Recent Estimates of the Number of Microbes on the Planet

Multiple Choice

Recent estimates of the number of microbes on the planet have expanded almost exponentially, but the number of microorganisms isolated in the lab has not increased at the same rate. How can microbiologists justify the higher estimates if they cannot isolate and grow the microbes in the lab?

A) The huge numbers of diseases without apparent causative agents indicate there are large numbers of unidentified pathogens.
B) Detection of novel enzymes indicates the existence of unidentified microbes.
C) Previous estimates of the abundance of microbes cannot account for the detectable biomass in most environments.
D) New technologies make it possible to detect the nucleic acid sequences of previously unknown organisms.
E) Much more powerful microscopes have made it possible to observe and identify huge numbers of microbes that cannot be isolated.