Which level of organization contains all properties of living things?

The level of organization that contains all properties of living things is the organism. An organism is an individual living entity that can carry out all basic life processes, such as growth, reproduction, metabolism, and response to the environment. Each organism, whether it is a single-celled bacterium or a multicellular animal, exhibits the characteristics that define life, such as maintaining homeostasis, utilizing energy, and responding to stimuli.

The cell is indeed a fundamental unit of life, and it possesses many life characteristics, but it does not encompass the full range of organization and systemic functionality found in an entire organism. Tissues and organs are composed of cells and contribute to the functions of an organism, but they by themselves do not exhibit all the properties of life as a complete and functioning entity does. Thus, while cells, tissues, and organs are essential components, they are part of a larger structure that is the organism, which integrates all these functions at a higher level of organization.