Organisms may contain up to five levels of organization within their bodies. Which level of organization is best represented by the liver?
tissue
organ
organism
organ system

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?

Control of the body is accomplished by which of the following body systems? nervous system and circulatory system endocrine and repertory system circulatory and respiratory systems nervous system and endocrine systems

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?