An ​ (a)   molecule is made up of the base adenine, a ribose sugar, and three phosphate groups. Breaking of the bond between the second and third phosphate groups of an ​ (b)   molecule releases usable energy and forms an ​ (c)   molecule.

The movement of substances across the ____ ________ can occur without an input of energy (passive transport) or require the cell to expend energy (active transport).

(a)  

___________ is the process by which the plasma membrane of a cell surrounds and takes in material. White blood cells engulf harmful cells through ___________. Unicellular organisms such as amoeba absorb their food through ___________. Three types of ___________ include phagocytosis, pinocytosis, and receptor-aided ___________.

(a)  

​ (a)   is the reverse process of ​ (b)   . Cells use ​ (c)   to expel waste matter and to secrete substances, such as hormones.

Some molecules can diffuse across the membrane directly. Other molecules cannot; because they are either too large, charged, or polar. Molecules that cannot cross the membrane directly can diffuse across the membrane with the help of transport proteins. This process is called ​ (a)   .

(a)   is a form of passive transport. It is the diffusion of water through a semi-permeable membrane from an area of high water concentration to an area of low water concentration. Depending on the concentration of water in the surrounding environment, the cells may retain, lose, or gain water, causing the cell to swell, shrink, or remain the same size.

Diffusion and osmosis are both forms of _______ _________.

(a)  

By ​ (a)   , the membrane of a cell allows passage of specific molecules, enabling homeostasis. ​ (b)   is facilitated by membrane molecules and enables the cell to regulate its internal environment.

(a)   proteins move materials across membranes; transport vesicles move materials within the cell. Proteins made in the rough ER are transported to the Golgi in a transport vesicle. The Golgi then modifies the proteins and repackages them into another transport vesicle before sending them out of the cell.