Complete each statement about the permeable nature of the plasma membrane by selecting the appropriate term from each dropdown list.

1. The plasma membrane is [semipermeable], meaning that some molecules can cross through it while others cannot.
2. Some smaller, non-charged substances, such as carbon dioxide, are able to diffuse through the membrane without expending any energy.
3. This is called [passive transport] and can make use of [channel proteins] or carrier proteins.
4. Other larger, charged substances, such as macromolecules, aren't able to diffuse through the membrane without expending any energy.
5. This is called [active transport] and can make use of carrier proteins among others.