AP Biology

matter

organisms are composed of ___

compound

a ___ is a substance consisting of two or more different elements in a fixed ratio

emergent properties

a compound has chemical & physical characteristics different than those of its constituent elements; these are ___

essential elements

of the 92 natural elements, about 20-25% are ___ that an organism needs to live a healthy life & reproduce

trace elements

are required by an organism in only minute quantities

atom

an ___ is the smallest unit of matter that still retains the properties of an element

subatomic particles

atoms are composed of even smaller parts, called ___

protons

have one unit of positive charge

electrons

have one unit of negative charge

neutrons

are electrically neutral

atomic nucleus

protons & neutrons are packed together tightly in a dense core, or ___

dalton

for atoms & subatomic particles, we use a unit of measurement called the ___

atomic number

all atoms of a particular element have the same number of protons in their nuclei; this is called the ___

mass number

the ___ is the total number of protons & neutrons in the nucleus of an atom

atomic mass

the mass number is close to, but slightly different from, the total mass of an atom, called its ___

isotopes

some atoms have more neutrons than other atoms of the same element, & thus have greater mass; these are called ___ of the element

radioactive isotope

a ___ is one in which the nucleus decays spontaneously, giving off particles & energy

energy

defined as the capacity to cause change

potential energy

the energy that matter possesses because of its location and structure

electron shells

electrons are found in different ___, each with a characteristic average distance & energy level

periods

the elements are arranged in different rows, or ___ on the periodic table of elements

outermost

the chemical behavior of an atm depends mostly on the number of electrons in its ___ shell

valence electrons

outer electrons are called ___

valence shell

the outermost electron shell is called the ___

inert

an atom with a completed valence shell is unreactive, or ___

chemical bonds

sharing or transferring usually results in atoms staying close together, held by attractions called ___

covalent bond

a ___ is the sharing of a pair of valence electrons by two atoms

molecule

two or more atoms held together by covalent bonds constitute a

single bond

by sharing one pair of valence electrons, the atoms are thus joined by a ___

double bond

by sharing two pair of valence electrons, the atoms are thus joined by a ___

valence

the bonding capacity of an atom is called its ___, & usually equals the number if electrons required to complete the atom’s outermost (valence) shell

electronegativity

the attraction of a particular atom for the electrons of a covalent bond is called ___

nonpolar covalent bond

in covalent bond between two atoms of the same element, the electrons are shared equally because the two atoms have the same electronegativity; this is a ___

ions

in some cases, two atoms are so unequal in their attraction for valence electrons that the more electronegative atom strips an electron completely from its partner; the two resulting oppositely charged atoms (or molecules) are called ___

cation

a positively charged ion is called a ___

anion

a negatively charged ion is called an anion

ionic bonds

because of their opposite charges, cations & anions attract each other; this attraction is called an ___

ionic compounds

compounds formed by ionic bonds are called ___

hydrogen bond

when a hydrogen atom is covalently bonded to an electronegative atom, the hydrogen atom has a partial positive charge, that allows it to be attracted to a different electronegative atom nearby; this is called a ___

chemical reactions

the making and breaking of chemical bonds, leading to changes in the composition of matter, are called ___

reactants

in a chemical reaction, the starting materials are called ___

products

in a chemical reaction, the resulting materials are called ___

chemical equilibrium

as products accumulate, collisions resulting in the reverse reaction become more frequent, the point at which the reactions offset each other exactly is called ___

polar molecule

the unequal sharing of electrons and water’s V-like shape make it a ___, meaning that its overall charge is unevenly distributed

cohesion

collectively, the hydrogen bonds hold the substance together, a phenomenon called ___

adhesion

the clinging of one substance to another

surface tension

a measure of how difficult it is to stretch or break the surface of water

kinetic energy

anything that moves has ___, the energy of motion

thermal energy

the kinetic energy associated with the random movement of atoms or molecules is called ___

temperature

represents the average kinetic energy of the molecules in a body of matter

heat

thermal energy in transfer from one body of matter to another is defined as ___

specific heat

the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1C

evaporative cooling

as a liquid evaporates, the surface of the liquid that remains behind cools down; this is ___

solution

a liquid that is a completely homogenous mixture of two or more substances is called a ___

solvent

the dissolving agent of a solution is the ___

solute

the substance that is dissolved is called the solute

aqueous solution

in which the solute is dissolve in water

hydrophilic

any substance that has an affinity for water is said to be ___

hydrophobic

substances that are nonionic & nonpolar repel water; the substances are said to be ___

hydrogen ion

when a hydrogen atom leaves its electron behind, what is actually transferred if a ___, a single proton with a charge of 1⁺

hydroxide

a water molecule tha loses a proton is a ___ ion, which has a charge of 1^-

acid

a substance that increases the hydrogen ion concentration of a solution

base

a substance that reduces the hydrogen ion concentration of a solution

organic compound

a compound containing carbon is said to be an ___

macromolecules

carbohydrates, proteins, & nucleic acids are called ___

hydrocarbons

organic molecules consisting of only carbon & hydrogen

isomers

compounds that have the same number of atoms of the same element but different structures & hence different properties

structural isomers

isomers that differ in the covalent arrangements of their atoms

cis-trans isomers

in ___, carbons have covalent bonds to the same atoms, but the atoms differ in their spatial arrangements due to the inflexibly of double bonds

enantiomers

isomers that are mirror images of each other & that differ in shape due to the presence e of an asymmetric carbon, one that is attached to four different atoms or groups of atoms

functional groups

certain chemical groups affect molecular function by being directly involved in in chemical reactions ; these important chemical groups are known as ___

adenosine triphosphate (ATP)

consists of an organic molecule called adenosine attached to a string of three phosphate groups

polymer

a long molecule consisting of many similar or identical building blocks linked by covalent bonds

monomers

the repeating units that serve as the building blocks of a polymer are smaller molecules called ___

dehydration reaction

when a water molecule is lost in a reaction

hydrolysis

polymers are disassembled to monomers by ___, a process that is essentially the reverse of a dehydration reaction

carbohydrates

macromolecule that includes both sugars & polymers of sugars

monosaccharides

the simplest carbohydrates are the ___, or simple sugars; these are monomers from which more complex carbohydrates are built

disaccharides

double sugars, consisting of two monosaccharides joined by a covalent bond

glycosidic linkage

a covalent bond formed between two monosaccharides by a dehydration reaction

polysaccharides

polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages

starch

plants store ___, a polymer of glucose monomers, as granules within cells

glucose

the most common monosaccharide, it is of central importance to the chemistry of life

glycogen

animals store a polysaccharide called ___, a polymer that is like amylopectin but more extensively branched

cellulose

a major component of the tough walls that encloses plant cells

fat

consists of a glycerol molecule joined to three fatty acids

saturated fatty acid

fatty acid with as many hydrogens as possible

unsaturated fatty acid

fatty acid with double bonds and fewer hydrogens

trans fats

unsaturated fats that have been synthetic all converted to saturated fats by adding hydrogen

phospholipids

similar to a fat molecule but only has two fatty acids attached to a glycerol rather than three

steroids

lipids characterized by a carbon skeleton consisting of four fused rings

cholesterol

a crucial steroid in animal cell membranes & is also the precursor from which other steroids are synthesized

catalysts

chemical agents that selectively speed up chemical reactions without being consumed in the reaction

peptide bond

the bond between amino acids is called a ___

polypeptide

a polymer of amino acids is called a ___

protein

a biologically functional molecule made up on one or more polypeptides folded & coiled into a specific three-dimensional structure

amino acid

an organic molecule with both an amino group & a carboxyl group

primary structure of a protein

linear chain of amino acids

secondary structure of a protein

regions stabilized by hydrogen bonds between atoms of the polypeptide backbone

alpha helix

secondary structure of DNA in which***