Describe a situation in which specific organisms or objects have unique rolls in a system

Which of the organisms listed below performs nitrogen fixation? a. legumes b. plants c. bacteria d. fungi

Which best describes the scientific method? a. a path of clearly defined steps that must be followed in a particular order b. a possible answer to a scientific question based on knowledge or research c. the recipe for how to conduct an experiment that must be followed precisely d. the process of hypothesis and testing through which scientific inquiry occurs

During convection, less dense fluid rises and denser fluid sinks.