Multiple Choice
Aerobic organisms first started building up oxygen in the Earth's atmosphere around
A) 4.6 billion years ago
B) 3.5 billion years ago
C) 4.0 billion years ago
D) 2.5 billion years ago
Correct Answer:

Verified
Correct Answer:
Verified
Related Questions
Q45: The "bottom-up" approach to creating artificial life
Q46: Why can studies of carbon isotopes be
Q47: Where did the asteroid that is believed
Q48: In 2014, when scientists used a laser
Q49: Life probably did not originate on the
Q51: One theory for the origin of life
Q52: The point in time at which oxygen
Q53: The colonization of land by plants appears
Q54: The most severe mass extinction during the
Q55: Which of the following was an important