Organisms have three phases in its life cycle.
(i) Juvenile phase/ vegetative phase is the period of growth between the birth of the individual upto reproductive maturity.
(ii) Reproductive phase/maturity phase the organisms reproduce and their offsprings reach maturity period.
(iii) Senescent phase begins at the end of reproductive phase when degeneration sets in the structure and functioning of the body.

(i)  In Ovoviviparous animals, the embryo develops inside the egg and remains in the mother's body until they are ready to hatch.
(ii) This method of reproduction is similar to Viviparity but the embryos have no placental connection with the mother and receive their nourishment from the egg yolk. Ovoviviparity is seen in fishes like shark.

(i) During unfavorable conditions Amoeba withdraws its pseudopodia and secretes a three-layered, protective, chitinous cyst wall around it and becomes inactive. This phenomenon is called encystment.
(ii) When conditions become favourable, the encysted Amoeba divides by multiple fission and produces many minute amoebae called pseudopodiospore or amoebulae.
(iii) The cyst wall breaks off liberating the young pseudopodiospores.

If multiple fission produces four or many daughter individuals by equal cell division and the young ones do not separate until the process is complete, then this division is called repeated fission. E.g. Vorticella.