The organelle is found in cells of and is theorized to have once been an independent organism.

Photosynthetic autotrophs are organisms that make their own food from sunlight through the work of pigments in chloroplasts. It is thought that chloroplasts in these organisms were once self-sufficient cells.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.