5. Cell Components

Endosymbiotic theory is supported by the discovery of non-nuclear DNA in the ______ and ________ organelles.

According to the endosymbiotic theory, which of the following is likely the ancestor of the mitochondria?

Plastids that are surrounded by more than two membranes are evidence of

a. Evolution from mitochondria.

b. Fusion of plastids.

c. Origin of the plastids from archaea.

d. Secondary endosymbiosis.

Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because

a. The products of photosynthesis could not be metabolized without mitochondrial enzymes.

b. All eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.

c. Mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA.

d. Without mitochondrial CO₂ production, photosynthesis could not occur.

Consider the endosymbiosis theory for the origin of the mitochondrion. How did each endosymbiotic partner benefit from the relationship?

Why was finding a close relationship between mitochondrial DNA and bacterial DNA considered particularly strong evidence in favor of the endosymbiosis theory?