Refer to the figure. The phylogenetic tree shows that
A) bacteria lost the mitochondrion and the chloroplast.
B) the eukaryotic mitochondrion was acquired through endosymbiosis from bacteria.
C) bacteria obtained the chloroplast endosymbiotically.
D) the eukaryotic mitochondrion and chloroplast were obtained simultaneously in a single event.
E) the mitochondrion evolved independently three times.

Question

Refer to the figure.  The phylogenetic tree shows that
A) bacteria lost the mitochondrion and the chloroplast. 
B) the eukaryotic mitochondrion was acquired through endosymbiosis from bacteria. 
C) bacteria obtained the chloroplast endosymbiotically. 
D) the eukaryotic mitochondrion and chloroplast were obtained simultaneously in a single event. 
E) the mitochondrion evolved independently three times.

Quizplus · Accepted Answer

The phylogenetic tree shows that eukaryotes and bacteria are separate, but share a common ancestor. Within the eukaryotic lineage, there are two separate branches, one containing organisms with mitochondria and the other containing organisms with chloroplasts. This suggests that the acquisition of mitochondria and chloroplasts occurred independently through endosymbiosis from bacteria. Option A is incorrect because bacteria did not lose the mitochondrion and chloroplast as they do not possess them. Option C is incorrect because there is no evidence of bacterial chloroplast endosymbiosis. Option D is incorrect because the acquisition of mitochondria and chloroplasts occurred independently. Option E is incorrect because the phylogenetic tree shows only two separate branches, one for organisms with mitochondria and one for organisms with chloroplasts.

Refer to the Figure