Answer to Question 1ANS: A
The moon orbiting Earth resulted from the initial collision with another planetary body about the size
of Mars. The collision ejected some rocky mantle while the metallic core of that body fell into Earth's
core. The rocky mantle began to condense to form the moon we know today. Information can be found
in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density
Answer to Question 2ANS: B
In laboratory experiments, gases and compounds thought to be similar to Earth's early atmosphere
were exposed to light, heat, and electrical sparks; the result was the production of simple sugars, small
proteins, and nucleotides. The absence of free oxygen seemed to be the key factor. Information can be
found in the section Life Probably Originated in the Ocean.