I think the deficiency of dedicated respiratory and circulatory systems in Planarians does not cause a problem because none of their cells are far removed from the gastrovascular cavity or from the external environment. Planarians are free-living flatworms and form the class Turbellarians in the Phylum Platyhelminthes. Flatworms have three tissue layers, that is the ectoderm, mesoderm, and endoderm.
The chloroplasts had inner membrane
Explanation:
The primitive photoautotrophs utilized hydrogen sulphide as the electron donor to perform photosynthesis for energy production.
Later upon understanding the endosymbiotic relationship of cyanobacteria which resided in the mitochondria of a eukaryotic host cell, the use of chloroplasts for photosynthesis was understood.
Generations after generations led to the development of chloroplasts by the cyanobacteria due to this symbiotic relationships which developed into the chloroplasts.
The unique presence of the inner membrane and its components like the stroma, thyllakoids helped the organism to utilize water as the electron donor for photosynthesis like the present day eukaryotes. This is the main reason why cyanobacteria is considered as the ancestor for eukaryotes.
The organism that has all the adaptations listed above is C. polar bear.
Mr. Turner, my American history teacher, taught us about the U.S. home front during WWII. Enjoy!
