When did the level of oxygen in Earth's atmosphere become high enough to sustain aerobic respiration?

A) 1.0 billion years ago
B) 1.5 billion years ago
C) 2.7 billion years ago
D) 3.5 billion years ago


Answer: C

Biology & Microbiology

You might also like to view...

How does the Black Queen Hypothesis explain the effect of gene deletions on bacterial evolution?

What will be an ideal response?

Biology & Microbiology

The eukaryotic chromosome is composed of ____

a. DNA only b. RNA only c. DNA and carbohydrate d. DNA and protein e. RNA and protein

Biology & Microbiology

When you collect a sand dollar on the beach, you are looking at the shell of an echinoderm consisting

of ossicles formed from calcium carbonate crystals.

Indicate whether the statement is true or false.

Biology & Microbiology

Hirudinea is the only class of annelids that contains:

A. species that are parasitic blood suckers B. species with a segmented body C. parapodia D. a gizzard E. a clitellum

Biology & Microbiology