Biology Unit One Test Concepts

exothermic

releases heat energy

endothermic

takes in/absorbs heat

denature

when a protein unfolds, loses its function

DNA

A genetic code written in a molecule that stores the complex information organisms need to live, grow, and reproduce

stimulus

A signal to which an organism responds

sexual reproduction

Cells from 2 parents unite to form the first cell of a new organism (most plants and animals follow this process)

asexual reproduction

when a single organism produces offspring identical to itself (bacteria and viruses follow this process)

homeostasis

the condition of keeping an organism’s internal environment relatively stable

metabolism

the combination of chemical reactions through which an organism builds up or breaks down materials

prokaryotes

single celled organisms without a nucleus

eukaryotes

organisms with cells that contain a nucleus

archaea

“ancient” bacteria that can live in extreme conditions

eubacteria

“true” bacteria (prokaryote)

autotroph

organism that makes its own food

heterotroph

organism that cannot make its own food and relies on other substances

atom

the basic unit of matter

protons

have the same mass as neutrons, are positively charged, are found in the nucleus

neutrons

have the same mass as protons, have no charge, are found in the nucleus

electrons

negatively charged, are in constant motions in the space surrounding the nucleus attracted to the positively charged nucleus, remain outside due to the energy of their motion

chemical element

a pure substance that consists of entirely one atom

atomic number

the number of protons in the nucleus

isotopes

atoms of the same element that differ in the number of neutrons they contain (same proton number)

mass number

the total number of protons and neutron in the nucleus of an atom

radioactive isotopes

when the nuclei are unstable and break down at a constant rate over time

chemical compound

a substance formed by the chemical combination of two or more elements

chemical formula

the composition of compounds by a kind of shorthand

valence electrons

the electrons that lie on the outermost ring, available to form bonds

ionic bond

formed when one or more electrons are transferred from one atom to another

ion

positively and negatively charged atoms

Van der Waals forces

the slight attraction developed between regions in a covalent bond that has a tiny positive or negative charge

covalent bond

when the electrons between atoms are being shared, travelling around the nuclei of both

molecule

the structure that results when atoms are joined together by a covalent bond; the smallest unit of most compounds

nucleus

contains protons and neutrons, the center of an atom

shells

the areas around the nucleus that contain electrons

atomic mass

the mass of the nucleus

electronegativity

how strongly an atom attracts electrons in a bond

hydrogen bond

the attraction between a partially negative charged hydrogen atom and a partially positively charged hydrogen atom

polarity

when the charges of a molecule are unevenly distributed

cohesion

an attraction between molecules of the same substance

adhesion

an attraction between molecules of different substances

capillary action

the process of liquid flowing in a narrow space without assistance

heat capacity

the amount of heat energy required to increase temperature

mixture

a material composed of two or more elements or compounds that are mixed together, but not chemically combined

solutions

contain a solute and solvent, all the components of it are evenly distributed

solute

substance that is dissolved

solvent

substance in which the solute dissolves

suspensions

mixtures of water and non-dissolved material

pH scale

a measurement system used to indicate the concentration of H+ ions in solutions

acid

any compound with H+ ion in solution

base

a compound that produces hydroxide (OH-) in solution

buffers

weak acids or bases that can react with strong acids or bases to prevent shar, sudden changes in pH

surface tension

intermolecular attractions between water molecules that create a resistance on the surface (ex. a paperclip floating on top of water)

aqueous solution

a solution in which the solvent is water

pH

it is said to stand for “potential of hydrogen”

organic chemistry

the study of compounds that contain bonds between carbon atoms

inorganic chemistry

the study of all compounds other than carbon atoms

macromolecules

large molecules made from many smaller molecules

polymerization

a process in which large compounds are built by joining smaller ones together

monomers

the smaller compounds that are joined to form polymers

polymers

the structures made from polymerization; made up of chains of monomers

carbohydrates

compounds made up of carbon, hydrogen, and oxygen atoms, usually in a 1:2:1 ratio

monosaccharides

simple sugar molecules

disaccharide

a compound made by joining two simple sugars together

polysaccharides

a large carbohydrate molecule

lipids

made mostly of carbon and hydrogen atoms, common categories: fats, oils, and waxes, used to store energy.

saturated lipid

when each carbon in a lipid’s fatty acid chain is joined to another carbon atom by a single bond (contains max number of hydrogen atoms)

unsaturated lipid

when there is at least one carbon-carbon double bond in a fatty acid

polyunsaturated lipid

lipids whose fatty acids contain more than one double bond

nucleic acids

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus, they are polymers assembled from individual monomers known as nucleotides

proteins

macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen, polymers of molecules called amino acids.

amino acids

compounds with an amino group on one end and a carboxyl group on the other end

peptide bonds

link amino acids together to form a polypeptide

chemical reaction

a process that changes, or transforms, one set of chemicals into another (nothing is taken away or added)

reactants

the elements or compounds that enter into a chemical reaction

products

the elements or compounds produced by a chemical reaction

activation energy

the energy needed to get a reaction started

catalyst

speeds up the rate of a chemical reaction (works by lowering a reaction’s activation energy)

enzymes

proteins that act as biological catalysts (speed up the chemical reactions that take place in cells)

substrates

the reactants of enzyme-catalyzed reactions

endergonic

requires energy to react

exergonic

exerts energy (comes out of a reaction)

hypothesis

states the expectations, often using”if” and “then”

independent variable

a variable that stands alone and isn’t changed

dependent variable

a variable that depends on other factors

controlled variables

a variable in an experiment that is unchanged or constant

experimental group

the group that receives the variable being tested in an experiment

control group

a group in the experiment which the variable is not being tested

ATP

energy that is usable in cells

response

action or behavior prompted by stimulus