The earliest signs of life appeared on Earth during the ____ era

a. Archean
b. Paleozoic
c. Mesozoic
d. Cambrian
e. Cenozoic


ANSWER: a

Biology & Microbiology

You might also like to view...

Members of the Archaea typically thrive in conditions of excessive

A. heat. B. acidity. C. alkalinity. D. salinity. E. All of the choices are correct.

Biology & Microbiology

As an adult, which typical chordate embryonic traits do adult tunicates retain?

a. hollow, dorsal nerve cord b. notochord c. gill slits d. tail extending beyond anus e. carbohydrate “tunic”

Biology & Microbiology

Microbes of the same species that live together and cooperate in some way are 

A. mutualistic. B. colonial. C. commensal. D. opportunistic.

Biology & Microbiology

In cases of __________ growth, a population's growth rate remains constant and greater than zero.

Fill in the blank(s) with the appropriate word(s).

Biology & Microbiology