Which of the following pieces of evidence supports the claim that mitochondria trace their history back to free-living bacteria? a) mitochondria have their own dna molecules, separate from the rest of the cell's dna b) some protists do not contain mitochondria c) the citric acid cycle occurs in the matrix of mitochondria d) mitochondria converts adp into atp.

The answer is (A) Mitochondria have their own DNA molecules, separate from the rest of the cell's DNA.

The endosymbiotic hypothesis concerns with the presence of two special organelles, mitochondria and chloroplast within the eukaryotic cell. These two organelles have their own set of DNA that is different from the nuclear DNA of the eukaryotic cell. It is believed that a primordial eukaryotic cell was in a symbiotic relationship with mitochondria-like bacterium. The primordial cell eventually engulfed the mitochondria-like bacterium for ATP production to power itself.