bio exam 1 vocab

biology

the branch of science that is concerned with the study of life and living organisms

atoms

smallest particle of an element that displays the properties of the element

molecules

union of two or more atoms of the same element; also, the smallest part of a compound that retains the properties of the compound

cell

the smallest unit of life that displays all the properties of life; composed of cytoplasm surrounded by a plasma membrane

population

group of organisms of the same species occupying a certain area and sharing a common gene pool

species

group of similarly constructed organisms capable of interbreeding and producing fertile offspring; organisms that share a common gene pool

community

assemblage of species interacting with one another within the same environment

ecosystem

biological community together with the associated abiotic environment; characterized by a flow of energy and a cycling of inorganic nutrients

biosphere

zone of land, air, and water at the surface of the earth in which living organisms are found

energy

capacity to do work and bring about change; occurs in a variety of forms

metabolism

the sum of the chemical reactions that occur in a cell

homeostasis

maintenance of normal internal conditions in a cell or an organism by means of self-regulating mechanisms

genes

unit of heredity existing as alleles on the chromosomes; in diploid organisms, typically two alleles are inherited- one from each parent

evolution

genetic change in a species over time, resulting in the development of genetic and phenotypic differences that are the basis of natural selection; descent of organisms from a common ancestor.

natural selection

mechanism of evolution change caused by environmental selection of organisms that have heritable variation and compete for resources, and are thus most fit to reproduce; results in adaptation to the environment

hypothesis

supposition established by reasoning after consideration of available evidence; it can be tested by obtaining more data, often by experimentation

experiment

a test of a hypothesis that examines the influence of a single variable. often involves both control and test groups

independent variable

experimental variable; factor of the experiment being tested

dependent variable

responding variable; result or change that occurs due to the experimental variable.

matter

anything that takes up space and has mass

elements

substance that cannot be broken down into substances with different properties; composed of only one type of atom

atoms

smallest particle of an element that displays the properties of the element

atomic number

number of protons within the nucleus of an atom

mass number

mass of an atom equal to the number of protons plus the number of neutrons within the nucleus

isotopes

atoms of the same element having the same atomic number but a different mass number due to a variation in the number of neutrons

atomic mass

average of atom mass units for all the isotopes of an atom

molecule

union of two or more atoms of the same element; also, the smallest part of a compound that retains the properties of the compound

compound

substance having atoms of two or more different elements in a fixed ratio

ionic bond

chemical bond in which ions are attracted to one another by opposite charges

covalent bond

chemical bond in which atoms share one or more pairs of electrons

non-polar covalent bond

bond in which the sharing of electrons between atoms is fairly equal

polar covalent bond

bond in which the sharing of electrons between atoms is unequal

hydrogen bonds

weak bonds that arises a slightly positive hydrogen atom of one molecule and a slightly negative atom of another molecule or between parts of the same molecule

heat capacity

organic molecule

functional group

specific cluster of atoms attached to the carbon skeleton of organic molecules that enters into reactions and behaves in a predictable way

isomers

molecules with the same molecular formula but a different structure, and therefore a different shape

polymers

macromolecule consisting of covalently bonded monomers

monomer

small molecule that is a subunit of a polymer

dehydration reaction

chemical reaction in which a water molecule is released during the formation of a covalent bond

hydrolysis reaction

splitting of a chemical bond by the addition of water, with the H+ going to one molecule and the OH- going to the other

carbohydrates

class of organic compounds that typically contain carbon, hydrogen, and oxygen in a 1:2:1 ratio; includes the monosaccharides, disaccharides, and polysaccharides

monosaccharides

simple sugar; a carbohydrate that cannot be broken down by hydrolysis

glycogen

storage polysaccharide found in animals; composed of glucose molecules joined in a linear fashion but having numerous branches

cellulose

polysaccharide that is the major complex carbohydrate in plant cell walls

chitin

strong but flexible nitrogenous polysaccharide found in the exoskeleton of arthropods and in the cell walls of fungi

peptidoglycan

polysaccharide that contains short chains of amino acids found in bacterial cell walls

lipids

class of organic compounds that tend to be soluble in nonpolar solvents; includes fats and oils

saturated fatty acids

fatty acid molecule that lacks double bonds between the carbons of its hydrocarbon chain. the chain bears the maximum number of hydrogens possible

unsaturated fatty acid

fatty acid molecule that contains double bonds between some carbons of its hydrocarbon chain; contains fewer hydrogen

phospholipid

molecule that forms the bilayer of the cell’s membranes; has a polar, hydrophilic head bonded to two nonpolar, hydrophobic tails

protein

polymer of amino acids often consisting of one or more polypeptides and having a complex three-dimensional shape

amino acid

organic molecule composed of an amino group and an acid group; covalently bonds to produce peptide molecules

peptide bond

type of covalent bond that joins two amino acids

peptide

two or more amino acids joined together by covalent bonding

polypeptide

polymer of many amino acids linked by peptide bonds

DNA (deoxyribonucleic acid)

nucleic acid polymer produced from covalent bonding of nucleotide monomers that contain the sugar deoxyribose; the genetic material of nearly all organisms

RNA (ribonucleic acid)

nucleic acid produced from covalent bonding of nucleotide monomers that contain the sugar ribose

nucelotide

monomer of DNA and RNA consisting of a 5-carbon sugar bonded to a nitrogenous base and a phosphate group