5.A. is trapped in tree resin, which hardens around it.
B. leaves an impression in sediment that fills with minerals.
C. has hard structures that are surrounded by minerals.
D. becomes encased whole in a material that preserves it.
6.Fossils that are useful for dating, because they are common, easy to identify, widespread, and existed for a brief time are called
A. trace fossils.
B. extinct fossils.
C. index fossils.
D. key fossils.
7. Earth's history is organized by
A. the Precambrian time scale.
B. units representing one million years.
C. the geologic time scale.
D. which plants lived on Earth.
8. Which of the following contributed most to the intense heat of the Hadean eon?
A. Clouds of carbon dioxide, hydrogen, and other gases
B. Frequent collisions with asteroids and meteorites
C. Lightning strikes and volcanic eruptions
D. Closer proximity to the sun than is now the case
9. In the lipid membrane hypothesis, it is proposed that liposomes
A. formed in chimney-like structures at ocean hydrothermal vents.
B. were the result of lightning striking early Earth.
C. acted as barriers between organic molecules and the environment.
D. served as the genetic material on early Earth.
10. Which of the following hypotheses proposes that early organic molecules formed near ocean hydrothermal vents?
A. Iron-sulfide bubbles hypothesis
B. Lipid membrane hypothesis
C. RNA world hypothesis
D. Meteorite hypothesis
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