The tendency of a system, especially the physiologicalsystem of higher animals, to maintain internal stability, owingto the coordinated response of its parts to any situation orstimulus that would tend to disturb its normal condition orfunction.
Any cellular organism that has no nuclear membrane, no organellesin the cytoplasm except ribosomes, and has its genetic material inthe form of single continuous strands forming coils or loops,characteristic of all organisms in the kingdom Monera, as thebacteria and blue-green algae.
Any of two or more forms of a chemical element, having the samenumber of protons in the nucleus, or the same atomic number, buthaving different numbers of neutrons in the nucleus, or differentatomic weights. There are 275 isotopes of the 81 stable elements, in addition to over 800 radioactive isotopes, and every elementhas known isotopic forms. Isotopes of a single element possess almost identical properties.
Any alteration in the structure or function of anorganism or any of its parts that results from naturalselection and by which the organism becomes betterfitted to survive and multiply in its environment.
The smallest physical unit of an elementor compound, consisting of one or more like atoms in anelement and two or more different atoms in a compound.
Something made by reproducing an original; copy
The set of nongenetic traits, qualities, or features thatcharacterize a person or thing
A usually microscopic structure containing nuclearand cytoplasmic material enclosed by a semipermeablemembrane and, in plants, a cell wall; the basic structural unitof all organisms.
Having or consisting of a single cell.
A system formed by the interaction of a community of organismswith their environment.
The sum of the physical and chemicalprocesses in an organism by which its material substance isproduced, maintained, and destroyed, and by which energyis made available.
12 Covalent bond
The bond formed by the sharing of a pair of electrons by twoatoms.
One of a class of substances that cannot beseparated into simpler substances by chemical means.
An elementaryparticle that is a fundamental constituent of matter, havinga negative charge and existing independently or as the component outside the nucleus of an atom.
Of or pertaining to the pole of a cell
A pure substance composed of two or moreelements whose composition is constant.
The symbol for the logarithm of the reciprocal of hydrogen ionconcentration in gram atoms per liter, used to express the acidityor alkalinity of a solution on a scale of 0 to 14, where less than 7represents acidity, 7 neutrality, and more than 7 alkalinity.
An organism, usually an animal that feeds on plantsor other animals.
An electrically charged atom or group of atoms formed bythe loss