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420 terms

SAT II Biology

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acetylcholine
A neurotransmitter released by neurons to excite an action potential or trigger a muscle to contract.
actin
Protein filaments that, along with myosin, allow muscles to contract
adaptive radiation
The evolutionary process by which ancestral forms of an organism are diversified through adaptation to new environments.
allelic frequency
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.
amino acid
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.
analogous trait
A trait that is morphologically and functionally similar to that of a different species but that arose from a distinct, ancestral condition.
angiosperm
A vascular flowering plant in which seeds are enclosed inside protective ovaries, such as fruit or flowers. Angiosperms can be monocots or dicots.
anther
Pollen-producing structure at the top of the stamen, the male reproductive organ of flowers.
aorta
The largest artery in the body; carries oxygenated blood from the left ventricle of the heart.
aphotic zone
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.
artery
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
autotroph
an organism that can produce the organic molecules and energy necessary for life through the processes of photosynthesis or chemosynthesis
auxin
one in a class of plant hormones that stimulates (among other things) cell elongation, secondary tissue growth, and fruit development
bile
emulsifier of fats secreted by the liver and stored in the gallbladder for release in the small intestine
biomass
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.
biome
particular geographic area with a common climate and characteristic plant and animal life; characterized by specific climax communities
blood
liquid that carries nutrients and oxygen to the cells and carries carbon dioxide and nitrogenous wastes away
bone
rigid structures composed of living cells rooted in a matrix of calcium, phosphate salts, and collagen fibers
brain
center of the central nervous system; coordinates the processes of the body
bryophyte
lower terrestrial plant (often a moss or liverwort) that lacks a vascular system and is dependent on environmental moisture for reproductive and nutritive functions
budding
asexual reproductive process in which a small portion of the cell membrane and cytoplasm receive a nucleus and pinch off from the parent cell
bulb
roughly spherical underground bud containing additional buds that can develop asexually into new plants
Calvin cycle
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
capillary
tiny blood vessels able to branch through the body and deliver oxygen and nutrients to every cell.
carbon
central element of life
carrying capacity
maximum number of individuals in a population that can be sustained in a given environment
cartilage
firm but flexible substance, found in regions of vertebrate skeletons, such as the ribs, that need to bend
cellular respiration
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
cellulose
complex carbohydrate that constitutes the cell walls of plants and protists
cerebellum
part of the brain that ensures that movements are coordinated and balanced
cerebrum
part of the brain that controls all voluntary movement, sensory perception, speech, memory, and creative thought
chemical cycles
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
chemosynthesis
synthesizing organic compounds by energy derived from chemical reactions rather than from the energy of the sun
chitin
rough polysaccharide that constitutes the cell wall of fungi and exoskeleton of arthropods
circadian rhythms
behavior cycles that depend on time of day
circulatory system
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
climax community
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
codominance
phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in a heterozygote
cold-blooded
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
community
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
competition
struggle for survival between organisms or populations that use similar resources and occupy similar niches
contractile vacuole
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).
cytosol
The main component of the cytoplasm. It is a grayish, gel-like liquid containing the nucleus, organelles, and cytoskeleton.
dicot
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.
disaccharide
A sugar compound consisting of two carbohydrate monomers.
ecological succession
The progression of plant life and attendant animal life in a given geographic location, from pioneer plant to climax community.
ecology
The study of the interactions and relationships of populations with each other and their abiotic environments.
ecosystem
A community of organisms and its abiotic environment.
ectotherm
cold-blooded
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.
endocrine system
Control system of the body that functions by releasing hormones into the bloodstream.
endocytosism
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.
endoskeleton
An interior skeleton found in vertebrates made of bone and cartilage.
endotherm
warm-blooded
energy pyramid
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.
excretory system
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.
exoskeleton
A rigid, chitinous protective structure that surrounds the bodies of arthropods and provides support.
facilitated diffusion
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.
FADH2
A molecule that stores energy for harvest by the electron transport chain.
fermentation
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.
gallbladder
An organ that stores the bile produced by the liver and releases it to the small intestine during digestion.
gametophyte
A haploid plant or plant structure that produces haploid gametes through mitosis.
ganglion
a simple cluster of nerve cells that acts as a coordinating center
gene flow
The movement of genes, within a population or between populations, through mating.
genetic code
The series of codons that make up an organism's DNA.
grafting
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.
Gram staining
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.
guard cells
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.
gymnosperm
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.
heart
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.
heredity
The genetic transmission of traits from parents to offspring, so that offspring resemble their parents. Traits transmitted this way are called hereditary traits.
heterotrophs
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.
hydrogen bond
A weak bond between hydrogen and a set of other elements, including oxygen. Hydrogen bonds are a subset of dipole-dipole interactions.
hydrolysis
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
hydrophilic
soluble in water; these substance are either polar or ionic
hydrostatic skeleton
A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.
hypertonic
having greater concentration of solute than another solution
hypothalamus
major gland in the brain that is the bridge between the endocrine and nervous systems
hypotonic
having less concention of solute than another solution
imprinting
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
insulin
hormone secreted by the pancreas that reduces blood sugar levels; lack this hormone can result in diabetes
interphase
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.
intertidal zone
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.
isotonic
solutions containing equal concentrations of solute
kidney
organ of blood filtration in humans
kingdom
broadest category of biological taxonomy
Lamarckism
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.
learned behavior
Behavior that an organism picks up over the course of its life. Three types of learned behavior are habituation, conditioning, and associative learning.
Leeuwenhoek
made the first observations of bacteria and protozoa using single-lens microscopes of his own design
ligament
Connective tissue between bones
linked genes
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.
lymphatic system
A means of returning blood fluid, lymph, that has escaped from capillaries back into the bloodstream. Defended against foreign bodies by lymphocytes.
medulla oblongata
Part of the brain responsible for the control of involuntary functions such as breathing, cardiovascular regulation, and swallowing.
mesophyll
The internal tissue of a leaf between the epidermal cells; specialized for photosynthesis. Contains the palisade and spongy layer.
minerals
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.
muscle
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.
mutation
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.
myelin sheath
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.
myosin
Protein filaments that, along with actin, allow muscles to contract.
NADH
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.
natural selection
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.
nephridium
A blood filtration and excretory organ characteristic of segmented worms.
nephron
Tiny, tubule structures responsible for the filtering of blood in the kidneys of vertebrates.
neritic zone
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.
niche
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.
nitrogenous base
adenine, thymine, guanine, and cytosine in DNA; RNA is composed of adenine, uracil, guanine, and cytosine
notochord
A longitudinal rod of cells that forms in the least developed chordates and in embryonic stages of more developed chordates.
olfactory epithelium
Region near the top of the nasal cavity with chemoreceptors and neurons that inform the sense of smell.
osmosis
Process by which water naturally travels from an area of high water concentration to low water concentration.
oxidative phosphorylation
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.
pancreas
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.
parathyroid
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.
parthenogenesis
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.
pelagic zone
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.
peptide bond
The bond between the amino acids in a protein. Formed by dehydration synthesis.
peristalsis
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.
phloem
Vascular tissue composed of cells that are living at maturity; transports the products of photosynthesis throughout the plant body.
photic zone
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.
photoperiodism
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.
photosynthesis
The process by which plants and other autotrophic organisms convert light energy into organic materials, such as glucose.
phylogeny
The evolutionary relationships of a genetically similar group of organisms.
plasmids
Circular DNA molecules found in prokaryotes.
pollen
The male gametophyte of gymnosperms and angiosperms.
population
A group of interbreeding organisms in a particular locale exhibiting a unique set of characteristics such as patterns of growth and reproductive strategies.
predation
Term that refers to one organism eating another. Predation covers both carnivorous and herbivorous consumption.
producers
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.
pseudopods
Temporary cytoplasmic protrusions of ameboid cells that function in movement and food uptake by phagocytosis.
pyruvate
three-carbon end product of glycolysis; raw material of the Krebs cycle
reproductive isolation
The inability of individuals within a species to create offspring with members of any other species
respiratory system
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.
root
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.
root hair
An outgrowth of a plant root that provides an increased surface area for the absorption of water and dissolved minerals from the soil.
runner
Slender horizontal stem that can form new plants via specialized nodes.
semicircular canal
Fluid-filled structure within the ear that can detect balance.
sepal
Green, leaflike structure that encloses and protects the unopened flower bud.
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.
speciation
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.
spores
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.
sporophyte
A diploid plant or plant structure that produces haploid spores through meiosis.
stabilizing selection
When selection pressures favor the average form of a trait.
stamen
The male reproductive organ of the flower, consisting of an anther and filament.
stigma
The top part of the pistil, where pollen grains are received.
style
The shaft of the pistil that leads from the stigma down into the ovary.
substrate
The starting material that will undergo chemical change in a chemical reaction facilitated by an enzyme.
symbiosis
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.
synapse
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.
taxonomy
The study of biological classification.
tendon
Connective tissue between bones and muscles.
tissue
A group of closely connected and similar cells that cooperate to generate a specific structure or specialized function within an organism.
tracheophyte
A terrestrial plant with a vascular system.
transpiration
The process by which a plant loses water to its environment through evaporation.
trophic level
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.
tropism
Long-term growth of a plant toward or away from a stimulus.
tuber
Fleshy underground storage structure composed of an enlarged portion of the stem that has on its surface buds capable of producing new plants.
vascular cambium
Tissue that produces new vascular cells; lies between the xylem and phloem in dicot stems.
vascular tissue
A conductive component (either xylem or phloem) of the vascular system that transports food and nutrients throughout the plant body.
vegetative propagation
A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.
vein
A blood vessel that carries blood back to the heart. The blood in veins is not oxygenated, with the exception of the pulmonary vein.
vestigial structures
Bodily structures that developed in the past but no longer serve any function for an organism.
villi
Fingerlike projections in the small intestine that increase surface area and maximize the absorption of nutrients.
vitamins
Complex molecules that usually serve as coenzymes, assisting in physiological processes.
xylem
Vascular tissue composed of cells that are dead at maturity; transports water and dissolved minerals upward from the roots to the shoot.
abiotic factors
nonliving factors in an ecosystem
abscisic acid
plant hormone that inhibits growth
acoelomate
an animal that has no true coelom (e.g. flatworms)
active transport
movement of particles against a gradient from low concentration to high concentration; requires expenditure of energy
alcohol fermentation
the process by which certain cells convert pyruvic acid or pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the abscence of oxygen
allele
alternate form of a gene
alveoli
microscopic air sacs in the lung where diffusion of the respiratory gases oxygen and carbon dioxide occurs
amylase
enzyme that digests starch
aneuploidy
any abnormal condition of the chromosomes
anion
a negative ion
anticodon
the three-nucleotide sequence associated with tRNA
antigen
anything that triggers an antibody response
apoptosis
programmed cell death
ATP synthetase
structure in the membranes of mitochondria and chloroplasts where ATP is formed
autosomes
chromosomes other than the sex chromosomes (humans have 44 in each body cell)
auxins
growth hormones in plants that are responsible for phototropisms and apical dominance
backcross
a technique to determine whether an individual plant or animal showing the dominant trait is homozygous dominant or heterozygous
biological magnification
organisms at higher trophic levels have a greater concentration of accumulated toxins stored in their bodies than those at lower trophic levels
biosphere
the global ecosystem
biotic factor
includes all the organisms with which an organism might react in an ecosystem
biotic potential
the maximum rate at which a population could increase under ideal conditions
bottleneck effect
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
buffers
chemicals that resist a change in pH
C-4
plants that are modified for dry environments
CAM
plants that keep their stomata closed during the day and open at night
cardiac sphincter
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
carbon fixation
incorporation of carbon dioxide into a sugar; occurs during the Calvin cycle
carotenoids
orange and yellow photosynthetic pigments
carpel
female part of a flower that produces the female gametophytes (ova); consists of an ovary, stigma, and style
carrying capacity
a limit to the number of individuals that can occupt one area at a particular time (K)
cation
a positive ion
centrioles
organelles responsible for the division of the cytoplasm in animal cells; consist of 9 triplets of microtubules arranged in a circle
centromere
specialized region of a chromosome that holds two sister chromatids together
centrosome
consists of two centrioles at right angles to each other; is important during cell division in animal cells
chitin
a polysaccharide that makes up the exoskeleton of insects and the cell walls of fungi
associative learning
a type of learning in which one stimulus becomes linked to another through experience
classical conditioning
a type of associative learning (e.g. Pavlov's dogs)
cleavage
rapid mitotic cell division of the zygote that begins immediately after fertilization
cnidocytes
cells that house the stingers in cnidarians
codominance
an inheritance pattern where both traits show at once
codon
three-nucleotide sequence associated with mRNA
coevolution
the mutual evolutionary set of adaptations of two interacting species
colon
another name for large intestine
commensalism
symbiotic relationship in which one organism benefits and one is not affected by the other (+/o)
community
consists of all the organisms living in one area
companion cells
make up phloem vessels along with sieve tube elements
conjugation
a primitive form of sexual reproduction where individuals exchange genetic material
continental drift
the theory that states that the continents are floating and moving very slowly; over millions of years seven separate continents formed Pangea
convergent evolution
type of evolution where unrelated species occupying the same environment and subjected to similar selective pressures show similar adaptations
cortex
specialized region in a plant root or stem for storage and support
cotyledon
food for the growing embryo in a dicot seed; made up of triploid cells (3n)
cristae
series of inner membranes in mitochondria where cellular respiration occurs
crop
structure in birds, insects, and earthworms for temporary storage of food
crossing-over
process in which homologous chromatids exchange genetic material; increases variation in gametes
cyclosis
movement of cytoplasm around the cell
cytokinesis
division of the cytoplasm
cytokinins
plant hormones that stimulate cell division and cytokinesis
dehydration synthesis
process by which molecules are bonded together to form a larger molecule with the removal of water (condensation)
deletion
a mutation where a piece of a gene or chromosome is lost
denature
characteristic of proteins that consists of a change in shape that stops the protein from functioning
diastole
relaxation of the ventricles of the heart (normal = 120 mmHg)
diffusion
the flow of molecules from a higher concentration to a lower concentration
digestion
enzymatic breakdown, hydrolysis, of food so that it is small enough to be assimilated into the body
dipeptide
a molecule consisting of two amino acids
directional selection
type of natural selection that is due to changing environmental conditions; one phenotype replaces another in the gene pool
disruptive selection
type of natural selection that increases the number of extreme types in a population at the expense of intermediate forms
divergent evolution
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
DNA polymerase
the enzyme that catalyzes the elongation of the new DNA strands during replication
duodenum
the first 10 inches of the small intestine where digestion is completed
ectoderm
the outermost layer of an embryo that develops into skin and the nervous system
egestion
removal of metabolic waste
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
endoderm
the innermost layer of an embryo that develops into the viscera or the digestive system
ER
organelle that transporta particles within the cytoplasm of a eukaryotic cell
endosperm
food for the growing embryo in a monocot seed; its cells are triploid (3n)
epididymis
part of the testes where sperm become motile
epiglottis
flap of cartilage in the back of the throat that directs food to the esophagus
erythrocytes
red blood cells
ethylene
plant hormone that promotes fruit ripening
excretion
the removal of metabolic wastes
exocytosis
the release of substances from a cell
exons
expressed sequences of DNA that code for particular polypeptides
extremophiles
organisms that live in extreme environments; make up the domain Archaea
fermentation
anaerobic phase of cellular respiration
filament
threadlike structure that holds up the anther in the male part of a flower
filtration
process that occurs in the nephron where nutrients and wastes diffuse from the glomerulus into Bowman's capsule
fission
division of an organism into two new cells; how protists reproduce
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
founder effect
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
fragmentation
a single parent organism breaks into parts that regenerate into new individuals; reproduction in sponges, planaria, and sea stars
frameshift
an error in the DNA in which the entire reading frame is altered; caused by an insertion or deletion
G3P
first sugar produced by photosynthesis (a.k.a. PGAL)
gastrin
digestive hormone that stimulates sustained secretion fo gastric juice from the stomach
gastrovascular cavity
primitive digestive cavity in hydra
gastrulation
the process by which a blastula develops into a gastrula with the formatino of three embryonic layers
gene flow
movement of alleles into or out of a population
genetic drift
change in the gene pool due to chance (e.g. bottleneck effect or founder effect)
genome
an organism's genetic material
genotype
the kind of genes an organism has
geographic isolation
separation by natural barriers (e.g. mounts, rivers) that may cause significant isolation
gibberellins
plant hormones that promote stem and leaf elongation
gizzard
structure in birds, insects, and earthworms where mechanical digestion of food occurs
glucagon
hormone released by the pancreas that raises blood sugar
glycerol
combines with fatty acids to make lipids
glycolysis
the anaerobic phase of aerobic respiration; one molecule of glucose breaks apart into two molecuels of pyruvate
Golgi apparatus
organelle that packages and secretes substances for the cell
gradualism
the theory that organisms descended from a common ancestor gradually over a long period of time in a linear or branching fashion
grana
membranes within chloroplasts that consist of thylakoid membranes and are the sites of the light-dependent reaction of photosynthesis
greenhouse effect
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
habituation
one of the simplest forms of learning in which an animal comes to ignore a persistent stimulus so it can go about its business
half-life
amount of time it takes for a radioactive isotope to decay to half its mass
halophiles
organisms that thrive in environments with high salt concentration
hemocoels
cavities in the body of insects (e.g. grasshoppers) for exchange of nutrients and wastes
histamine
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
histones
special proteins that wrap around DNA, forming the chromatin network
homeostasis
internal stability
homologous structures
the same internal bone structure, although the function of each varies; means that organisms have a common ancestor
Huntington's disease
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
hydrophobic
insoluble in water; these substances are nonpolar
incomplete dominance
an inheritance pattern characterized by blending of traints
ingestion
intake of nutrients
insertion
a mutation where on nucleotide inserts itself into an existing strand; this mutation can cause a frameshift
introns
"junk" DNA
inversion
a chromosoal fragment breaks off an reattaches to its original chromosome but in the reverse orientation
irritability
the ability to respond to stimuli
karyotype
procedure that anlyzes the size, shape, and number of chromosomes
Krebs cycle
first stage of the aerobic phase of cellular respiration that occurs in the inner matrix of the mitochondria
lacteal
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
leukocytes
white blood cells
lipid
type of organic molecule that consists of one glycerol plus three fatty acids
macroevolution
refers to speciatino, the formation of an entirely new species
lysosome
organelle that consists of digestive enzymes and is the principal site of intracellular digestion in the cell
Malpighian tubule
structures in grasshoppers for removal of the nitrogenous waste uric acid
meduse
upside-down bowl-shaped body type
meiosis
type of cell division in sexually reproducing organisms that produces monoploid gametes (n)
light-dependent reactions
part of photosynthesis that requires light, produces ATP, and releases oxygen
light-independent reactions
part of photosynthesis that does not require light directly, only the products of the light dependnet reactions; sugar (G3P) is the product
menopause
cessation of the menstrual cycle
mesoderm
the middle layer of an embryo that develops into blood, bones, and muscle
mRNA
carries messages directly from DNA in the nucleus to the cytoplasm during protein synthesis
metabolism
the sum total of all the life functions
microevolution
changes in one gene pool of a population over generations
microtubules
thick hollow tubes that make up cilia, flagella, and spindle fibers
middle lamella
layer of tissue between two cell walls of adjacent plant cells
mitochondria
organelle that produces ATP; present in both animals and plants
mitosis
type of cell division for growth and repair that produces two genetically identical daughter cells with the same chromosome number as the parent
monotremes
egg-laying mammals
mutualism
symbiotic relationship where both organisms benefit (+/+)
nematocysts
stingers found in cnidocytes of cnidarians
nephridia
structure in earthworms for excretion of the nitrogen waste urea
net primary productivity
gross primary productivity minus the energy used by the primary producers for respiration
nondisjunction
an error that sometimes happens during meiosis in which homologous chromosomes fail to separate as they should
nucleolus
where components of ribosomes are synthesized; non-dividing region within the nucleus
ocular lens
eyepiece of a microscope
oogenesis
formation of ova by meiotic cell division
operant conditioning
trial and error learning
organogenesis
process by which cells continue to differentiate, producing organs from the three embryonic germ layers
oviduct
where fertilization occurs; after ovulation, the eff moves through the oviduct to the uterus; a.k.a. Fallopian tube
oxidation
loss of electrons
oxidative phosphorylation
process that provides most of the energy produced during cell respiration
oxytocin
hormone secreted by the poosterior pituitary that stimulates the uterus and causes contractions during labor
parallel evolution
two related species that have made similar evolutionary adaptations after their divergence from a common ancestor
parasitism
symbiotic relationship where one organism benefits while the other is harmed (+/-)
parthenogenesis
the development of an egg without fertilization; the resulting adult is haploid (n)
pathogen
organism that causes disease
pedigree
femily tree that indicates the phenotype of one trait being studied for every member of a family
phagocytosis
cellular process of engulfing food and encapsulating it in a vacuole
pharynx
throat
phenotype
the traits an organism expresses
photolysis
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
pinocytosis
cellular process by which cells take in large dissolved molecules
pioneer organisms
the first to colonize a barren environment in primary ecological succession
pith
specialized region in the root of a plant for storage
plasma
liquid portion of the blood
plasmodesmata
openings in cell walls of plants for the passage of materials from one cell to another
plasmolysis
cell shrinking; occurs when a cell is in a hypertonic environment
point mutation
a mutation in one nucleotide on DNA; sickle cell anemia is caused by it
polygenic
there are more than two allelic forms of a gene
polymers
molecules that are chains of repeating uniots; e.g. proteins and DNA
polyp
vase-shaped body
polyploid
an organism with extra sets of chromosomes (3n, 4n, etc.); common in plants
polysaccharides
molecules that consits of many monosaccharides joined together; e.g. starch and chitin
primary growth
vertical growth of a plant
prokaryotes
cells that have no internal membranes or internal organelles
prostate gland
large gland that secretes semen directly into the urethra
pseudocoelomate
an animal with a false coelom; e.g. roundworm
punctuated equilibrium
theory that proposes that new species appear suddenly after long periods of stasis
purines
nucleotides adenine and guanine
pyloric sphincter
band of muscle at the bottom of the stomach that keeps food in the stomach long enough to be digested
pyrimidines
nucleotides thymine and cytosine
reabsorption
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
recombinant DNA
the modern technique ot taking DNA from two sources and combining them into one molecule or cell
reduction
gain of electrons
regulation
ability to maintain homeostasis
resolution
a measure of clarity of an image seen under a microscope
respiration
metabolic processes that produce energy (ATP) for all the life processes
restriction enzymes
cut DNA at specific recognition sequences or sites
rRNA
strucutal RNA that is synthesized in the nucleolus; along with proteins, it makes up the ribosomes
ribosomes
structure in cells where proteins are synthesized
saprobes
organisms that obtain food from decaying organic matter
scrotum
sac outside the abdominal cavity that holds the testes
secondary growth
lateral growth of a plant
secretin
digestive hormone that stimulates the pancreas to release bicarbonate to neutralize acid in the duodenum
secretion
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
sessile
nonmoving
sex-linked
traits carried on the X chromosome
sieve tube elements
make up phloem, along with companion cells
sinoatrial node
pacemaker of the heart
sister chromatids
replicated chromosome consists of two of these, where on is an exact copy of the other
sodium-potassium pump
elaborate molecule that sits within neuron membranes and pumps sodium and potassium ions across the membrane
solute
substance that is dissolved in a solvent
solvent
substance that does the dissolving
somatic system
part of the nervous system that controls voluntary muscles
species
a population whose members have the potential to interbreed in nature andp roduce viable, fertile offspring
specific heat
amount of heat that must be absorbed in order for 1 gram of a substance to change its temperature by 1 degree Celsius
spermatogenesis
formation of sperm by meiotic cell division
spindle fibers
made of microtubules, these assist in cell division
spontaneous generation
the theory that living things emerge from nonliving or inanimate objects
stabilizing selection
type of natural selection that eliminates the extremes and favors the more common intermediate forms
stroma
part of the chloroplasts that holds the grana
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
symplast
system of transport within a plant consisting of openings in cell walls called plasmodesmata
synapsis
the process in which homologous chromosomes pair up; occurs during prophase I
systole
contraction of the ventricles of the heart
telomeres
special nonsense nucleotide sequences located at the ends of chromosomes that repeat thousands of times; protect DNA during cell division
testes
male gonads; the site of sperm formation
endosymbiosis
theory thats states that cell organelles were once tiny, free-living prokaryotic organisms that took up permanent residence inside larger prokaryotic organisms
thermophiles
organisms that thrive in very high termperatures
thylakoids
specialized membranes that make up the grana in chloroplasts, the site of the light-dependent reactions
tracheids
cells that, along with vessel elements, make up xylem
transcription
the process by which DNA makes RNA
tRNA
carries amino acids to the mRNA at the ribosome as proteins are synthesized
transformation
occurs in bacteria; the ability to transform themselves by transferring genetic factors from one bacteria cell to another
translation
the process in which the DNA code is translated into an amino acid sequence and a polypeptide is formed; occurs atthe ribosome
translocation
a fragment of a chromosome becomes attached to a nonhomologous chromosome
trisomy
having a chromosome in triplicate instead of duplication; down syndrome is caused by this on the 21st chromosome
tropic hormones
hormones that stimulate other glands to release their hormones
tropism
growth of a plant toward or away from a stimulus
turgid
a property of plant cells when they become swollen
urethra
tube that carries semen and urin in males; in females it carries only urine
uterus
where the blastula state of the embryo implnats and develops during pregnancy
vas deferens
duct that carries sperm during ejaculation from the testes to the penis
vesicles
small vacuoles
vessel elements
structures that, along with tracheids, make up xylem
villi
fingerlike projections that line the small intestine and absorb all nutrients that were previously released from digested food
intraspecific competition
competition between individuals of the same species
interspecific competition
competition between populations that may drive a population out of a community or push it to evolve a different niche to reduce competition
dehydration synthesis
process by which two monosaccharides are joined, thus forming a disaccharide
hydrolysis
process that occurs during digestions to breakdown a compound
saturated
fats that are solid at room temperature
unsaturated
fats that are liquid at room temperature