medium · LSAT Reading Comprehension

The endosymbiotic theory proposes that key organelles in eukaryotic cells, such as mitochondria and chloroplasts, originated as independent prokaryotic organisms that were engulfed by a larger host cell. Instead of being digested, these smaller cells formed a symbiotic relationship with the host, eventually becoming indispensable components of the cell. Several lines of evidence support this theory. Both mitochondria and chloroplasts contain their own DNA, which is circular and lacks histones, much like the DNA of modern bacteria. Furthermore, these organelles replicate through a process similar to binary fission, independent of the host cell's nuclear division. They also possess double membranes, the inner of which has a chemical composition more similar to bacterial membranes than to the other membranes of the eukaryotic cell.

If a scientist discovered a new organelle in a eukaryotic cell that possessed a single membrane and shared the same DNA structure as the cell's nucleus, how would this discovery most likely relate to the endosymbiotic theory?

Its traits would fail to match the hallmarks the theory uses to identify an organelle of endosymbiotic origin.
It would lend the theory powerful new support as a third organelle descended from an engulfed cell.
The scientist would infer it descends from an ancient bacterium that happened to lack circular DNA.
The scientist would conclude it reproduces by binary fission, as all eukaryotic organelles do.
It would confirm that double membranes are unnecessary for an organelle to have an endosymbiotic past.

If a scientist discovered a new organelle in a eukaryotic cell that possessed a single membrane and shared the same DNA structure as the cell's nucleus, how would this discovery most likely relate to the endosymbiotic theory?

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