The origin of the mitochondrion and chloroplast is hypothesized to have involved
A)the fusion of two archean cells to form an early eukaryote.
B)the absorption of RNA from prokaryotic cells.
C)prokaryotic cells that became internal symbionts within an early eukaryotic cell.
D)the uptake of free DNA from the environment.
E)prokaryotic cells being engulfed and becoming external symbionts within an early bacteria cell.

Question

Quizplus · Accepted Answer

The endosymbiotic theory hypothesizes that mitochondria and chloroplasts were once free-living prokaryotic cells that were engulfed and became internal symbionts within an early eukaryotic cell. This theory is supported by the presence of double membranes, the fact that mitochondria and chloroplasts have their circular DNA, and the similarity of their DNA to that of prokaryotic cells.

The Origin of the Mitochondrion and Chloroplast Is Hypothesized to Have