What is important about the habitable zone around a star that makes astronomers believe life could exist there?
a. The level of UV radiation from the star is minimal there.
b. Only in the life zone can complex organic molecules be found.
c. Planets in the life zone will always have oxygen atmospheres.
d. In the life zone water can exist as a liquid.
Question 2
The best places for life to have formed on Earth are believed to have been
a. near the south pole in places where water is frozen solid as ice.
b. on the continent of Africa in the areas with no water.
c. in liquid water, probably in the oceans or pools of water.