This tall, branching saguaro cactus provides nesting sites, food, and water to other animals of the Sonoran Desert.
Which term best characterizes the role of the saguaro cactus in its desert
ecosystem?

Biotic factor.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

d. organisms have cells with different shapes and functions.