_____ was probably not present in the Earth's early atmosphere. 

A. H2O
B. NH3
C. O2
D. CO2


C. O2

Biology & Microbiology

You might also like to view...

One of your friends is an excellent pianist. Which statement could be used to describe your friend?

a. Her limbic system is very well developed. b. Her right hemisphere is well developed for musical ability. c. Her left hemisphere is well developed for musical ability. d. Her reticular formation is well developed for musical ability. e. Her right hemisphere is well developed for control over the right side of the body.

Biology & Microbiology

Cytoplasmic DNA is a feature of _______________cells

a. eukaryotic b. prokaryotic c. animal d. plant

Biology & Microbiology

Vlad, 28 years old, is a slender, jumpy man with eyes that seem to bulge out of their sockets. His heart rate is unusually fast. Which of the following conditions does Vlad most likely have?

A) Addison's disease B) acromegaly C) Cushing's syndrome D) Graves' disease

Biology & Microbiology

T or F: When the joint angle between two segments increases, the action that occurs is flexion

What will be an ideal response?

Biology & Microbiology