The two-layered sac surrounding the heart is the pericardium.
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ANSWER: 8.9
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this answer is B. full landfill and another answer is Agricultural runoff (apex)
I belive that the emperor penguin fits all the criteria of Group B.
Answer:
People with the sickle cell mutation in both copies of the HBB gene produce proteins that clump together and lead to changes in the shape and behavior of red blood cells.