The evolution of organisms that use oxygen in their respiration was possible only because of the action of a group of bacteria that produced oxygen and changed the Earth's atmosphere from an anoxic one to one rich in oxygen. That group of bacteria was:

A. cyanobacteria
B. spirochaetes
C. proteobacteria
D. Staphylococcus
E. actinobacteria


A. cyanobacteria

Biology & Microbiology

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The ____ phylum consists of vascular, seed-bearing plants, including pines, spruces, firs, hemlocks, junipers,

cypresses, and redwoods. Most of them are evergreens that form woody reproductive cones.

a. Cycadophyta b. Anthophyta c. Gnetophyta d. Coniferophyta e. Ginkgophyta

Biology & Microbiology

Which cellular component's main function is to make lipids, enzymes, and proteins for secretion to the external environment?

a. nucleus b. mitochondria c. endomembrane system d. cytoskeleton e. cell membrane

Biology & Microbiology

Some bones have __________ that makes blood cells. Fill in the blank(s) with the appropriate word(s)

Biology & Microbiology

Which of the following is NOT produced in the

synthesis (light-independent) reactions? a. NADPH b. phosphoglyceric acid (PGA) c. phosphoglyceraldehyde (PGAL) d. glucose e. ribulose bisphosphate

Biology & Microbiology