AP BIOLOGY

Detailed explanation-1: -According to the widely accepted endosymbiotic theory [1] they originated from an ancient cyanobacterium, which was engulfed by a eukaryotic host cell. The metamorphosis of the autonomous cyanobacterium into a cell organelle included the transfer of the cyanobacterial genes to the host nucleus.

Detailed explanation-2: -1: Chloroplasts in plants: A eukaryote with mitochondria engulfed a cyanobacterium in an event of serial primary endosymbiosis, creating a lineage of cells with both organelles. These cyanobacteria have become chloroplasts in modern plant cells.

Detailed explanation-3: -At some point, a eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryote, gradually developing into a mitochondrion.

Detailed explanation-4: -Answer and Explanation: The endosymbiosis theory is an evolutionary theory that describes how eukaryotic cells, plant and animal cells, were formed. It describes how certain organelles such as mitochondria and chloroplast were once free-living single-celled organisms that were taken inside other organisms.

Detailed explanation-5: -Eukaryotic cells may have evolved when multiple cells joined together into one. They began to live in what we call symbiotic relationships. The theory that explains how this could have happened is called endosymbiotic theory. An endosymbiont is one organism that lives inside of another one.