| A | B |
|---|
| organism | A living thing. |
| cell | The basic unit of structure and function in living things |
| organelle | A tiny cell structure that carries out a specific function within the cell. |
| cell membrane | The outside boundary of a cell; controls which substances can enter or leave the cell. |
| cell wall | A rigid layer of nonliving material that surrounds the cells of plants and some other organisms. |
| cytoplasm | The region of a cell located inside the cell membrane (in prokaryotes) or between the cell membrane and nucleus (in eukaryotes); contains a gel-like material and cell organelles. |
| chloroplast | A structure in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food. |
| endoplasmic reticulum | A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another. |
| nucleus | The control center of a cell that directs the cell’s activities; contains the chemical instructions that direct all the cell’s activities and determine the cell’s characteristics. |
| mitochondrion | Rod-shaped cell structures that produce most of the energy needed to carry out the cell’s functions |
| vacuole | A water-filled sac inside a cell that acts as a storage area |
| prokaryote | An organism whose cells lack a nucleus and some other cell structures. |
| eukaryote | An organism with cells that contain nuclei and other cell structures. |
| microscope | An instrument that makes small objects look larger. |
| autotroph | An organism that makes its own food. |
| heterotroph | An organism that cannot make its own food. |
| unicellular | A type of organism that is made up of a single cell. |
| multicellular | A type of organism that is made up of many cells. |
| homeostasis | The process by which an organism’s internal environment is kept stable in spite of changes in the external environment. |
