Which gas was most likely not present in the Earth's early atmosphere?

a. Methane
b. Hydrogen
c. None of these choices

d. Oxygen
e. Ammonia


d

Biology & Microbiology

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Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

A) binary fission B) mitosis C) random segregation D) gene duplication E) chromosomal condensation

Biology & Microbiology

The allele pool is the sum of all of the alleles in a population

Indicate whether the statement is true or false

Biology & Microbiology

Would a human clone have a bellybutton?

A) Yes B) No

Biology & Microbiology

Organisms that are radially symmetrical have ________ embryonic germ layers

A) two B) three C) four D) five E) six

Biology & Microbiology