Biology: Chapter 2

Question 1

atom

Answer 1

smallest basic unit of matter

Question 2

element

Answer 2

one particular type of atom and cannot be broken down into a simpler substance by ordinary chemical means

Question 3

compound

Answer 3

substance made of atoms of different elements bonded together in a certain ratio

Question 4

ion

Answer 4

an atom that has gained or lost one or more electrons

Question 5

ionic bond

Answer 5

bond that forms through electrical for between oppositely charged ions

Question 6

covalent bond

Answer 6

bond that forms when atoms share a pair of electrons

Question 7

molecule

Answer 7

two or more atoms held together by a covalent bond

Question 8

hydrogen bond

Answer 8

an attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or nitrogen

Question 9

cohesion

Answer 9

the attraction among molecules

Question 10

adhesion

Answer 10

attraction among molecules of different substances

Question 11

solution

Answer 11

a mixture of substances that is the same throughout (homogenous mixture)

Question 12

solvent

Answer 12

the substance in a solution that is present in the greater amount and that dissolves another substance

Question 13

solute

Answer 13

a substance that is being dissolved in a solvent

Question 14

acid

Answer 14

a compound that releases a proton -a hydrogen ion (H+)- when it dissolves in water

Question 15

base

Answer 15

compound that removes H+ ions from a solution

Question 16

pH

Answer 16

scale to measure a solution’s acidity, or H+ ion concentration

Question 17

monomer

Answer 17

subunit in the complete molecule of carbon-based molecules

Question 18

polymer

Answer 18

large molecule, or macromolecule , made of many monomers bonded together

Question 19

carbohydrates

Answer 19

molecules composed of carbon, hydrogen, and oxygen, and include sugars and starches

Question 20

lipid

Answer 20

nonpolar molecules that include fats, oils, and cholesterol

Question 21

fatty acids

Answer 21

chains of carbon atoms bonded to hydrogen atoms

Question 22

protein

Answer 22

polymer made of monomers called amino acids

Question 23

amino acids

Answer 23

molecules that contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur

Question 24

nucleic acids

Answer 24

polymers that are made up of monomers called nucleotides

Question 25

chemical reaction

Answer 25

event that changes a substance into different substances by breaking down and forming chemical bonds

Question 26

reactants

Answer 26

substances changed during a chemical reaction

Question 27

products

Answer 27

substances made by a chemical reaction

Question 28

bond energy

Answer 28

amount of energy that will break a bond between two atoms

Question 29

equilibrium

Answer 29

when both reactants and products are made at the same rate

Question 30

activation energy

Answer 30

amount of energy that needs to be absorbed for a chemical reaction to start

Question 31

exothermic

Answer 31

chemical reaction that releases more energy that it absorbs

Question 32

endothermic

Answer 32

chemical reaction that absorbs more energy that it releases

Question 33

catalyst

Answer 33

substance that decreases the activation energy needed to start a chemical reaction and increases the rate of the chemical reaction

Question 34

enzyme

Answer 34

catalysts for chemical reactions in living things

Question 35

substrate

Answer 35

specific reactants that an enzyme acts on