Brown algae chloroplasts differ from those of cyanobacteria. Fourmembranes surround brown algae chloroplasts while cyanobacteriachloroplasts have double membrane. This quadruple membrane in brownalgae suggests that they evolved via secondary endosymbioisis,perhaps via ingestion of red algae which had already acquired achloroplast from a cyanabacterium through primaryendosysmbiosis.
a) Distinguish primary endosymbiosis from secondaryendosymbiosis.