The two semilunar valves, the pulmonary and aortic valves, are closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left.
Answer:
from 60 to 100 beats per minute
The answer would be D, evolved from a common ancestor
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There would be half the number of chromosomes in the gametes...so 4.
Because it is often found in eastern united states
