Cells are filled with a gel-like substance called (a)   .

(a)   is the genetic code for all life.

(a)   are molecules that produce proteins.

All cells are surrounded by a protective barrier called a (a)   .

Only (a)   have a cell wall.

The smallest unit of life that can independently reproduce itself is called a (a)   .

DNA is found inside a cell's (a)   .

The human body is a (a)   organism because it is made of trillions of cells.

(a)   create usable energy by combining food with oxygen.