The microscopic roundworm Caenorhabditis elegans is a host for the pathogenic bacterium Serratia marcescens.Researchers genetically manipulated the mating system of C.elegans, producing populations that mated either sexually or asexually (by self-fertilization).When exposed to the S.marcescens parasite, self-fertilizing populations of C.elegans rapidly became extinct.Sexually reproducing populations survived.This suggests that, to maintain healthy populations, C.elegans requires
A) the absence of S. marcescens.
B) the presence of S. marcescens.
C) genetic variation, which allows adaptation to S. marcescens.
D) genetic uniformity, which leads to stable populations.
E) a natural ecosystem where genetic manipulation does not occur.

Question

Quizplus · Accepted Answer

The fact that sexually reproducing populations survived indicates that genetic variation played a role in allowing some individuals to resist and survive the S. marcescens parasite. This suggests that C. elegans requires genetic variation to maintain healthy populations. Therefore, option C is the best choice. The absence or presence of S. marcescens (options A and B) do not entirely explain the survival of sexually reproducing populations. Genetic uniformity (option D) would not have allowed for resistance to the pathogen. The natural ecosystem where genetic manipulation does not occur (option E) is not relevant to the study since the researchers purposely genetically manipulated the C. elegans populations.

The Microscopic Roundworm Caenorhabditis Elegans Is a Host for the Pathogenic