Question

Many protists such as dinoflagellates, stramenopiles, and euglenids contain plastics that have three or even four membranes, as well as DNA similar to that of cyanobacteria. A hypothesis that explains these characteristics is:
a) transformation
b)congugation.
c) transduction
d) endosymbiosis
e)binary fission.

Answer 1

d) endosymbiosis.

Endosymbiotic theory is the hypothesis behind the formation of membrane-bound cell organelles. It is been believed that cyanobacteria which have the capability of oxidative photosynthesis have been engulfed by the protist and inside the protist body, cyanobacteria started living in a mutualistic relationship, which later has been converted to the cell organell plastid. This is because plastid also contain a genome of its own and can continue oxidative photosynthesis inside the protist body.