Question

In which geological era did microbes originated
a) Precambrian
b) Proterozoic
c) Azoic
d) Palaeozoic

Answer 1

Hint: Bacteria existed on Earth from very early in the history of life. The first autotrophic bacteria appeared approximately 2.5 billion years ago. The fossils of the first oxygen dependent animals are found in the Proterozoic era.

Complete answer:
The microbes were the first oxygen dependent organisms (resembles cyanobacteria). After the origin of mycobacteria life began to evolve into more complex organisms.

> Option A, is the Precambrian era, which means before the Cambrian period. In this era hard shelled creatures appeared.

> Option B, is the Proterozoic era. In this era first oxygen dependent organisms are raised. The fossils of bacteria and blue-green algae are found from the Proterozoic era. So, we can day microbes originated in the Proterozoic era.

> Option C, is the azoic era. Age of rocks are found in this era which was present before the appearance of life.

> Option D, is the Palaeozoic era. In this era first vertebrates arose. During the Precambrian era, the azoic era and the Palaeozoic era microbes were not dominant.

Hence, The correct answer is option (B).

Note: Proterozoic is a Greek, the term proterozoic made up of proteros (meaning first) and zoon (meaning life). So, we can say the first life appeared in the Proterozoic era. About one billion years ago the only organisms on earth were cyanobacteria and protozoans, therefore, it was named 'proterozoic'. Proterozoic era is also known as the age of prokaryotic microbes.