Which of the Following Facts Provides Evidence for Endosymbiosis

Question

Which of the following facts provides evidence for endosymbiosis?
A) Mitochondria and chloroplasts have their own DNA, which replicates independently of the nuclear DNA.
B) Ribosomes in mitochondria and chloroplasts have a structure similar to bacterial ribosomes.
C) Chloroplasts have certain gene sequences in their DNA, which indicate a relationship with cyanobacteria.
D) Both "a" and "b" above provide such evidence.
E) All of the above provide such evidence.

Accepted Answer

All of the above provide evidence for endosymbiosis. The fact that mitochondria and chloroplasts have their own DNA (A) and that their ribosomes have a structure similar to bacterial ribosomes (B) suggests that they were once free-living bacteria that were engulfed by a host cell. The presence of certain gene sequences in chloroplast DNA that indicate a relationship with cyanobacteria (C) provides additional evidence for the endosymbiotic theory.