| A | B |
|---|
| active transport | process in which a cell uses energy to transport a substance into or out of the cell |
| amino acid | building block of protein |
| asexual reproduction | reproduction requiring only one parent |
| ATP | substance in which cells store energy |
| autotroph | organism that can produce its own food, primarily through photosynthesis |
| carbohydrate | energy-rich substance found in foods such as vegetables, cereal grains, and breads; sugars and starches |
| cell | basic unit of structure and function in living things |
| cell division | process in which one cell divides into two cells, each of which is identical to the original cell |
| cell membrane | thin, flexible envelope that surrounds a cell and allows passage of materials into and out of the cell |
| cell theory | theory that all living things are made of cells, that all cells come from other cells, and that the cell is the basic unit of structure and function in living things |
| cell wall | : outermost boundary of plant cells that is made of cellulose |
| chloroplast | cell organelle containing chlorophyll that is involved in the process of photosynthesis |
| chromatin | threadlike coils of chromosomes |
| chromosome | rod-shaped cell structure that directs the activities of a cell and passes on the traits of a cell to new cells |
| compound | two or more elements chemically combined |
| cytoplasm | region between the cell membrane and the nucleus |
| diffusion | process by which substances move from a higher concentration of that substance to a lower concentration of that substance; primary method by which substances enter and leave the cell through the cell membrane |
| digestion | process by which food is broken down into simpler substances |
| division of labor | division of work among the different parts of an organism's body that keeps an organism alive |
| DNA | nucleic acid that stores the information needed to build proteins and carries genetic information about an organism |
| element | pure substances that cannot be separated into simpler substances by ordinary chemical processes |
| endoplasmic reticulum | tubular passageways in the cell through which substances such as proteins are transported |
| enzyme | chemical substance that helps control chemical reactions |
| excretion | process of getting rid of waste materials |
| fat | substance that supplies the body with energy and also helps support and cushion the vital organs in the body |
| fermentation | energy-releasing process that does not require oxygen; less efficient than respiration |
| heterotroph | organism that cannot make its own food |
| homeostasis | ability of an organism to keep conditions inside its body the same, even though conditions in its external environment change |
| ingestion | taking in food; eating |
| life span | maximum length of time an organism can be expected to live |
| lysosome | small; round structure , in a cell involved in the digestive activities of the cell |
| metabolism | sum total of all chemical activities in an organism |
| mitochondria | power- houses of the cell in which cellular respiration occurs |
| mitosis | process in which the nucleus of a cell divides into two nuclei and the formation of two new daughter cells begins |
| nucleic acid | large, organic compound that stores information that helps the body make the proteins it needs; DNA or RNA |
| nucleus | cell structure that directs all the activities of the cell |
| organ | group of different tissues working together; the third level of organization in an organism |
| organ system | group of organs that work together to perform a specific function for the organism, the fourth level of organization in an organism |
| organelle | "tiny organs" that make up a cell |
| organic compound | compound found in living things that contains the element carbon |
| osmosis | term given for the diffusion of water through a membrane |
| photosynthesis | process by which organisms use energy from sunlight to make their own food |
| protein | substance used to build and repair cells; made up of amino acids |
| respiration | process in which simple food substances such as glucose are broken down and the energy they contain is released |
| response | some action or movement of an organism brought on by a stimulus |
| ribosome | protein-making site of the cell |
| RNA | nucleic acid that "reads" the genetic information carried by DNA and guides the protein-making process |
| selectively permeable | membrane that allows certain materials to pass through, but restricts other materials from passing through |
| sexual reproduction | reproduction usually involving two parents in which a sex cell from each parent unite to form offspring |
| spontaneous generation | hypothesis that states that life can spring from nonliving matter |
| stimulus | signal to which an organism reacts; change in the environment |
| stomata | openings in the lower surface of the epidermis in a green plant that allows gases to enter and leave the plant's cells |
| tissue | group of similar cells that perform a special function in an organism; the second level of organization in an organism |
| vacuole | large, round sac in the cytoplasm of a cell that stores water, food, enzymes, and other materials |
