Answer:
2.7 billion
Explanation:
This period is referred to as the Great Oxygenation Event. This period saw the evolution of photosynthetic organisms (cyanobacteria) that utilized carbon dioxide (that dominated the atmosphere then) and sunlight to manufacture their energy molecules-glucose. Photosynthesis produces oxygen as a byproduct that is evolved into the atmosphere. As these photosynthetic organisms proliferated on earth, the atmosphere composition changed to become partly dominated by oxygen (which is an oxidaton agent) with less and less carbon dioxide.
The neuroendocrine system produces and releases hormones which are basically chemicals that travel via the bloodstream to specific organs in the body to control things like heart rate, glucose release rate, etc. This is how homeostasis in maintained.
Answer:
The correct answer is D
Explanation:
I took the test and it works
