How does the respiratory system in birds differ from the mammalian respiratory system?

the fossil record provides evidence of a common ancestor to many species.

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation:

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.