They're the only vein that carries oygenated blood
Answer:
The layer of Earth's atmosphere where atoms and molecules escape into space is referred to as the exosphere. :)
Answer:
People throw their trash and pollution into the fresh water and make it not as fresh or safe to the animals as much as it could be.
Explanation:
"The earliest evidence of life on Earth comes from fossils discovered in Western Australia that date back to about 3.5 billion years ago. These fossils are of structures known as stromatolites, which are, in many cases, formed by the growth of layer upon layer of single-celled microbes, such as cyanobacteria. (Stromatolites are also made by present-day microbes, not just prehistoric ones.)
The earliest fossils of microbes themselves, rather than just their by-products, preserve the remains of what scientists think are sulfur-metabolizing bacteria. The fossils also come from Australia and date to about 3.4 billion years ago
Bacteria are relatively complex, suggesting that life probably began a good deal earlier than 3.5 billion years ago. However, the lack of earlier fossil evidence makes pinpointing the time of life’s origin difficult (if not impossible)."
(credit: https://www.khanacademy.org/science/biology/history-of-life-on-earth/history-life-on-earth/a/hypotheses-about-the-origins-of-life)
<u>and for the love of god please change that profile picture</u>
