Why was important for miller and urey to sterilized the apparatus to kill any bacteria in it?

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands