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know these terms for the AP Biology test.


substances that cannot be broken down into simpler substances

trace elements

elements that are required by an organism in small quantities


the smallest unit of an element that retains its characteristic properties


positively charged particles in the nucleus of an atom


uncharged particles in the nucleus of an atom


the core of an atom


negatively charged particles that spin around the nucleus of an atom


atoms with the same number of protons but a different number of neutrons


when two or more different types of atoms are combined in a fixed ration

chemical reaction

when elements combine to form a substance with different properties

chemical bonds

how atoms of a compound are held together

ionic bond

formed between two atoms when one or more electrons are transferred from one atom to the other

covalent bond

when electrons are shared between atoms

nonpolar covalent

if electrons are shared equally between atoms

polar covalent

if electrons are shared unequally between atoms


molecules wit a partially positive charge and a partially negative charge

hydrogen bond

weak chemical bonds that form when a hydrogen atom that is covalently bonded to one electronegative atom is also attracted to another electronegative atom


water molecules like to stick to other substances


water molecules have tendency to stick together

surface tension

water molecules have a tendency to stick together making it difficult to break the surface of water

capillary action

water moves up plant vessels do to cohesion

heat capacity

the ability of a substance to store heat (the quantity of heat required to change the temperature of a substance by 1 degree)


a substance that contains more hydrogen ions than hydroxide ions

basic/ alkaline

a substance that contains more hydroxide ions than hydrogen ions


pH of 7. equal concentration of hydrogen ions and hydroxide ions

organic compounds

molecules with a carbon skeleton

inorganic compounds

molecules that do not contain carbon atoms


a versatile atom with the ability to bind to other atoms as well as atoms of its same kind


organic compounds that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio


a carbohydrate with one sugar molecule


a carbohydrate with two sugar molecules


a carbohydrate with many sugar molecules


a six-carbon monosaccharide with the chemical formula C6H12O6. plants produce it and cells break it down


a six-carbon monosaccharied with the chemical formula C6H12O6, a common sugar in fruits

glycosidic bond

the linking of two glucose molecules by removing a water molecule

dehydration synthesis/condensation

taking away a water molecule to make a bond between two atoms


adding a water molecule to break up two atoms


a molecule with repeating subunits of the same general type


a polysaccharide that plants use to stockpile alpha-glucose


structures made of starch in plants


a polysacchardie made up of beta-glucose that lends structural support to the cell wall in plants


a polysaccharide that allows animals to store glucose molecules in the liver and muscle cells

amino acids

organic molecules that serve as the building blocks of proteins

R group/side chain

the part of an amino acid that differentiates it from other amino acids

functional groups

distinctive groups of atoms that play a large role in determining the chemical behavior of the compound they are a part of


when two amino acids join

peptide bond

the bond between two amino acids by dehydration synthesis


a group of amino acids joined together in a string


forms when a polypeptide chain twists and folds on itself to form a three-dimensional structure


molecules consisting of carbon, hydrogen, and oxygen atoms not in a 1:2:1 ratio, fats, oils, and steroids

neutral fats

consists of three fatty acids and one molecule of glycerol

ester linkage

the forming of a triglyceride by each of the carboxyl groups of three fatty acids reacting with one of the three hydroyl groups of glycerol by dehydration synthesis


a fatty acid that has a single covalent bond between each pair of carbon atoms


a fatty acid with adjacent carbons joined by double bonds instead of single bonds


a fatty acid with many double bonds within the fatty acid


lipids that contain two fatty acid tails and one negatively charged phosphate head


water hating


water loving


a molecule (like a phospholipid) that has a hydrophobic and a hydrophilic region


a lipid with a basic structure of four linked carbon rings


a lipid with a long hydrocarbon chain and a carboxyl group at the end, tend to be solid at room temperature and saturated


a lipid with a long hydrocarbon chain and a carboxyl group at the end, tend to be liquid at room temperature and unsaturated


the head of a triglyceride

nucleic acids

molecules made up of simple units of nucleotides and contain carbon, hydrogen, oxygen, nitrogen and phosphorus


simple units that make up nucleic acids, DNA and RNA

DNA (deoxyribonucleic acids)

contains the hereditary blueprints of all life

RNA (ribonucleic acid)

essential molecule in protein synthesis

Oparin and Haldane

scientists that proposed the primitive atmosphere contained methane, ammonia, hydrogen, and water that combined in a chemical reaction that created organisms

Stanley Miller and Harold Urey

scientists that simulated a primitive atmosphere and proved that life could've developed from nonliving matter


living organisms that rely on organic molecules for food

autotrophs (or producers)

organisms that make their own food

heterotroph hypothesis

the theory that the earliest life forms relied on other organic molecules for energy

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