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Definition
| The process by which all living things assimilate energy and use it to grow. (3) |
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| The maintaining of a relatively stable internal physiological environment in an organism or steady-state equilibrium in a population or ecosystem. (3) |
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| Process of transmission of characteristics from parent to offspring. (3) |
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| A specialized compartment of a cell. Mitochondria are organelles. (4) |
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| A group of similar cells organized into a structural and functional unit. (5) |
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| A complex body structure composed of several different kinds of tissues grouped together in a structural and functional unit. (5) |
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| A group of individuals of a single species, occupying a given area at the same time. (5) |
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| The populations of different species that live together and interact in a particular place. (5) |
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| A community, together with the nonliving factors with which it interacts. (5) |
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| Properties that are present at higher levels of organization that are not apparent at simpler levels of organization; emergent properties result from the interactions of the components. (5) |
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| A level of taxonomic hierarchy; a species ranks next below a genus. (5) |
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| The area in which something exists or lives. |
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| Making decisions or drawing conclusions based on accepted principles used to explain specific observations. (8) |
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| Discovering general principles by careful examination of specific cases; making careful observations to infer a general principle. (8) |
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| A proposal that might be true. No hypothesis is ever proven correct. All hypotheses are provisional—proposals that are retained for the time being as useful but that may be rejected in the future if found to be inconsistent with new information. A hypotheses that stands the test of time—often tested and never rejected—is called a theory. (8) |
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| A well-tested hypothesis supported by a great deal of evidence. (11) |
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| The test of a hypothesis. An experiment that tests one or more alternative hypotheses and those that are demonstrated to be inconsistent with experimental observation and are rejected. (11) |
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| A series of steps, including careful observation, in which a hypotheses is tested. (14) |
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| This theory, developed in the 1800s by Matthias Schleiden and Theodor Schwann, has three principles: 1) all organisms are composed of cells; 2) cells are the smallest living things; and cells arise only from preexisting cells. (16) |
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| The theory that states that proteins encoded as genes in an organism’s DNA determine what the organism will be like. (16) |
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| Any substance that has mass and takes up space (44) |
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| A core (nucleus) of protons and neutrons surrounded by an orbiting cloud of electrons. The chemical behavior of an atom is largely determined by the distribution of its electrons, particularly the number of electrons in the outermost level. (44) |
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| A subatomic particle in the nucleus of an atom that carries a positive charge. The number of protons determines the chemical character of the atom because it dictates the number of electrons orbiting the nucleus and available for chemical activity. (44) |
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| A subatomic particle located within the nucleus of atom. Similar to a proton in mass, but as its name implies, a neutron is neutral and possesses no charge. (44) |
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| A subatomic particle with a negative electrical charge. The negative charge of one electron exactly balances the positive charge of one proton. Electrons orbit the atom’s positively charged nucleus and determines its chemical properties. (44) |
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| A substance that cannot be separated into different substances by ordinary chemical means. (44) |
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| The smallest unit of a compound that displays the properties of that compound. (48) |
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| The capacity to bring about change, to do work. (44) |
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| An atom in which the number of electrons does not equal the number of protons. An ion carries an electrical charge. (46) |
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| An atom that has the same number of protons but different numbers of neutrons. (46) |
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| process in which the nucleus of an unstable atom tends to break up into particles with lower atomic numbers (46) |
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| The preserved remains, tracks, or evidence of once-living organisms. (47) |
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| The length of time it takes for half of a radioactive substance to decay. (47) |
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| The force holding two atoms together. The force can result from the attraction of opposite charges (ionic bond) or from the sharing of one or more pairs of electrons (a covalent bond). (48) |
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| A chemical bond formed between ions as a result of the attraction of opposite electrical charges. (48) |
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| A chemical bond formed by the sharing of one or more pairs of electrons. (48) |
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| A molecular force formed by the attraction of the partial positive charge of one hydrogen atom of a water molecule with the partial negative charge of the oxugen atom of another. (49) |
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Definition
| A molecule with positively and negatively charged ends. One portion of a polar molecule attracts electrons more strongly than another portion, with the result that the molecule has electron –rich (-) and electron poor (+) regions, giving it magnet-like positive and negative poles. Water is one of the most polar molecules known. (49) |
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Definition
| Nonpolar molecules, which DO NOT form hydrogen bonds with water and therefore ARE NOT soluble in water. (52) |
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| polar molecules, which DO form hydrogen bonds with water and therefore ARE soluble in water. (52) |
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| Refers to the concentration of H+ ions in a solution. The numerical value of the pH is the negative of the exponent of the molar concentration. Low pH values indicate high concentrations of H+ ions (acids), and high pH values indicate low concentrations (bases). (53) |
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| A substance that resists changes in pH; a substance that can take up excess or release hydrogen ions (H+) into solution to maintain a stable pH. (55) |
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| a molecule formed by living organisms that consists of a carbon-based core with special groups attached. (60) |
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| A long chain of amino acids linked end to end by peptide bonds. Because the 20 amino acids that occur in proteins have side groups with very different chemical properties, the function and shape of a protein is critically affected by its particular sequence of amino acids. (62) |
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Definition
| The building blocks of proteins; small molecules with an amino group (-NH2) at one end, a carboxyl group (-COOH) at the other end, a hydrogen atom, and a functional (remainder or R) group. (62) |
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Definition
| Two or more amino acids linked by peptide bonds. (62) |
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Definition
| A covalent bond linking two amino acids. Formed when the positive (amino, or NH2) group at one end and a negative (carboxyl, or COOH) group at the other end undergo a chemical reaction and lose a molecule of water. (62) |
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Definition
| A general term for a long chain of amino acids linked end to end by peptide bonds. A protein is a long, complex polypeptide. (62) |
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Definition
| A nucleotide polymer. A long chain of nucleotides. Chief types are deoxyribonucleic acid (DNA), which is double-stranded, and ribonucleic acid (RNA), which is typically single-stranded. (67) |
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Definition
| Deoxyribonucleic acid – The basic storage vehicle or central plan of heredity information. It is stored as a sequence of nucleotides in a linear nucleotide polymer. Two of the polymers wind around each other like the outside and inside rails of a circular staircase. (67) |
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| Ribonucleic acid – A single-stranded polymer of nucleotides used by cells in making proteins using instructions encoded in DNA. (67) |
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Definition
| A single unit of nucleic acid, composed of a phosphate, a five-carbon sugar (either ribose or deoxyribose), and a purine or a pyrimidine. (67) |
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| Two long strands of DNA coiled together, a double corkscrew shape. (67) |
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| An organic compound consisting of a chain or ring of carbon atoms to which hydrogen and oxygen atoms are attached in a ratio of approximately 1:2:1. A compound of carbon, hydrogen, and oxygen having the generalized formula (CHcO)n, where n is the number of carbon atoms. (70) |
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| A loosely defined group of molecules that are insoluble in water but soluble in oil. Oils such as olive, corn, and coconut are lipids, as well as waxes, such as beeswax and earwax. (72) |
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| A subunit of lipids made up of a long chain of carbon and hydrogen atoms ending in a carboxyl (-COOH) group. (72) |
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| A typical fat made up of a backbone of glycerol with three fatty acids attached. (73) |
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Definition
| A semifluid matrix that occupies the volume between the nuclear region and the cell membrane. It contains the sugars, amino acids, proteins, and organelles (in eukaryotes) with which the cell carries out its everyday activities of growth and reproduction. (79) |
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| The minimum distance between two points where they can still be distinguished as two points. (80) |
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| Magnifier of the image of small objects. (80) |
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Definition
| A lipid bilayer with embedded proteins that control the cell’s permeability to water and dissolved substances. (82) |
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| The current model of the structure of the plasma membrane, suggesting a double layer of phospholipids with a variety of membrane proteins. (82) |
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Definition
| The basic foundation of all biological membranes. In such a layer, the nonpolar tails of phospholipid molecules point inward, forming a nonpolar zone in the interior of the bilayers. Lipid bilayers are selectively permeable and do not permit the diffusion of water-soluble molecules into the cell. (82) |
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Definition
| A simple organism that is small, single-celled, and has little evidence of internal structure. (85) |
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| An organism with cells characteristic of all life forms except primitive microorganisms such as bacteria. (85) |
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| Plant, fungi, and protest cells have these supportive walls outside the plasma membrane; plant cell walls are composed of cellulose while fungal cell walls are made up of chitin. (85) |
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| In a cytoplasm of all eukaryotic cells, a network of protein fibers that supports the shape of the cell and anchors organelles, such as the nucleus, to fixed locations. (86) |
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Definition
| A network of internal membranes in the cytoplasm of eukaryotic cells that form compartments and vesicles and participate in protein and lipid synthesis. (86) |
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| A spherical organelle (structure) characteristic of eukaryotic cells. The repository of the genetic information that directs all activities of a living cell. In atoms, the central core, containing positively charged protons and (in all but hydrogen) electrically neutral neutrons. (88) |
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| A group of Golgi bodies that packages proteins for export from the cells and forms secretory vesicles. (90) |
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Definition
| A tubular or sausage-shaped organelle 1 to 3 micrometers long. Bounded by two membranes, mitochondria closely resemble the aerobic bacteria from which they were originally derived. As chemical furnaces of the cell, they carry out its oxidative metabolism. (92) |
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| A cell-like organelle present in algae and plants that contains chlorophyll (and usually other pigments) and is the site of photosynthesis. (92) |
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Definition
| A cell structure composed of protein and RNA that translates RNA copies of genes into protein. (85) |
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Definition
| A fine, long threadlike organelle protruding from the surface of a cell. In bacteria, a single protein fiber capable of rotary motion that propels the cell through the water. In eukaryotes, an array of microtubules with a characteristic internal 9 + 2 microtubule structure that is capable of vibratory but not rotary motion. Used in locomotion and feeding. Common in protists and motile gametes. A cilium is a short flagellum. (95) |
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| Refers to flagella, which are numerous and organized in dense rows. Cilia propel cells through water. In human tissue, they move water or mucus over the tissue surface. (95) |
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Definition
| The net movement of molecules to regions of lower concentration as a result of random, spontaneous molecular motions. The process tends to distribute molecules uniformly. (98) |
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Definition
| The diffusion of water across a membrane that permits the free passage of water but not that of one or more solutes. Water moves from an area of low solute concentration to an area with higher solute concentration. (99) |
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Definition
| A state achieved by a substance where there is no net movement toward any particular direction. (98) |
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| The process by which the edges of plasma membranes fuse together and form an enclosed chamber called a vesicle. It involves the incorporation of a portion of an exterior medium into the cytoplasm of the cell by capturing it within the vesicle. (100) |
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Definition
| The extrusion of material from a cell by discharging it from vesicles at the cell surface. The reverse of endocytosis. (100) |
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| The ability of a cell to control what enters and leaves it across its plasma membrane. (102) |
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| The transport of a solute across a membrane by protein carrier molecules to a region of higher concentration by the expenditure of chemical energy. One of the most important functions of any cell. (103) |
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