5. Cell Components

Chloroplasts and mitochondria are thought to be of prokaryotic origin. One piece of evidence that supports this hypothesis is that these organelles contain prokaryotic-like ribosomes. These ribosomes are probably most similar to ribosomes found __________.

Which of the following organelles might be found inside other organelles?

Which of the following statements about chloroplasts and mitochondria is true?

Plastids that are surrounded by more than two membranes are evidence ofa. 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 becausea. 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?

How might the phrase 'ingested but not digested' be used in a description of the endosymbiotic theory?