Answer:
The characteristic of most single-celled organisms is that they perform all life processes.
Step-by-step explanation:
Most single-celled organisms, such as bacteria and protists, perform all life processes within a single cell. They do not have specialized tissues or organs like multi-cellular organisms. This means that a single cell must carry out all the functions necessary for life, including obtaining nutrients, excreting waste, and carrying out metabolic reactions.
Single-celled organisms have simpler structures than multi-cellular organisms and do not have circulatory or respiratory systems. While some single-celled organisms can respond to their environment, they do not have complex nervous systems as animals do.