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327 Cards in this Set

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Nonliving materials in the environment—such as elements, sunlight, and soil—that influence and are influenced by living (biotic) entities on the planet.
abiotic
A neurotransmitter released by neurons to excite an action potential or trigger a muscle to contract.
acetylcholine
Hydrogen ion (H+) donors. Very important in the chemical reactions of life because they are highly reactive. Have pH values below 7. They are the opposite of bases.
acids
Thin protein filaments that, along with myosin, allow muscles to contract.
actin
The part of an enzyme that interacts with, or binds to, a substrate.
active site
The movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration. The process requires energy.
active transport
The evolutionary process by which ancestral forms of an organism are diversified through adaptation to new environments.
adaptive radiation
The energy storage molecule for the cell. Consists of an adenosine molecule bonded to three phosphate groups. Each phosphate bond contains energy; by breaking these bonds, the cell can get the energy it needs for chemical reactions. Cells build this during cell respiration, using the raw material of glucose.
ATP (adenosine triphosphate)
Two glands located on the kidney that secrete epinephrine and norepinephrine (medulla) and cortisone and aldosterone (cortex)
adrenal glands
A form of cell respiration requiring oxygen . Much more efficient than anaerobic respiration; it produces 36 ATP for every molecule of glucose. Proceeds in three stages: glycolysis, the Krebs cycle, and the electron transport chain.
aerobic respirtation
A specific form or possible version of a gene having multiple versions. May be dominant or recessive.
allele
The frequency with which a particular allele for a certain characteristic appears among all possible alleles for that characteristic in a population.
allelic frequency
The fluctuation between the diploid (sporophyte) and haploid (gametophyte) life stages that occur in plants.
alternation of generations
The monomer of a protein. A central carbon attached to an amino group (–NH2), a carboxyl group (–COOH), and a hydrogen atom (–H).
amino acid
A form of cell respiration that does not use oxygen. Less efficient than the aerobic variety and produces just 2 ATP per molecule of glucose. Has two stages: glycolysis and fermentation.
anaerobic respiration
A trait that is morphologically and functionally similar to that of a different species but that arose from a distinct, ancestral condition.
analagous trait
The stage of mitosis in which sister chromosomes are separated and pulled to opposite ends of the cell by microtubules; the fourth stage of the first meiotic division (meiosis I), during which maternal and paternal homologous pairs are separated on microtubules; the fourth stage of the second meiotic division (meiosis II), during which either maternal or paternal sister chromatids are separated on microtubules.
anaphase
A vascular flowering plant in which seeds are enclosed inside protective ovaries, such as fruit or flowers. Can be monocots or dicots.
angiosperm
Pollen-producing structure at the top of the stamen, the male reproductive organ of flowers.
anther
The sequence of three nucleotides on tRNA that pairs with a codon of mRNA at the A site of a ribosome during translation.
anticodon
A protein coat on the surface of red blood cells; a red blood cell may have a protein coat of type A, B, or AB. If the cell has none, it is called type O.
antigen
The largest artery in the body; carries oxygenated blood from the left ventricle of the heart.
aorta
Literally, zone without light. Part of the marine pelagic zone and begins 600 feet below the surface of the ocean. Only chemosynthetic organisms, scavengers, and predators are able to survive in this habitat.
aphotic zone
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.
artery
The involuntary half of the peripheral nervous system. Divided into 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.
autonomic nervous system
Any chromosome that is not a sex chromosome. Humans have 44 , in 22 homologous pairs. The two sex chromosomes are the twenty-third pair of chromosomes.
autosomes
An organism that can produce the organic molecules and energy necessary for life through the processes of photosynthesis or chemosynthesis. They do not rely on other organisms for food. In a food web, they are producers.
autotroph
One in a class of plant hormones that stimulates (among other things) cell elongation, secondary tissue growth, and fruit development.
auxin
An ion or compound that removes H+ ions from solution. Often substances that release hydroxide ions (OH–). Have pH values above 7. They are the opposite of acids.
bases
An emulsifier of fats secreted by the liver and stored in the gallbladder for release in the small intestine.
bile
Asexual reproduction found in prokaryotes in which a cell divides into two equal daughter cells by a nonmitotic process.
binary fission
The amount of living matter in a given ecosystem. Because only 10 percent of energy is transferred between trophic levels, this of lower trophic levels is greater than this of subsequent trophic levels: this of producers > this of primary consumers > this of secondary consumers > this of tertiary consumers.
biomass
A particular geographic area with a common climate and characteristic plant and animal life. There are six major terrestrial and two aquatic. The six terrestrial types of this are tropical rain forest, savanna, desert, temperate deciduous forest, taiga, and tundra. The two aquatic types of this are marine and freshwater. Each is characterized by specific climax communities.
biomes
The liquid that carries nutrients and oxygen to the cells and carries carbon dioxide and nitrogenous wastes away.
blood
Rigid structures composed of living cells rooted in a matrix of calcium, phosphate salts, and collagen fibers.
bone
The center of the central nervous system.
brain
A lower terrestrial plant (often a moss or liverwort) that lacks a vascular system and is dependent on environmental moisture for reproductive and nutritive functions.
bryophyte
Asexual reproductive process in which a small portion of the cell membrane and cytoplasm receive a nucleus and pinch off from the parent cell.
budding
Solutions that resist change in pH even when acids and bases are added.
buffer
Roughly spherical underground bud containing additional buds that can develop asexually into new plants.
bulb
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. Also called the dark reactions.
Calvin cycle
Tiny blood vessels able to branch through the body and deliver oxygen and nutrients to every cell.
capillary
The central element of life; has the ability to form bonds with up to four other elements or molecules at the same time.
carbon
The maximum number of individuals in a population that can be sustained in a given environment. As populations become increasingly concentrated, competition for food and space, predation, and disease all determine this
carrying capacity
A firm but flexible substance, found in regions of vertebrate skeletons, such as the ribs, that need to bend.
cartilage
The smallest unit of life, consisting of a solution of organic molecules enclosed by a plasma membrane.
cell
A process in which cells reproduce. First the cell replicates its DNA and then divides into two daughter cells. The two main phases are interphase and mitosis.
cell cycle
The phospholipid bilayer that surrounds all cells, regulating the passage of molecules in and out of the cell.
cell membrane
The 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.
cellular respiration
The doctrine that every living organism is composed of cells and that all cells come only from other preexisting cells.
cell theory
A rigid structure that surrounds the outer membrane of some cells and helps maintain their shape. In plants it contains cellulose; in fungi it contains chitin; in prokaryotes it typically contains peptidoglycan.
cell wall
A complex carbohydrate that constitutes the cell walls of plants and protist molds.
cellulose
The brain and the spinal cord. Acts as the central command center of the body. Mostly made up of interneurons.
central nervous system (CNS)
A structure in the cell that plays an important role in cell replication. During prophase, migrate to the poles of the cell and form the mitotic spindle, which allows the chromosomes to be organized and split when the cell divides.
centriole
Part of the brain. Makes sure that movements are coordinated and balanced.
cerebellum
Part of the brain. Controls all voluntary movement, sensory perception, speech, memory, and creative thought.
cerebrum
Inorganic elements move through the biotic and abiotic aspects of an ecosystem. The two most are the carbon and nitrogen cycles.
chemical cycles
Synthesizing organic compounds by energy derived from chemical reactions rather than from the energy of the sun.
chemosynthesis
A rough polysaccharide that constitutes the cell wall of fungi and exoskeleton of arthropods.
chitin
A pigment located within a chloroplast that absorbs light in plant cells, helping to convert light energy into biological energy through the process of photosynthesis.
chlorophyll
A double-membrane-bound organelle responsible for photosynthesis that contains chlorophyll and is found in plant cells.
chloroplast
The stringy web of genetic material and histone proteins found in the nucleus of eukaryotic cells. During cell division, each strand of DNA coils to form a chromosome.
chromatin
A physical structure composed of a single long strand of DNA (and associated proteins), containing along its length many genes. The human genome consists of 46 contained within the nucleus of each cell.
chromosome
Short, hairlike projections found on eukaryotic cells that can help the cell move or can sweep food particles toward the mouth.
cilia
Behavior cycles that depend on time of day.
circadian rhythms
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. The pulmonary circuit carries blood to the lungs to be oxygenated, while the systemic circuit carries oxygenated blood to the body.
circulatory system
another name for the krebs cycle
citric acid cycle
A combination of plant and animal forms that dominate mature ecological communities; unique and shaped by various factors, including temperature, rainfall, and soil acidity.
climax community
A phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in a heterozygote. Blood type is an example.
codominant
A three-nucleotide sequence in a DNA or mRNA molecule. Each specifies a single amino acid.
codon
A compound that regulates activity by binding to an enzyme to tell it when to catalyze a reaction.
coenzyme
Animals that are unable to retain heat produced by metabolic activities. Also known as ectothermic.
cold-blooded
The many populations that interact in a given geographical locale. Exhibit particular interactions such as competition, symbiosis, predation, and food relationships. They also undergo ecological succession.
community
A rough polysaccharide that constitutes the cell wall of fungi and exoskeleton of arthropods.
chitin
A pigment located within a chloroplast that absorbs light in plant cells, helping to convert light energy into biological energy through the process of photosynthesis.
chlorophyll
A double-membrane-bound organelle responsible for photosynthesis that contains chlorophyll and is found in plant cells.
chloroplast
The stringy web of genetic material and histone proteins found in the nucleus of eukaryotic cells. During cell division, each strand of DNA coils to form a chromosome.
chromatin
A physical structure composed of a single long strand of DNA (and associated proteins), containing along its length many genes. The human genome consists of 46 contained within the nucleus of each cell.
chromosome
Short, hairlike projections found on eukaryotic cells that can help the cell move or can sweep food particles toward the mouth.
cilia
Behavior cycles that depend on time of day.
circadian rhythms
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. The pulmonary circuit carries blood to the lungs to be oxygenated, while the systemic circuit carries oxygenated blood to the body.
circulatory system
another name for the krebs cycle
citric acid cycle
A combination of plant and animal forms that dominate mature ecological communities; unique and shaped by various factors, including temperature, rainfall, and soil acidity.
climax community
A phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in a heterozygote. Blood type is an example.
codominant
A three-nucleotide sequence in a DNA or mRNA molecule. Each specifies a single amino acid.
codon
A compound that regulates activity by binding to an enzyme to tell it when to catalyze a reaction.
coenzyme
Animals that are unable to retain heat produced by metabolic activities. Also known as ectothermic.
cold-blooded
The many populations that interact in a given geographical locale. Exhibit particular interactions such as competition, symbiosis, predation, and food relationships. They also undergo ecological succession.
community
The struggle for survival between organisms or populations that use similar resources and occupy similar niches.
competition
Competition between populations that may drive a population out of a community or push it to evolve a different niche to reduce competition.
interspecific competitiom
Competition between individuals of the same species.
intraspecific competition
Heterotrophic organisms within the food web of a community.
consumer
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).
contractile vacuole
After releasing its ovum (ovulation), the follicle becomes this, which produces progesterone for the continued buildup of the uterine wall.
corpus luteum
The exchange of genetic information between homologous chromosomes during meiosis I. Can disrupt the normal linkage between genes on the same chromosome.
crossing over
The final part of mitosis, in which a cell with duplicated contents splits into two independent cells.
cytokenesis
The entire content of the cell outside the nucleus, including the membrane-bound organelles and the cytosol.
cytoplasm
A system of protein filaments found throughout the cytoplasm of eukaryotic cells, which provides structural support for the cell.
cytoskeleton
The main component of the cytoplasm. It is a grayish, gel-like liquid containing the nucleus, organelles, and cytoskeleton.
cytosol
English naturalist (1809–1882) who proposed the modern theory of evolution through natural selection
Charles Darwin
Organisms that consume waste products and dead organic material and constitute part of the food web, which also includes producers and consumers. Also called saprophytes.
decomposer
A common biochemical reaction in which a new compound is formed by the joining of two compounds to release water. Occurs in the synthesis of polysaccharides and polypeptides. The reverse of hydrolysis.
dehydration synthesis
A type of nucleic acid polymer built from sugar-phosphate backbones and nitrogenous bases. DNA’s sugar, deoxyribose, has one fewer oxygen atom than ribose, found in RNA. The nitrogenous bases adenine, cytosine, guanine, and thymine are used in DNA.
deoxyribonucleic acid
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.
dicot
The transport or natural drift of molecules traveling from an area of higher concentration to an area of lower concentration.
diffusion
The system of organs that converts food to usable nutrients through mechanical and chemical breakdown. Important components of the system are the alimentary canal, glands, esophagus, stomach, small intestine, large intestine, and rectum.
digestive system
The total number of chromosomes present in a somatic cell.
diploid number
A sugar compound consisting of two carbohydrate monomers.
disaccharide
Refers to an allele that controls the phenotype even when a different allele is also present, as in a heterozygote. Can also refer to the trait or phenotype produced by a dominant allele. Also known as Mendel’s law of dominance, based on Gregor Mendel’s observations that when two purebred individuals with different forms of the same trait are mated, only one of the two forms appears in the first generation of offspring
dominant
Sensory organ capable of detecting sound.
ear
The progression of plant life and attendant animal life in a given geographic location, from pioneer plant to climax community.
ecological succession
The study of the interactions and relationships of populations with each other and their abiotic environments.
ecology
A community of organisms and its abiotic environment.
ecosystem
another word for cold-blooded
ectotherm
The female gamete in sexual reproduction; also called an ovum.
egg
An instrument that uses an electron beam to form clear and highly magnified images of microscopic structures. Cannot take pictures of living organisms.
electron microscope
The final stage of aerobic respiration. Establishes an electrochemical gradient across the inner mitochondrial membrane that powers the synthesis of ATP in oxidative phosphorylation.
electron transport chain
Before birth, the maturing cells that will grow into a fully formed organism.
embryo
Control system of the body that functions by releasing hormones into the bloodstream.
endocrine system
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.
endocytosis
A network of membrane-bound tubes and sacs in the cytoplasm; major site of protein and lipid synthesis.
endoplasmic reticulum
An interior skeleton found in vertebrates made of bone and cartilage.
endoskeleton
Another word for warm-blooded
endotherm
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.
energy pyramid
Biological catalysts made from proteins.
enzyme
Hormone that stimulates the growth of the uterine lining during pregnancy and that develops and maintains the female secondary sex characteristics, such as the development of mammary glands, a narrower waist and wider hips, axillary and pubic hair, and a higher-pitched voice.
estrogen
An organism whose cells have membrane-bound intracellular organelles, including a nucleus containing multiple chromosomes.
eukaryote
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.
excretory system
Process by which molecules are secreted from the cell. Occurs when a vesicle fuses with the cell membrane and releases its contents to the outside.
exocytosis
A rigid, chitinous protective structure that surrounds the bodies of arthropods and provides support.
exoskeleton
Sensory organ capable of detecting light.
eye
Diffusion of molecules that cannot pass through the cell membrane independently, but rather through permeable protein channels embedded in the membrane. Does not require energy.
facilitated diffusion
FADH2
A molecule that stores energy for harvest by the electron transport chain.
Duct that connects the ovaries with the uterus; the passage through which the ovulated egg travels from the ovaries to the uterus.
fallopian tube
The second stage of anaerobic respiration, which produces the NAD+ necessary for glycolysis. There are two types : alcoholic and lactic acid. Yeast engage in alcoholic, while muscle cells lacking oxygen produce lactic acid.
fermentation
The name given to an embryo after it has developed organs.
fetus
A whiplike structure projecting from the surface of some cells and single-celled organisms; coordinated waving of this allows the organism to swim.
flagella
Theory describing the cell membrane as a dynamic structure with proteins floating, yet partially embedded, in a sea of phospholipids.
fluid-mosaic model
A linear relationship of predators and prey.
food chain
Many connected food chains that exhibit the relationships of all predators to all prey.
food web
The grouping of fossilized remains according to relative and absolute age.
fossil record
An organ that stores the bile produced by the liver and releases it to the small intestine during digestion.
gallbladder
A haploid sex cell (either an egg or sperm cell).
gamete
A haploid plant or plant structure that produces haploid gametes through mitosis.
gametophyte
A simple cluster of nerve cells that acts as a coordinating center. In more sophisticated organisms, evolved into a brain and spinal cord.
ganglion
The fundamental unit of heredity, composed of a stretch of DNA.
gene
The movement of genes, within a population or between populations, through mating.
gene flow
The series of codons that make up an organism’s DNA.
genetic code
The entire set of specific alleles present in an organism or cell: the genetic information that (together with the environment) defines the phenotype. Often refers only to the alleles controlling a particular trait of interest.
genotype
Cells that lead to the production of gametes. Produced by meiosis.
germ cell
A monosaccharide with the chemical formula C6H12O6. Used as the raw material for cellular respiration.
glucose
The first step of aerobic and anaerobic respiration. Produces ATP while converting glucose to pyruvate, which is the raw material for the rest of aerobic respiration.
glycolysis
A series of membrane-bound sacs in the eukaryotic cytoplasm; takes proteins produced by the endoplasmic reticulum and packages and secretes them to various destinations inside and outside of the cell.
Golgi apparatus
Sex organs that produce gametes. Also release sex hormones, such as testosterone, estrogen, and progesterone.
gonads
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.
grafting
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.
Gram staining
Epidermal plant cells found in pairs surrounding the stomata of leaves. By increasing or decreasing their size, regulate gas exchange by opening and closing individual stoma.
guard cells
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.
gymnosperm
The number of homologous pairs in a cell. Equal to half the diploid number.
haploid number
The muscular organ that pumps blood through the circulatory system.
heart
The genetic transmission of traits from parents to offspring, so that offspring resemble their parents.
hereditary
Organisms that can only get the organic molecules and energy necessary for life through the consumption of other organic matter.
heterotroph
A situation in which an individual possesses two dissimilar alleles for the same gene.
heterozygous
Chromosomes containing the same series of genes; they may or may not carry the same alleles. Humans receive one set of 23 paternal chromosomes from their male parent and another set of 23 maternal chromosomes from their female parent.
homologous chromosome
A trait found in different species that are morphologically and functionally similar and that comes from the same ancestral condition.
homologous trait
A situation in which an individual has the exact same allele on both homologous chromosomes.
homozygous
A chemical messenger that can be made of either peptides or lipids. Secreted by glands in one part of the body.
hormone
A genetic mixture; the offspring of two genetically different parents.
hybrid
Having a reluctance to mix with water; usually nonpolar molecules.
hydrophobic
A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.
hydrostatic skeleton
A situation in which the concentration of solutes in a solution is higher than what it contains.
hypertonic
Part of the brain responsible for temperature regulation, controlling hunger and thirst, and managing water balance. It also helps generate emotion.
hypothalamus
A situation in which the concentration of solutes in a solution is lower than what an organism contains. An example is a paramecium in pond water: the organism has more solutes than its environment, so water flows into the cell by osmosis. Paramecia have evolved contractile vacuoles to keep from exploding.
hypotonic
Instinctual behavior in which social bonds are formed during early development. Typically used with the example of a newly hatched bird or other animal identifying and treating the first moving object it sees as its mother.
imprinting
Occurs when two different alleles of the same gene are both partially expressed in a heterozygote. The resulting phenotype is intermediate between the homozygous phenotypes of the two alleles.
incomplete dominance
Mendel’s conclusion that during gamete formation, the segregation of one pair of genes has no influence over the segregation of another pair of hereditary units. Two different traits will thus be inherited independently of each other. This law holds true, except for linked genes. It is often called Mendel’s second law.
independent assortment
A crucial, and incorrect, aspect of Lamarck’s theory of evolution. Lamarck believed that the traits a parent acquired during its lifetime would be passed on to its offspring.
inheritance of acquired traits
Behavior that is hardwired into the brain of an organism; behavior that does not have to be learned.
instinct
Hormone secreted by the pancreas that reduces blood sugar levels.
insulin
The phase of the eukaryotic cell cycle in which the cell prepares for division, primarily by replicating its DNA.
interphase
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.
intertidal zone
An atom or molecule that has lost or gained an electron and consequently has a positive or negative charge.
ion
A situation in which the concentration of solutes in a solution is equivalent to what it contains.
isotonic
A photograph of the chromosomes from an individual cell, usually lined up in homologous pairs, according to size. Missing, extra, or abnormal chromosomes can then be easily identified, aiding in the diagnosis of genetic disorders.
karyotype
The organ of blood filtration in humans.
kidney
The broadest category of biological taxonomy.
kingdom
A metabolic pathway in aerobic organisms in which acetyl-CoA combines with oxaloacetic acid to form citric acid. The cycle produces energy in the forms of ATP, NADH, and FADH2.
Krebs cycle
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.
Lamarckism
Behavior that an organism picks up over the course of its life. Three types of are habituation, conditioning, and associative learning.
learned behavior
Dutch clothing salesman (1632–1723) who made the first observations of bacteria and protozoa using single-lens microscopes of his own design.
Antonie van Leeuwenhoek
Connective tissue between bones.
ligament
Genes that are located close together on the same chromosome.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.
linked genes
A means of returning blood fluid, lymph, that has escaped from capillaries back into the bloodstream.
lymphatic system
White blood cell that is specialized to kill specific invading bacteria. Three types work in coordination: B cells, helper T cells, and killer T cells.
lymphocyte
The organ of blood filtration in arthropods.
Malpighian tubules
A type of cellular reproduction that results in the formation of four haploid cells from one diploid cell.
meiosis
Austrian monk and scientist. Through a series of experiments with pea plants, he discovered the basic laws of heredity, including dominance, segregation, and independent assortment.
Gregor Mendel
A 28-day hormone sequence that defines the production, ovulation, and menstruation of eggs in the female reproductive system
menstrual cycle
The internal tissue of a leaf between the epidermal cells; specialized for photosynthesis. Contains the palisade and spongy layer.
mesophyll
An RNA molecule that specifies the amino acid sequence of a protein. In transcription, copy the genetic information stored in DNA, hen bring the recipes for proteins from the nucleus to ribosomes in the cytoplasm.
messenger RNA (mRNA)
The second stage of mitosis in which microtubules align the chromosomes in the center of the cell along the metaphase plate; the stage of meiosis I and II during which the chromosomes align at the center of the cell.
metaphase
Inorganic molecules required by the body to carry out life processes.
minerals
Double membrane-bound organelles that produce most of the energy in eukaryotic cells through the process of aerobic (cellular) respiration, which generates ATP.
mitochondria
The phase of the eukaryotic cell cycle in which the cell divides. The four steps are prophase, metaphase, anaphase, and telophase.
mitosis
A complex of microtubules that forms between opposite poles of a cell during mitosis.
mitotic spindle
A molecule or gene sequence that has a constant rate of change through accumulation of neutral substitutions and is therefore a good measuring stick for the relatedness of different species.
molecular clock
A flowering plant (angiosperm) that possesses one cotyledon during embryonic development. Usually has fibrous roots, flower parts in threes, and parallel veins in leaves.
monocot
Each of the repeating units that make up a polymer.
monomer
A carbohydrate monomer. Glucose and fructose are common examples.
monosaccharide
Structures that create movement in an organism by contracting under a stimulus from a neuron.
muscle
An error in the sequence of nucleotides in DNA or RNA that in turn affects the production of proteins.
mutation
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.
myelin sheath
Protein filaments that, along with actin, allow muscles to contract.
myosin
An energy-carrying coenzyme produced by glycolysis and the Krebs cycle. Carries energy to the electron transport chain, where it is stored in ATP.
NADH
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
A blood filtration and excretory organ characteristic of segmented worms.
nephridium
Tiny, tubule structures responsible for the filtering of blood in the kidneys of vertebrates.
nephron
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.
neritic zone
Control system of the body that functions by sending impulses through neurons to receive information and spur muscles to action.
nervous system
The functional unit of the nervous system.
neuron
The unique role a population plays in a community.
niche
One of the nitrogen-containing bases in DNA and RNA nucleotides.
nitrogenous base
Occurs when a pair of homologous chromosomes fails to separate during gamete formation. The offspring produced from these gametes have either one too many or one too few of a particular chromosome.
nondisjunction
A longitudinal rod of cells that forms in the least developed chordates and in embryonic stages of more developed chordates.
notochord
A dense, spherical body inside the nucleus of a cell. Makes the RNA that is a structural component of the ribosomes.
nucleolus
The monomer of a nucleic acid.
nucleotide
The large, central organelle of eukaryotes. Contains the genetic material of the cell and controls cellular activities.
nucleus
Region near the top of the nasal cavity with chemoreceptors and neurons that inform the sense of smell.
olfactory epithelium
The process in which haploid egg cells (ova) form through meiotic division.
oogenesis
A discrete unit of tissues that work together to perform specific functions within the body.
organ
Specialized membrane-bound structure in a cell that performs a specific function.
organelle
Process by which water naturally travels from an area of high water concentration to low water concentration.
osmosis
In animals, the female gonad that produces ova and sex hormones.
ovary
Structure that contains the female gametophyte and gametes; after fertilization, develops into a seed.
ovule
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.
oxidative phosphorylation
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.
pancreas
Four small glands embedded on the posterior surface of the thyroid gland. Produce a hormone that regulates the level of calcium in the bloodstream.
parathyroid
Asexual reproduction in which an unfertilized gamete (usually female) produces female offspring.
parthenogenesis
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.
pelagic zone
The bond between the amino acids in a protein. Formed by dehydration synthesis.
peptide bond
The pathways by which the central nervous system receives sensory information from the body and sends commands to muscles.
peripheral nervous system
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.
peristalsis
A scale for measuring the presence or absence of hydrogen ions in solution. Values between 0 and 7 indicate an excess of hydrogen ions. Such solutions are called acids. Values between 7 and 14 indicate the presence of compounds that counteract the effects of hydrogen ions. Such solutions are called bases.
pH
A type of white blood cell that kills invading cells by ingesting them.
phagocyte
A form of endocytosis in which a cell ingests a solid particle.
phagocytosis
The entire set of observable characteristics of an organism or cell; the physical traits of an organism.
phenotype
Vascular tissue composed of cells that are living at maturity; transports the products of photosynthesis throughout the plant body.
phloem
Type of lipid found in cell membranes.
phospholipid
A double layer of phospholipid molecules that provides the structure of the cell membrane. Formed naturally from the alignment of the two layers of lipids such that their hydrophobic tails point inward toward each other and their hydrophilic phosphate heads point outward into the watery environments inside and outside of the cell.
phospholipid bilayer
Literally, zone with light. 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.
photic 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.
photoperiodism
The process by which plants and other autotrophic organisms convert light energy into organic materials, such as glucose.
photosynthesis
The evolutionary relationships of a genetically similar group of organisms.
phylogeny
Form of endocytosis during which liquids are taken into the cell through the invagination of the cell membrane.
pinocytosis
The first population to move into a geographic location and begin the process of ecological succession.
pioneer population
The female reproductive organ of the flower, composed of a stigma, style, and ovary; sometimes called the carpel.
pistil
The “master” gland of the endocrine system.
pituitary
A structure that develops in the uterus during pregnancy; filter through which the embryo gains nutrition from the mother.
placenta
Circular DNA molecules found in prokaryotes.
plasmids
The male gametophyte of gymnosperms and angiosperms.
pollen
A large molecule consisting of the same or similar units attached in a series, forming a chain.
polymer
A group of interbreeding organisms in a particular locale exhibiting a unique set of characteristics such as patterns of growth and reproductive strategies.
population
Term that refers to one organism eating another.
predation
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
Hormone that prepares the uterus for embryo implantation and helps to maintain pregnancy.
progesterone
A single-celled organism that completely lacks membrane-bound intracellular organelles such as a nucleus or mitochondria;
prokaryote
The first stage of mitosis, meiosis I, and meiosis II, during which the chromosomes become visible and the centrioles move to opposite ends of the cell and begin to form the spindle.
prophase
Temporary cytoplasmic protrusions of ameboid cells that function in movement and food uptake by phagocytosis.
pseudopod
A pictorial method of showing the gene combinations (genotypes) of offspring that might result from an experimental genetic cross of two parents.
Punnett square
The three-carbon end product of glycolysis.
pyruvate
Refers to an allele that cannot control the phenotype unless it is the only kind of allele present, as in a homozygote or hemizygote.
recessive
The inability of individuals within a species to create offspring with members of any other species.
reproductive isolation
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.
respiratory system
One type of nucleic acid polymer.Can have the nitrogenous bases adenine, cytosine, guanine, and uracil.
ribonucleic acid (RNA)
Organelle responsible for protein synthesis.
ribosome
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
An outgrowth of a plant root that provides an increased surface area for the absorption of water and dissolved minerals from the soil.
root hair
Slender horizontal stem that can form new plants via specialized nodes.
runner
another word for decomposer
saprophyte
Mendel’s conclusion that individuals have two copies of each gene, and that these copies separate randomly during gamete formation, one copy per gamete. This law is true except for genes on sex chromosomes in males, who have only one copy of each such gene. It is often called Mendel’s first law.
segregation
Fluid-filled structure within the ear that can detect balance.
semicircular canal
Green, leaflike structure that encloses and protects the unopened flower bud.
sepal
a gene located on a sex chromosome or to a trait defined by such a gene. Such traits will appear with different frequencies in males and females, and males and females will differ in their ability to transmit the trait to their offspring.
sex-linked
Any plant or animal cell that is not a germ cell, meaning it is not passed down to offspring. The class of cell formed during mitosis.
somatic cell
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.
somatic nervous system
The development of a species through evolution. A species forms when its members become reproductively isolated from all other organisms.
speciation
A group of organisms defined by their ability to interbreed with only each other.
species
The male gamete in sexual reproduction.
sperm
The process in which haploid sperm cells form through meiotic division.
spermatogenesis
A long cylinder of nervous tissue that extends along the vertebral column from the head to the lower back. It controls some autonomic responses and connects the brain to the peripheral nervous system.
spinal cord
Usually unicellular and microscopic, are produced by protist molds, fungi, and plants and are able to develop into new individuals.
spores
A diploid plant or plant structure that produces haploid spores through meiosis.
sporophyte
When selection pressures favor the average form of a trait.
stabilizing selection
The male reproductive organ of the flower, consisting of an anther and filament.
stamen
The top part of the pistil, where pollen grains are received.
stigma
Small epidermal pores, surrounded by two guard cells, through which gases diffuse and water transpires in and out of a leaf.
stomata
The shaft of the pistil that leads from the stigma down into the ovary.
style
The starting material that will undergo chemical change in a chemical reaction facilitated by an enzyme.
substrate
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.
symbiosis
The gap between two neurons, spanning the space between the axon of one and the dendrites of the other.
synapse
Structures on the tongue that contain chemoreceptors, which respond to four main sensations—sour, salty, bitter, and sweet—to create the sense of taste.
taste buds
The study of biological classification.
taxonomy
The final stage of mitosis before cytokinesis. The nuclear envelope re-forms around separated sister chromatids and kinetochore microtubules disappear. Cell elongation also occurs during this phase. The final stage of the first meiotic division (meiosis I), during which chromosomes arrive at the poles of the cell and begin to recondense; the final stage of the second meiotic division (meiosis II), during which chromosomes arrive at the poles of the cell, the nuclear envelope begins to re-form, and the chromosomes begin to recondense.
telophase
Connective tissue between bones and muscles.
tendon
The male gonads; sperm and testosterone are produced here.
testes
A hormone necessary for sperm production in men. Also responsible for developing and maintaining the secondary sex characteristics of males, starting at puberty.
testosterone
Gland that produces the hormone thyroxine, which increases the metabolism of most of the cells in the body. Located in the neck.
thyroid
A group of closely connected and similar cells that cooperate to generate a specific structure or specialized function within an organism.
tissue
A terrestrial plant with a vascular system.
tracheophyte
Any observable feature or characteristic of an organism.
trait
An RNA molecule used in protein synthesis as a link helping to convert messenger RNA into amino acids.
transfer RNA
The process by which a plant loses water to its environment through evaporation.
transpiration
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.
trophic level
Long-term growth of a plant toward or away from a stimulus.
tropism
Fleshy underground storage structure composed of an enlarged portion of the stem that has on its surface buds capable of producing new plants.
tuber
Structure in the female reproductive system in which the embryo develops.
uterus
Tissue that produces new vascular cells; lies between the xylem and phloem in dicot stems.
vascular cambium
A conductive component (either xylem or phloem) of the vascular system that transports food and nutrients throughout the plant body.
vascular tissue
A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.
vegetative propagation
A blood vessel that carries blood back to the heart.
vein
An animal that has a skeletal rod of bone or cartilage running up its back, surrounding the nerve cord.
vertebrate
Bodily structures that developed in the past but no longer serve any function for an organism.
vestigial structure
Fingerlike projections in the small intestine that increase surface area and maximize the absorption of nutrients.
villi
Complex molecules that usually serve as coenzymes, assisting in physiological processes.
vitamins
Animals that have developed fat and fur, hair, or feathers in order to retain heat produced by metabolic activities. Also known as endothermic.
warm-blooded
Vascular tissue composed of cells that are dead at maturity; transports water and dissolved minerals upward from the roots to the shoot.
xylem
In sexual reproduction, the diploid product of the fusion of the father’s haploid sperm cell and the mother’s haploid ovum (egg) cell.
zygote