Advertisement Upgrade to remove ads

Definitions from Module 5# in Apologia Biology.


Anything that has mass and takes up space.


An explanation or representation of something that cannot be seen.


A collection of atoms that all have the same number of protons.


Chemicals that result from atoms linking together.

Physical Change

A change that affects the appearance but not the chemical makeup of a substance.

Chemical Change

A change that alters the makeup of the elements or molecules of a substance.


One of the 3 forms - solid, liquid, or gas - which every substance is capable of attaining.


The random motion of molecules from one area of high concentration to an area of low concentration.

Semipermeable Membrane

A membrane that allows some molecules to pass through but does not allow other molecules to pass through.


The tendency of a solvent to travel across a semipermeable membrane into areas of higher solute concentration.


A substance that alters the speed of a chemical reaction but is not used up in the process.

Organic Molecule

A molecule that contains only carbon and any of the following: hydrogen, oxygen, nitrogen, sulfur, and/or phosphorus


The process by which living organisms produce larger molecules from smaller ones.


Two different molecules that have the same chemical formula.


Simple carbohydrates that contain 3 to 10 carbon atoms.


Carbohydrates that are made up of two monosaccharides.

Dehydration Process

A chemical reaction in which molecules combine by removing water.


Breaking down complex molecules by the addition of water.


Lacking any affinity to water.

Saturated Fat

A lipid made from fatty acids that have no double bonds between carbohydrates.

Unsaturated Fat

A lipid made from fatty acids that have at least one double bond between carbon atoms.

Peptide Bond

A bond that links amino acids together in a protein.

Hydrogen Bond

A strong attraction between hydrogen atoms and certain other atoms in specific molecules.


Carbohydrates that are made up of more than two monosaccharides


A measurment of how much solute exists within a certain volume of solvent

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording