The answer is:
- mitochondria and chloroplasts originated as ingested prokaryotes
- mitochondria and chloroplasts have their own DNA
Prokaryotes are exist in simple form organisms (such as single celled animals) Plants in general are considered to be complex organism. Since mitochondria and Chloroplast have separates DNA this fact could be used as an indicator that at one point in time complex organisms were originated from simple form organisms that undergone the process of evolution.
The endosymbiotic theory states that mitochondria and chloroplasts originated as ingested prokaryotes; one piece of evidence supporting this theory is the fact that mitochondria and chloroplasts have their own DNA.
