[Campbell Biology P.583] Which of the following statements regarding the endosymbiotic theor... | Practice Question

Which of the following statements regarding the endosymbiotic theory and the evolution of eukaryotic organelles is most accurate based on the provided text?

  • A: The oldest widely accepted eukaryotic fossils are of single-celled organisms that lived approximately 2.7 billion years ago.
  • B: The serial endosymbiosis hypothesis suggests that plastids evolved before mitochondria through a sequence of endosymbiotic events.
  • C: Current evidence indicates that the prokaryotic ancestor of the mitochondrion probably entered the host cell as undigested prey or an internal parasite.
  • D: The host cell in the endosymbiotic event that led to mitochondria was most likely a bacterium.

Explanation

The text states: "The prokaryotic ancestor of the mitochondrion probably entered the host cell as undigested prey or an internal parasite. Though such a process may seem unlikely, scientists have directly observed cases in which endosymbionts that began as prey or parasites developed a mutually beneficial relationship with a host in as little as five years."