Question

A scientist claims that the presence of aquaporins in mitochondrial membranes supports the endosymbiotic theory. Which of the following statements would be evidence that supports the endosymbiotic theory?

A) Aquaporins are present in mitochondria but are considered a vestigial structure that is no longer needed by mitochondria in a eukaryotic cell.
B) Aquaporins were not present in the plasma membrane of ancestral free-living prokaryotic cells evolved to be part of mitochondria in eukaryotic cells due to the need to move water into mitochondria.
C) Aquaporins were present in the mitochondria of ancestral free-living prokaryotic cells.
D) Aquaporins were present in the plasma membrane of ancestral free-living prokaryotic cells.

Answer 1

Evidence supporting the endosymbiotic theory in the context of aquaporins would be that these proteins were present in the plasma membrane of ancestral free-living prokaryotic cells.

Step-by-step explanation:

The presence of aquaporins in mitochondrial membranes that supports the endosymbiotic theory would be evidenced by the fact that aquaporins were already a part of the ancestral free-living prokaryotic cells that evolved into mitochondria within eukaryotic cells. The correct statement that provides evidence for this is: Aquaporins were present in the plasma membrane of ancestral free-living prokaryotic cells.

This supports the endosymbiotic theory, which suggests that a eukaryotic cell engulfed a prokaryotic cell and a mutualistic relationship evolved, leading to the prokaryotic cell becoming an organelle within the eukaryotic host. If aquaporins, which facilitate water transport across cell membranes, were in the membranes of these free-living prokaryotes that later evolved into mitochondria, it would align with the concept of the inner mitochondrial membrane having originated from the engulfed prokaryotic cell.