one piece of evidence for the endosymbiotic theory comes from examination of membranes surrounding the chloroplasts of microbial eukaryotes that have a history of secondary and/or tertiary endosymbiosis. How might we expect the membranes in these cases to be different?

Endosymbiotic theory states that organelles like mitochondria and chloroplast evolved in eukaryotic cell through the process of symbiosis of individual single cell prokaryotes. In case of secondary endosymbiosis a living cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis. In case of primary endosymbiosis now there is a double phospholipid bilayer. The outermost membrane is derived from the eukaryote and the innermost membrane is it's original phospholipid bilayer. Similarly secondary and tertiary endosymbionts have three membrane and four membranes. E. g. In some dinoflagellates secondary plastids are surrounded by three membranes.