What is Thought to Be the Origin of Mitochondria and Chloroplasts

Question

What is thought to be the origin of mitochondria and chloroplasts?
A) Cyanobacteria for mitochondria, purple bacteria for chloroplasts
B) Purple bacteria for mitochondria, fungi for chloroplasts
C) Purple bacteria for mitochondria, cyanobacteria for chloroplasts
D) Algae for mitochondria, cyanobacteria for chloroplasts

Accepted Answer

The endosymbiotic theory proposes that mitochondria and chloroplasts were once free-living bacteria that were engulfed by another cell and formed a mutualistic relationship, eventually becoming organelles within the cell. The most widely accepted theory suggests that mitochondria were formed from the engulfment of an aerobic purple bacteria, while chloroplasts were formed from the engulfment of a photosynthetic cyanobacteria. Therefore, the correct answer is C, which identifies purple bacteria as the origin of mitochondria and cyanobacteria as the origin of chloroplasts.