Which of the following statements support(s)the theory of the endosymbiotic origin of mitochondria and plastids?
I.Mitochondria and plastids have circular DNA and replicate by splitting.
II.Mitochondria and plastids have ribosomes.
III.Mitochondrial and plastid ribosomal RNA sequences are more similar to cytoplasmic ribosomes than to bacterial ones.
IV.The inner membranes of plastids and mitochondria have transport proteins homologous to those in bacterial plasma membranes.
A)I only
B)I and II only
C)III only
D)I,II,and IV

Question

Quizplus · Accepted Answer

All of the statements support the theory of the endosymbiotic origin of mitochondria and plastids. Circular DNA and replication by splitting are characteristics of prokaryotic cells, which supports the idea that mitochondria and plastids were once free-living bacteria that were engulfed by eukaryotic cells. The presence of ribosomes in mitochondria and plastids also suggests a prokaryotic origin, as eukaryotic ribosomes are structurally and functionally different. The similarity of mitochondrial and plastid ribosomal RNA sequences to cytoplasmic ribosomes rather than bacterial ones suggests that they have evolved from eukaryotic cells rather than being acquired through horizontal gene transfer. Finally, the presence of transport proteins homologous to those found in bacterial plasma membranes in the inner membranes of mitochondria and plastids supports the endosymbiotic theory.

Which of the Following Statements Support(s)the Theory of the Endosymbiotic