Which of the following provides support for the endosymbiotic hypothesis?

• A. All prokaryotes have a nucleus.
• B. Mitochondria and chloroplasts contain their own circular DNA similar to bacterial DNA.
• C. Mitochondria and chloroplasts are formed by the Golgi apparatus.
• D. Eukaryotic cells lack internal membrane-bound organelles.

Answer: (B)

Verified step by step guidance

1. Understand the endosymbiotic hypothesis: This theory suggests that mitochondria and chloroplasts in eukaryotic cells originated from free-living prokaryotic cells that were engulfed by ancestral eukaryotic cells. Over time, these prokaryotes formed a symbiotic relationship with the host cell.
2. Evaluate the key evidence supporting the hypothesis: Mitochondria and chloroplasts contain their own circular DNA, which is similar to the DNA found in prokaryotes (bacteria). This is a strong indication of their prokaryotic origin.
3. Compare the structure of mitochondria and chloroplasts to prokaryotes: Both organelles have double membranes, which is consistent with the engulfing process described in the hypothesis. Additionally, they replicate independently of the host cell using a process similar to binary fission, which is characteristic of prokaryotes.
4. Eliminate incorrect options: The statement 'All prokaryotes have a nucleus' is false because prokaryotes lack a nucleus. The statement 'Mitochondria and chloroplasts are formed by the Golgi apparatus' is incorrect because these organelles are not formed by the Golgi apparatus. The statement 'Eukaryotic cells lack internal membrane-bound organelles' is also false because eukaryotic cells are defined by the presence of membrane-bound organelles.
5. Conclude with the correct answer: The statement 'Mitochondria and chloroplasts contain their own circular DNA similar to bacterial DNA' provides strong support for the endosymbiotic hypothesis, as it aligns with the evidence of their prokaryotic origin.