What is the series of changes beginning with conception, an organism undergoes until the adult stage is reached?

Depends on the organism. Insects (and many other invertabrates) have four stages, from egg to larvae to pupae to adult. Reptiles and birds go from egg to hatchling to adult. Mammals (for the most part) go from fertilized egg to fetus to newborn to developing youngster to adult. Marsupial mammals have a stage before the newborn stage, the "pouch stage" as it were, when the fetus crawls from the uterus to the pouch where it completes its development as an animal.