1) Which of these is NOT a characteristic of life as we know it?
D. reproduction without mutations.
2) The basic idea about the origin of life on the earth is that:
B. life arose from nonlife in a natural way.
3) Which of these elements does NOT play a role in the chemistry of life as we know it?
B. Helium.
4) Life here centers on carbon chemistry. What is the astronomical source of that carbon?
B. Supernova explosions and strong stellar winds.