The umbilical cord contains one umbilical vein and two arteries. Hope this helps.
Bacteria to amphibians. amphibians started to turn to fish and some started walking to land. They started laying eggs and turning into reptiles. those reptiles started growing hair turning them into four legged mammals. the mammals then turned to primates which evolved into us.
Answer:
the answer is d
Explanation:
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Answer:the decline of lichens is an important indicator of an imbalance in the ecosystem. this research can help system ecologists predict how pollution will affect the entire ecosystem
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