Researchers have used several pieces of evidence to support the theory of endosymbiosis.Which characteristic of mitochondria and/or chloroplasts present in modern cells is one of these pieces of evidence?
A) When taken out of cells, individual mitochondria and chloroplasts cannot survive on their own.
B) Both mitochondria and chloroplasts function in energy metabolism in the cell.
C) Chloroplasts are found only in plant cells and algae, while mitochondria are found in all eukaryotes.
D) Both mitochondria and chloroplasts have their own DNA that encodes some of the proteins used by the organelles to carry out their biological functions.
E) Many proteins used in the internal spaces of mitochondria and chloroplasts are synthesized in the cell cytosol and then transported across the organelle membranes.

Question

Quizplus · Accepted Answer

The fact that both mitochondria and chloroplasts have their own DNA that encodes some of the proteins they use to carry out their biological functions is a piece of evidence that supports the theory of endosymbiosis. This suggests that they were once free-living prokaryotes that were engulfed by a larger, host cell and evolved into the eukaryotic organelles we see today.

Researchers Have Used Several Pieces of Evidence to Support the Theory