ACT Science Vocabulary(Science Vocabulary Word to
study for the ACT)
Absolute zero Correct Answer: Approximately -273° C; the lowest possible
temperature
Acid Correct Answer: A compound that releases hydrogen ions when dissolved in
water; has a pH of less than 7
Algae Correct Answer: Simple, one-celled plantlike organism found in water or
damp places; includes seaweeds, pond scum, and so on
Alloy Correct Answer: A substance composed of two or more metals
Atmosphere Correct Answer: The layer of air surrounding Earth
Atmospheric pressure Correct Answer: The pressure exerted by the atmosphere on
every part of Earth's surface; approximately 10 newtons per square centimeter
Atom Correct Answer: The smallest part of an element that is recognizable as that
element
Barometer Correct Answer: An instrument that measures atmospheric pressure
Base Correct Answer: A compound that releases hydroxide ions in water; has a
pH of more than 7; is sometimes called an alkali
Boiling point Correct Answer: The temperature at which additional thermal
energy causes a substance to change from a liquid to a vapor
Calorie Correct Answer: A quantity of heat energy; the amount needed to raise the
temperature of one gram of water 1° C
Carbohydrate Correct Answer: An organic compound-like sugar or starch that
contains carbon, hydrogen, and oxygen in the ratio of 1:2:1; the human body's
main source of energy
Carcinogen Correct Answer: A cancer-causing agent
, Carnivore Correct Answer: Meat-eater
Catalyst Correct Answer: A substance that speeds up a chemical reaction without
being changed by the reaction
Cell Correct Answer: The lowest-level structure of any living organism that can
perform all the functions of life, including reproduction
Chlorophyll Correct Answer: The main pigment in plants that captures light
energy during photosynthesis
Compound Correct Answer: A substance composed of two or more chemically
bonded elements
Concentration Correct Answer: The exact amount of substance dissolved in a
given amount of solvent; refers to a solution
Condensation Correct Answer: The process whereby a decrease in energy causes
vapor particles to return to a liquid phase
Conductor Correct Answer: A material that allows heat or electricity to flow
through it with minimal resistance
Control Correct Answer: A sample in which no variables are tested, thus serving
as a basis for comparison
Control variable Correct Answer: A variable that stays constant in an experiment,
allowing the effect of another variable to be measured
Convection Correct Answer: The circulation of fluid caused by warm fluid rising
and cool fluid sinking
Density Correct Answer: In a physics sense, the amount of mass per unit volume;
in a more general sense, the quantity per unit area or volume
Diffusion Correct Answer: The scattering of light; the spreading of a liquid or gas
from areas of higher concentration to areas of lower concentration
DNA Correct Answer: Nucleic acid in the cells of an organism; contains the genes
of an organism and transmits these to future generations
study for the ACT)
Absolute zero Correct Answer: Approximately -273° C; the lowest possible
temperature
Acid Correct Answer: A compound that releases hydrogen ions when dissolved in
water; has a pH of less than 7
Algae Correct Answer: Simple, one-celled plantlike organism found in water or
damp places; includes seaweeds, pond scum, and so on
Alloy Correct Answer: A substance composed of two or more metals
Atmosphere Correct Answer: The layer of air surrounding Earth
Atmospheric pressure Correct Answer: The pressure exerted by the atmosphere on
every part of Earth's surface; approximately 10 newtons per square centimeter
Atom Correct Answer: The smallest part of an element that is recognizable as that
element
Barometer Correct Answer: An instrument that measures atmospheric pressure
Base Correct Answer: A compound that releases hydroxide ions in water; has a
pH of more than 7; is sometimes called an alkali
Boiling point Correct Answer: The temperature at which additional thermal
energy causes a substance to change from a liquid to a vapor
Calorie Correct Answer: A quantity of heat energy; the amount needed to raise the
temperature of one gram of water 1° C
Carbohydrate Correct Answer: An organic compound-like sugar or starch that
contains carbon, hydrogen, and oxygen in the ratio of 1:2:1; the human body's
main source of energy
Carcinogen Correct Answer: A cancer-causing agent
, Carnivore Correct Answer: Meat-eater
Catalyst Correct Answer: A substance that speeds up a chemical reaction without
being changed by the reaction
Cell Correct Answer: The lowest-level structure of any living organism that can
perform all the functions of life, including reproduction
Chlorophyll Correct Answer: The main pigment in plants that captures light
energy during photosynthesis
Compound Correct Answer: A substance composed of two or more chemically
bonded elements
Concentration Correct Answer: The exact amount of substance dissolved in a
given amount of solvent; refers to a solution
Condensation Correct Answer: The process whereby a decrease in energy causes
vapor particles to return to a liquid phase
Conductor Correct Answer: A material that allows heat or electricity to flow
through it with minimal resistance
Control Correct Answer: A sample in which no variables are tested, thus serving
as a basis for comparison
Control variable Correct Answer: A variable that stays constant in an experiment,
allowing the effect of another variable to be measured
Convection Correct Answer: The circulation of fluid caused by warm fluid rising
and cool fluid sinking
Density Correct Answer: In a physics sense, the amount of mass per unit volume;
in a more general sense, the quantity per unit area or volume
Diffusion Correct Answer: The scattering of light; the spreading of a liquid or gas
from areas of higher concentration to areas of lower concentration
DNA Correct Answer: Nucleic acid in the cells of an organism; contains the genes
of an organism and transmits these to future generations
