Biology Marking Period 3 Practice Test

An organism is a living thing—the individual that carries out all the basic life processes. This includes metabolism, growth, reproduction, response to stimuli, and maintaining internal balance. A group of organs is an organ system, not the whole being. A tissue is a group of similar cells performing a function, and a cell is the basic unit of life (though an entire single cell can be an organism in unicellular life). In multicellular organisms, many cells come together to form tissues, organs, and organ systems that together make up one organism. So the best description is that an organism is a living thing.