Question

what key feature indicates that mitochondria and chloroplasts were once independent cells? they have their own dna. they are identical dna to host cells. they both lack a membrane.

Explanation:

To determine the key feature indicating mitochondria and chloroplasts were once independent cells, we analyze each option:

• Option 1: Mitochondria and chloroplasts have their own DNA, which supports the endosymbiotic theory (they were once free - living prokaryotes with their own genetic material).
• Option 2: Their DNA is not identical to the host cell's DNA. If they were once independent, their DNA should differ from the host's, so this is incorrect.
• Option 3: Both mitochondria and chloroplasts have membranes (double - membrane structure in mitochondria, double - membrane in chloroplasts too), so this is incorrect.

Answer:

A. They have their own DNA