Biology Ch 1-3

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biodiversity

Back 1

the total number of species with in an ecosystem and the resulting complexity of interactions among them.

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cell

Back 2

the smallest unit of life

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community

Back 3

all the interacting opulations within an ecosystem

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conclusion

Back 4

the final operation in the scientific method, a decision made about the validity of a hypothesis on the basis of experimental evidence.

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control

Back 5

the portion of an experiment in which all possible variables are held constant

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DNA

Back 6

(deoxyribonucleic acid) a molecule composed of deoxyribose nucleotides, contains the genetic information of all living cells.

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energy

Back 7

the capacity to do work.

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evolution

Back 8

the descent of modern organisms with modification from preexisting life forms

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experiment

Back 9

the third operation in the scientific method; the testing of a hypothesis by further observations, leading to a conclusion.

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gene

Back 10

a unit of heredity that encodes the information needed to specify the amino acide sequence of proteins and hence particular traits; a functional segment of DNA located at a particular place on a chromosome.

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hypothesis

Back 11

the second operation in the scientific method; a supposition based on previous observations that is offered as an explanation for the observed phenomenon and is used as the basis for further observations or experiments.

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metabolism

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the sum of all chemical reactions that occur within a single cell or within all the cells of a multicellular organism.

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natural selection

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the unequal survival and reproduction of organisms due to envrionmental forces, resulting in the preservation of favorable adaptations.

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observation

Back 14

the first operation in the scientific method; the noting of a specific phenomenon, leading to the formulation of a hypothesis.

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organ

Back 15

a structure (such as the liver, kideny or skin) composed of two or more distinct tissue types that function together.

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organism

Back 16

an individual living thing

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photosynthesis

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the complete series of chemical reactions in which the energy of light is used to synthesize high energy organic molecules, normally carbohydrates, from low energy inorganic molecules, nomrally carbon dioxide and water.

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population

Back 18

all the members of a particular species within an ecosystem, found in the same time and place and actually or potentially interbreeding.

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prediction

Back 19

after hypothesis, typically in "if...then" form. - tested with observations and experiments.

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question

Back 20

after seeing an observation...a question is formed about what was seen

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scientific method

Back 21

a rigorous procedure for making observations of specific phenomena and searching for the order underlying those phenomena, consists of four operations: observation, hypothesis, experiment, and conclusion.

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scientific theory

Back 22

a general explanation of natural phenomena developed through extensive and reproducible observations; more general and reliable than a hypothesis.

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species

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the basic unit of taxonomic classification, consisting of a population or series of populations of clasesly related and similar organisms. interbreed with one another but not with memebers of other species.

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tissue

Back 24

a group of (normally similar) cells that together carry out a specific function, for ex: muscle

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variable

Back 25

a condition, particularly in a scientific experiment, that is subject to change.

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acid

Back 26

a substance that releases hyrdrogen ions (H+) into solution, a solution with a pH of less than 7.

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amino acid

Back 27

the individual subunit of which proteins are made, composed of a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable group of atoms denoted by the letter R.

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atom

Back 28

the smallest particle of an element that retains the properties of the element.

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atomic nucleus

Back 29

the membrane-bound organelle of eukaryotic cells that contains the cell's genetic material.

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atomic number

Back 30

the number of protons in the nuclei of all atoms of a particular element.

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base

Back 31

a substance capable of combining with and neutralizing H+ ions in a solution; a solution with a pH of more than 7

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buffer

Back 32

a compound that minimizes changes in a pH by reversibly taking up or releasing H+ ions.

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carbohydrate

Back 33

a compound composed of carbon, hydrogen, and oxygen, with the approximate chemical formula (ch20); includes sugars and starches.

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chemical bond

Back 34

the force of attraction between neighboring atoms that hold them together in a molecule.

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chemical reaction

Back 35

the process that forms and breaks chemical bonds that hold atoms together.

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cohesion

Back 36

the tendency of molecules of a substance to stick together

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covalent bond

Back 37

a chemical bond between atoms in which electrons are shared.

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dehydration synthesis

Back 38

a chemical reaction in which two molecules are joined by a covalent bond with the simultaneous removal of a hydrogen atom from one molecule and a hydroxyl group from the other, forming water; the reverse of hydrolysis.

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denature

Back 39

the disrupt the secondary and/or tertiary structure of a protein while leaving its amino acide sequence intact. denatured proteins cna no longer perform their bilogical functions.

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electron

Back 40

a subatomic particle, found in an electron shell outside the nucleous of an atom, that bears a unit of negative charge and very little mass.

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electron shell

Back 41

a region within which electrons orbit that corresponds to a fixed energy level at a given distance from the atomic nucleus of an atom.

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element

Back 42

a substance that cannot be broken down, or converted, to a simpler substance by ordinary chemical means.

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functional group

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one of several groups of atoms commonly found in an organic molecule including hydrogen, hydroxyl, amino, carboxyl, and phosphate groups, that determine the characteristics and chemical reactivity of the molecule.

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hydrogen bond

Back 44

the weak attraction between a hydrogen atom that bears a partial positive charge(due to polar covalent bonding with another atom) and another atom, nomrally oxygen or nitrogen, that bears a partial negative charge; hydrogen bonds may form between atoms of a single molecule or of different molecules.

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hydrolysis

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the chemical reaction that breaks a covalent blond by means of the addition of hydrogen to teh atom on one side of the original bonde and a hydroxyl group ot the atom on the other side

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ion

Back 46

a charged atom or molecule, an atom or molecule that either has an excess of electrons or has lost electrons.

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ionic bond

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a chemical bond formed by the electrical attraction between positively and negatively charged ions.

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isotope

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one of several forms of a single element, the nuclei of which contains the same number of protoons but different number of neutrons.

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lipid

Back 49

one of a number of organic molecules containing large nonpolar regions composed solely of carbon and hydrogen, which make lipids hydrophobic and insoluble in water, includes oils, fats, waxes, phopholipids, and steroids.

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molecule

Back 50

a particle composed of one or more atoms held together by chemical bonds; the smallest particle of a compound that displays all the properties of that compound.

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neutron

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a subatomic particle that is found in the nuclei of atoms, bears no charge, and has a mass approximately equal to that of a proton.

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non polar molecule

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a molecule bound by the covalent bonds in which electrical charge is symmetrically distributed, so that no portion of the molecule is electrically charged relative to other portions.

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nucleic acid

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an organic molecule composed of nucleotide subunits; the two common t ypes of nucleic acids are ribonucleic acid (rna) and deoxyribonucleic acid (dna)

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organic molecule

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a molecule that contains both carbon and hydrogen.

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pH Scale

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a scale, with values from 0 to 14, used for measuring the relative acidity of a solution, at pH 7 is neutral, ph 0-7 is acidic, and ph 7 to 14 is basic, each unit on the scale represents a tenfold change in H+ concentration.

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polar molecule

Back 56

a molecule bound by covalent bonds in which electrical charge is symmetrically distributed, so that electrical charge differs in different portions of the molecule.

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protein

Back 57

polymer of amino acids joined by peptide bonds.

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proton

Back 58

a subatomic particle that is found in the nuclei of atoms, bears a unit of positive charge and has a relatively large mass, roughtly equal to the mass of a neutron.

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radioactive

Back 59

pertaining to an atom with an unstable nucleus that spontaneously disintegrates with the emission of radiation.

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solvent

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a liquid capable of dissolving *uniformly dispersing) other substances in itself.

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surface tension

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the property of a liquid to resist penetration by ojects at its interface with the air, due to cohesion between molecules of the liquid.

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wax

Back 62

a lipid composed of fatty acids covalently bonded to long chain alcohols.

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active transport

Back 63

the movement of materials across a membrane through the use of cellular energy, normally against a concentration gradient.

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carrier protein

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a membrane protein that facilitates the diffusion of specific substances across the membrane. the molecule to be transported binds to the outer surface of teh carrier protein; the protein then changes shape, allowing the molecule to move across the membrane through the protein.

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cell wall

Back 65

a layer of material, normally made up of cellulose of cellulose like materials, that is outside the plasma membrane of plants, fungi, bacteria, and some protists.

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channel protein

Back 66

a membrane protein that forms a channel or pore completely through the membrane and that is usually permeable to one or to a few wtaer soluble molecules, especially ions.

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concentration gradient

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the difference in concentration of a substance between two parts of a fluid or across a barrier such as a membrane.

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diffusion

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the net movement of particles from a region of high concentration of that type of particle to a region of low concentration, driven by the concentration gradient, may occur entirely within a fluid or across a barrier such as a membrane

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endocytosis

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the process in which the plasma membrane engulfs extracellular material, forming membrane bound sacs that enter the cyctoplasm and thereby move material into the cell.

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exocytosis

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the process in which intracellular material is enclosed within a membrane bound sac that moves to the plasma membrane and fuses with it, releaseing the material outside the cell.

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facilitated diffusion

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the diffusion of molecules across a membrane, assisted by protein pores or carriers embedded in the membrane.

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fluid mosaic

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a model of membrane structure; according to this model, membranes are composed of a double layer of phospholipids in which various proteins are embedded. the phospholipid bilyaer is a somewhat fluid matrix that allows the movement of proteins within it.

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hydrophilic

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pertaining to a substance that dissolves readily in water or to parts of a large molecule that form hydrogen bonds w water.

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hydrophobic

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pertaining to a substance that does not dissolve in water.

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osmosis

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the diffusion of water acrossa a differentially permeable membrane.

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passive transport

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the movement of materials across a membrane down a gradient of concentration , pressure, or electrical charge without using cellular energy.

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phospholipid bilayer

Back 77

a double layer of phospholipids that form teh basis of all cellular membranes. the phospholipid heads, which are hydrophilic, face the wter of extracellular fluid or the cytoplasm; the tails, which are hydrophobic, are burried in the middle of teh bilayer.

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plasma membrane

Back 78

the outer membrane of a cell, composed of a bilayer of phospholipids in which proteins are embedded.

Front 79

receptor protein

Back 79

a protein, located on a membrane, that recognizes and binds to specific molecules. Binding by receptor proteins typically triggers a response by a cell, such as endocytosis, increased metabolic rate, or cell division.

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recognition protein

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a protein or glycoprotein protruding from the outside surface of a plasma membrane that identifies a cell as belonging to a particular species, to a specific individual of that species, and in many cases to one specific organ within the individual.

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selectively permeable

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refers to membranes across which some substances may pass freely while other substances cannot pass.

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simple diffusion

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the diffusion of water, dissolved gases , or lipid soluble molecules through the phospholipid bilayer of a cellular membrane.

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transport protein

Back 83

a protein that regulates the movement of water soluble molecultes through the plasma membrane.

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vesicle

Back 84

a small, membrane bound sac within the cytoplasm.

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entropy

Back 85

a measure of the amount of randomness and disorder in a system.

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isotonic

Back 86

referring to a solution that has the same concentration of dissolved particles (and therefore the same concentration of free water) as has the cytoplasm of a cell.

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hypotonic

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referring to a solution that has a lower concentration of a dissolved particles (and therefore a higher concentration of free water) than has the cytoplasm of a cell.

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hypertonic

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referring to a solution that has a higher concentration of dissolved particles (and therefore a lower concentration of free water) than has the cytoplasm of a cell.

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turgor pressure

Back 89

pressure developed within a cell (especially the central vacuole of plant cells) as a result of osmotic water entry.