The ecosystem is an ecological system consisting of all of its biotic and abiotic factors
Vertebrates developed about 550 million years ago. The oldest vertebrate fossils are those of FISH with no jaws. These e<span>arly jawless fish did not have paired fins and their bodies were covered with heavy, bony scaled, but their skeletons were made of cartilage. For the next 50 million years, they were the only vertebrates.</span>
Answer:
Leukocytes are a hindrance in a blood transfusion. They can be filtered out and improve a blood transfusion.
Explanation:
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