The Ancestral Organism That Gave Rise to the Modern-Day Chloroplast

Question

The ancestral organism that gave rise to the modern-day chloroplast was
A) rickettsia.
B) a cyanobacterium.
C) Wolbachia.
D) a rhizobial bacteroid.
E) a methanogen.

Accepted Answer

The modern-day chloroplasts are thought to have evolved from an endosymbiotic relationship between a photosynthetic cyanobacterium and a eukaryotic cell. This is supported by genetic and structural similarities between cyanobacteria and chloroplasts, as well as the fact that chloroplasts have their own circular DNA, similar to bacteria.