Which statement does not support the endosymbiotic theory?
A Mitochondria and chloroplasts reproduce independently from the cell.
B Mitochondria and chloroplasts contain their own ribosomes.
C Mitochondria and chloroplasts have DNA that resembles bacterial DNA.
DMitochondria and chloroplasts are much larger than prokaryotic cells.
The Correct Answer and Explanation is :
The correct answer is D: Mitochondria and chloroplasts are much larger than prokaryotic cells.
The endosymbiotic theory explains how eukaryotic cells, which are more complex, evolved from simpler prokaryotic cells through a symbiotic relationship. According to this theory, certain organelles, such as mitochondria and chloroplasts, were once free-living bacteria (prokaryotic organisms) that were engulfed by a host cell. Over time, these bacteria formed a mutually beneficial relationship with the host, leading to their integration as organelles within the cell.
Explanation of the Other Statements:
- A. Mitochondria and chloroplasts reproduce independently from the cell: This supports the endosymbiotic theory because mitochondria and chloroplasts divide through a process similar to binary fission, which is how prokaryotes reproduce. This independent replication suggests their bacterial origin.
- B. Mitochondria and chloroplasts contain their own ribosomes: This is also consistent with the endosymbiotic theory. The ribosomes found in mitochondria and chloroplasts are more similar to those of bacteria (prokaryotic cells) than to those found in the rest of the eukaryotic cell, reinforcing the idea that these organelles were once independent bacteria.
- C. Mitochondria and chloroplasts have DNA that resembles bacterial DNA: This is another piece of evidence supporting the theory. The DNA in mitochondria and chloroplasts is circular, like bacterial DNA, and distinct from the linear DNA in the nucleus of eukaryotic cells. This resemblance strengthens the argument for their prokaryotic ancestry.
Why Statement D Does Not Support the Theory:
- D. Mitochondria and chloroplasts are much larger than prokaryotic cells: This statement is incorrect and does not support the theory. In fact, mitochondria and chloroplasts are generally smaller than most prokaryotic cells, not larger. If they were larger, it would contradict the idea that these organelles originated as prokaryotic cells, which are typically smaller and less complex than eukaryotic cells. Therefore, this statement is not aligned with the endosymbiotic theory.