<span>Its not actually just one system if you look at it, there are various interdependent system that actually manages every movement of every system in order to maintain homeostasis, plainly every set function is a coordinated body system response. For example, the digestive system digests food because of the enzymes and the cells and organs present in its system but again, this is aided by the different hormones which is part of the endocrine system, interdependently. Thus eventually, the circulatory system is the organ system that intiates in dissemination of the different processed and intially metabolized nutrients in the digestive system and sent throughout the body. Incidentally, also the immune system acts as agent in again many systems to maintain the so-called homeostasis. </span>
True rainforests cover less than 2 percent of the earths total surface
The correct answer is letter A: the circulatory system removes waste from the tissues by converting carbon dioxide-rich blood into oxygen-rich blood that can be circulated throughout the body to support its several functions. Without the lungs the human body will not be able to process converting blood cells into oxygen-rich cells in the body.
Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
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