Question

in 1967, lynn margulis challenged evolutionary orthodoxy with her paper on the origin of mitosing cells. she argued that eukaryotic cells originated not through gradual accumulation of mutations, but via serial endosymbiosis theory (set)—the symbiotic merger of distinct prokaryotic lineages. although initially dismissed as heresy, margulis’s framework ultimately reoriented the field, suggesting that cooperative integration, rather than competitive struggle, is the primary driver of cellular complexity.
5
which choice best states the main purpose of the text?
a to describe a theoretical proposal and explain how it validated the discipline’s established view of biological complexity.
b to recount how a once - dismissed hypothesis reshaped scientific understanding of how complex cells evolved.
c to detail the specific experimental data that led a researcher to formulate the serial endosymbiosis theory.
d to compare the evolutionary advantages of competitive struggle with those of cooperative integration in prokaryotic lineages.

Explanation:

• Option A: The text does not say the theory "validated" the established view; it reoriented it, so A is incorrect.
• Option B: The text talks about Margulis's once - dismissed hypothesis (SET) and how it reshaped the understanding of complex cell evolution, which matches this option.
• Option C: The text does not detail experimental data leading to SET formulation, so C is wrong.
• Option D: The text is not about comparing the advantages of competitive struggle and cooperative integration; it focuses on the theory's impact, so D is incorrect.

Answer:

B. To recount how a once - dismissed hypothesis reshaped scientific understanding of how complex cells evolved.