[Campbell Biology P.666] Refer to the provided micrograph and its caption. The image shows D... | Practice Question

Refer to the provided micrograph and its caption. The image shows Didinium left engulfing Paramecium right , both ciliates. Based on this information and general biological knowledge, which statement is most accurate regarding ciliates?

  • A: Ciliates belong to the Archaeplastida supergroup and are characterized by photosynthetic activity.
  • B: Ciliates belong to the Unikonta supergroup, and their evolutionary history primarily involves gaining mitochondria from archaea.
  • C: Ciliates belong to the SAR supergroup, which has a complex evolutionary history involving secondary endosymbiosis of red algae.
  • D: Ciliates are more closely related to plants than to other protists, reflecting their shared primary endosymbiotic origin of plastids.

Explanation

Ciliates are part of the SAR Stramenopiles, Alveolates, Rhizarians supergroup. The Alveolates, which include ciliates, dinoflagellates, and apicomplexans, are thought to have originated from a common ancestor that acquired plastids through secondary endosymbiosis from a red alga, although ciliates themselves typically lack plastids and are heterotrophic. This complex evolutionary history places them distantly from Archaeplastida plants, red and green algae and Unikonta amoebozoans, fungi, animals . Therefore, statement C accurately reflects their supergroup and the complex endosymbiotic events in the lineage of Alveolates.