Answer :
According to endosymbiotic theory, the chloroplast evolved as a result of engulfment and assimilation of a Cyanobacteria by an eukaryotic cell.
Explanation:
- Endosymbiotic theory supports the view that ceratain organelles of the eukaryotic cell evolved as a result of engulfment of single celled organism.
- Evidences that support this theory is the presence of organellar DNA.
- It is assumed that Mitochondria evolved as a result of engulfment and assimilation of an aerobic prokaryote while Chloroplast evolved due to engulfment and assimilation of a photosythetic prokaryote by an Eukaryote.
- After the engulfment ,these organisms however escaped the phagocytosis and began to benefit the eukaryotic Host.
- Soon it lost many of its Genes to the eukaryotic nucleus and became dependent on the Host.
- Thus a symbiotic association was established between the prokaryote and the host.Giving rise to cell organelles.