out of whack.
A structure that speeds the movement of action potentials along the axon of a neuron. The sheath is built of Schwann cells, which wrap themselves around the axon of the neuron, leaving small gaps in between known as the nodes of Ranvier.
An energy-carrying coenzyme produced by glycolysis and the Krebs cycle. NADH carries energy to the electron transport chain, where it is stored in ATP.
The theory, first proposed by Darwin, which holds that organisms produce as many offspring as possible, which compete for limited resources. Organisms' characteristics vary, and certain characteristics will allow organisms to survive and reproduce more effectively. These adaptive characteristics will be more prevalent in subsequent generations. Natural selection is the engine of evolution, choosing the most fit genes to pass from one generation to the next.
Tiny, tubule structures responsible for the filtering of blood in the kidneys of vertebrates.
The medium depth zone of the marine biome. Extends to 600 feet beneath the water's surface and sits on the continental shelf, hundreds of miles from any shore. Algae, crustaceans, and fish inhabit this region.
the unique role a population plays in a community; includes all characteristics that define the way a population exists in a community, from where the members live to what they eat, when they sleep, and how they reproduce.
adenine, thymine, guanine, and cytosine in DNA; RNA is composed of adenine, uracil, guanine, and cytosine
A longitudinal rod of cells that forms in the least developed chordates and in embryonic stages of more developed chordates.
Region near the top of the nasal cavity with chemoreceptors and neurons that inform the sense of smell.
Process by which water naturally travels from an area of high water concentration to low water concentration.
Part of the electron transport chain. A process occurring in the mitochondria that results in the formation of ATP from the flow of electrons across the inner membrane to bind with oxygen.
A digestive organ that releases enzymes into the small intestine. Also an endocrine gland that regulates glucose levels in the blood by the release of insulin or glucagon from specialized cells called islets of Langerhans.
Four small glands embedded on the posterior surface of the thyroid gland. The parathyroid glands produce a hormone that regulates the level of calcium in the bloodstream.
Asexual reproduction in which an unfertilized gamete (usually female) produces female offspring. Parthenogenesis vastly increases the speed at which a population can grow, though it results in a loss of genetic diversity among members of the population.
The open-ocean zone at the greatest depth in a marine habitat. This zone is divided into a photic (down to 600 feet below the water's surface) and aphotic zone.
The rolling motion of smooth muscle that moves food along the alimentary canal. Includes the passage from the esophagus to the stomach, the churning action of the stomach, and the passage through the small intestine.
Vascular tissue composed of cells that are living at maturity; transports the products of photosynthesis throughout the plant body.
Literally, zone with light. The photic zone is part of the marine pelagic zone and extends to 600 feet below the surface of the ocean. Photosynthetic plankton as well as bony fish, sharks, and whales inhabit this zone.
An organism's response to the length of day and night within a 24-hour period (photoperiod); in many plants, this phenomenon determines when flowering occurs.
The process by which plants and other autotrophic organisms convert light energy into organic materials, such as glucose.
A group of interbreeding organisms in a particular locale exhibiting a unique set of characteristics such as patterns of growth and reproductive strategies.
Term that refers to one organism eating another. Predation covers both carnivorous and herbivorous consumption.
Autotrophic organisms such as plants, plankton, and chemosynthetic bacteria that are able to synthesize organic compounds using energy from the sun or chemical reactions. Producers do not have to consume other organisms to attain energy and are the foundation of every food web.
Temporary cytoplasmic protrusions of ameboid cells that function in movement and food uptake by phagocytosis.
The inability of individuals within a species to create offspring with members of any other species
The organ system responsible for the intake of oxygen and diffusion of that gas into the blood and the elimination of carbon dioxide from the body. Important structures of the system are the pharynx, larynx, trachea, bronchi, bronchioles, and lungs. Alveoli in the lungs are the location of gas exchange with the blood. The movement of the muscular diaphragm allows the lungs to inhale and exhale.
The part of a plant beneath the soil; responsible for collecting water and minerals from the soil, storing nutrients, and securing the plant to the ground. Can be fibrous or a taproot.
An outgrowth of a plant root that provides an increased surface area for the absorption of water and dissolved minerals from the soil.
somatic nervous system
One half of the motor system of the peripheral nervous system. Responsible for voluntary, or conscious, movement. Neurons in this system target skeletal muscles and release the neurotransmitter acetylcholine.
The development of a species through evolution. A species forms when its members become reproductively isolated from all other organisms. Speciation can occur through geographic separation that eliminates gene flow or through adaptive radiation.
Usually unicellular and microscopic, spores are produced by protist molds, fungi, and plants and are able to develop into new individuals. Spores are able to survive without food or water for long periods. Most fungi spend part of their life cycle as hyphae and part as spores.
The starting material that will undergo chemical change in a chemical reaction facilitated by an enzyme.
A type of interaction within a community that falls into one of three categories: a parasitic relationship benefits one organism and hurts the other; a commensal relationship benefits one and does not affect the other; a mutualistic relationship benefits both organisms.
The gap between two neurons, spanning the space between the axon of one and the dendrites of the other. In order to pass an impulse across a synapse, neurons must release neurotransmitters.
A group of closely connected and similar cells that cooperate to generate a specific structure or specialized function within an organism.
Steps on a food/biomass pyramid that are defined by organisms within a community that are the same distance from the primary producers in a food web.
Fleshy underground storage structure composed of an enlarged portion of the stem that has on its surface buds capable of producing new plants.
Tissue that produces new vascular cells; lies between the xylem and phloem in dicot stems.
A conductive component (either xylem or phloem) of the vascular system that transports food and nutrients throughout the plant body.
A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.
A blood vessel that carries blood back to the heart. The blood in veins is not oxygenated, with the exception of the pulmonary vein.
Bodily structures that developed in the past but no longer serve any function for an organism.
Fingerlike projections in the small intestine that increase surface area and maximize the absorption of nutrients.
Vascular tissue composed of cells that are dead at maturity; transports water and dissolved minerals upward from the roots to the shoot.
movement of particles against a gradient from low concentration to high concentration; requires expenditure of energy
the process by which certain cells convert pyruvic acid or pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the abscence of oxygen
microscopic air sacs in the lung where diffusion of the respiratory gases oxygen and carbon dioxide occurs
a technique to determine whether an individual plant or animal showing the dominant trait is homozygous dominant or heterozygous
organisms at higher trophic levels have a greater concentration of accumulated toxins stored in their bodies than those at lower trophic levels
natural disasters reduce the size of a population nonselectively, resulting in a loss of genetic variation; the resulting population is much smaller and non representative of the original one
band of muscle at the top of the stomach that keeps acidic food in the stomach from backing up into the esophagus and burning it
female part of a flower that produces the female gametophytes (ova); consists of an ovary, stigma, and style
a limit to the number of individuals that can occupt one area at a particular time (K)
organelles responsible for the division of the cytoplasm in animal cells; consist of 9 triplets of microtubules arranged in a circle
consists of two centrioles at right angles to each other; is important during cell division in animal cells
a type of learning in which one stimulus becomes linked to another through experience
symbiotic relationship in which one organism benefits and one is not affected by the other (+/o)
the theory that states that the continents are floating and moving very slowly; over millions of years seven separate continents formed Pangea
type of evolution where unrelated species occupying the same environment and subjected to similar selective pressures show similar adaptations
process in which homologous chromatids exchange genetic material; increases variation in gametes
process by which molecules are bonded together to form a larger molecule with the removal of water (condensation)
characteristic of proteins that consists of a change in shape that stops the protein from functioning
enzymatic breakdown, hydrolysis, of food so that it is small enough to be assimilated into the body
type of natural selection that is due to changing environmental conditions; one phenotype replaces another in the gene pool
type of natural selection that increases the number of extreme types in a population at the expense of intermediate forms
occurs when a population becomes isolated from the rest of the species and becomes exposed to new selective pressures, causing it to evolve into a new species; homologous structures are evidence of this
electron transport chain
consists of a series of molecules within the cristae membrane of mitochondria that provides the energy to phosphorylate ADP into ATP during oxidative phosphorylation
process that occurs in the nephron where nutrients and wastes diffuse from the glomerulus into Bowman's capsule
fixed action pattern
innate, highly stereotypical behavior which once begun is continued to completion, no matter how useless or silly looking; stimulated by sign stimuli
a small population, which is not representative of the larger population, breaks away from the larger one to colonize a new area; rare alleles may be under- or overrepresented
a single parent organism breaks into parts that regenerate into new individuals; reproduction in sponges, planaria, and sea stars
an error in the DNA in which the entire reading frame is altered; caused by an insertion or deletion
the process by which a blastula develops into a gastrula with the formatino of three embryonic layers
separation by natural barriers (e.g. mounts, rivers) that may cause significant isolation
the anaerobic phase of aerobic respiration; one molecule of glucose breaks apart into two molecuels of pyruvate
the theory that organisms descended from a common ancestor gradually over a long period of time in a linear or branching fashion
membranes within chloroplasts that consist of thylakoid membranes and are the sites of the light-dependent reaction of photosynthesis
carbon dioxide and water vapor in the air absorb much of the infrared radiation reflecting off Earth, causing the average temperature on Earth to rise
gross primary productivity
the amount of energy converted to chemical energy by photosynthesis per unit time in an ecosystem
one of the simplest forms of learning in which an animal comes to ignore a persistent stimulus so it can go about its business
an important chemical in the immune system that triggers vasodilation (enlargement of blood vessels) which increases blood supply to an area; responsible for systems of the common cold in an atempt to rid the body of invaders
the same internal bone structure, although the function of each varies; means that organisms have a common ancestor
a generative inderited disease of the nervous system resulting in certain and early death; the gene that causes it is dominant, and onset is usually in middle age
a mutation where on nucleotide inserts itself into an existing strand; this mutation can cause a frameshift
a chromosoal fragment breaks off an reattaches to its original chromosome but in the reverse orientation
first stage of the aerobic phase of cellular respiration that occurs in the inner matrix of the mitochondria
structures within the villi that line the small intestine and that absorb fatty acids and glycerol into the lymphatic system
lactic acid fermentation
occurs during strenuous exercise when the body cannot keep up with the increased demand for oxygen and pyruvic acid converts to lactic acid, causing fatigue and burning
law of dominance
Mendel's first law that states that when two homozygous organisms for two opposing traisn are corssed, the offspring will be hybrid but will exhibit only the dominant trait
law of independent assortment
a cross that is carried out between two individuals hybrid for two or more traits that are not on the same chromosomes, resulting in the phenotype ratio 9:3:3:1
law of segregation
during the formation of gametes, the traits carried on homologous chromosomes separate
organelle that consists of digestive enzymes and is the principal site of intracellular digestion in the cell
part of photosynthesis that requires light, produces ATP, and releases oxygen
part of photosynthesis that does not require light directly, only the products of the light dependnet reactions; sugar (G3P) is the product
type of cell division for growth and repair that produces two genetically identical daughter cells with the same chromosome number as the parent
net primary productivity
gross primary productivity minus the energy used by the primary producers for respiration
an error that sometimes happens during meiosis in which homologous chromosomes fail to separate as they should
process by which cells continue to differentiate, producing organs from the three embryonic germ layers
where fertilization occurs; after ovulation, the eff moves through the oviduct to the uterus; a.k.a. Fallopian tube
hormone secreted by the poosterior pituitary that stimulates the uterus and causes contractions during labor
two related species that have made similar evolutionary adaptations after their divergence from a common ancestor
femily tree that indicates the phenotype of one trait being studied for every member of a family
the process that occurs during the light-dependent reactions in which water is split to provide electrons to replace those lost by chlorophyll a; oxygen is released
openings in cell walls of plants for the passage of materials from one cell to another
molecules that consits of many monosaccharides joined together; e.g. starch and chitin
theory that proposes that new species appear suddenly after long periods of stasis
band of muscle at the bottom of the stomach that keeps food in the stomach long enough to be digested
in the nephron of the kidneys, a process by which most of the water and solutes that initially entered the tubule during filtration are transported back into the capillaries
the modern technique ot taking DNA from two sources and combining them into one molecule or cell
strucutal RNA that is synthesized in the nucleolus; along with proteins, it makes up the ribosomes
digestive hormone that stimulates the pancreas to release bicarbonate to neutralize acid in the duodenum
process that occurs in the tubule of the nephron, which is the active uptake of molecules that did not get filtered into Bowman's capsule
replicated chromosome consists of two of these, where on is an exact copy of the other
elaborate molecule that sits within neuron membranes and pumps sodium and potassium ions across the membrane
a population whose members have the potential to interbreed in nature andp roduce viable, fertile offspring
amount of heat that must be absorbed in order for 1 gram of a substance to change its temperature by 1 degree Celsius
type of natural selection that eliminates the extremes and favors the more common intermediate forms
substrate level phosphorylation
process by which ATP is produced as a special enzyme moves a phosphate from one molecule to ADP; how energy is produced during glycolysis and the Krebs cycle
system of transport within a plant consisting of openings in cell walls called plasmodesmata
special nonsense nucleotide sequences located at the ends of chromosomes that repeat thousands of times; protect DNA during cell division
theory thats states that cell organelles were once tiny, free-living prokaryotic organisms that took up permanent residence inside larger prokaryotic organisms
specialized membranes that make up the grana in chloroplasts, the site of the light-dependent reactions
occurs in bacteria; the ability to transform themselves by transferring genetic factors from one bacteria cell to another
the process in which the DNA code is translated into an amino acid sequence and a polypeptide is formed; occurs atthe ribosome
having a chromosome in triplicate instead of duplication; down syndrome is caused by this on the 21st chromosome
fingerlike projections that line the small intestine and absorb all nutrients that were previously released from digested food
competition between populations that may drive a population out of a community or push it to evolve a different niche to reduce competition