Regeneration is regrowth in the injured region. Regeneration was first studied in Hydra by Abraham Trembley in 1740. Regeneration is of two types, morphallaxis, and epimorphosis. In morphallaxis, the whole body grows from a small fragment e.g. Hydra and Planaria. When Hydra is accidentally cut into several pieces, each piece can regenerate the lost parts and develop into a whole new individual. The parts usually retain their original polarity, with oral ends, by developing tentacles .and aboral ends, by producing basal discs. Epimorphosis is the replacement of lost body parts. It is of two types, namely reparative and restorative regeneration. In reparative regeneration, only certain damaged tissue can be regenerated, whereas in restorative regeneration severed body parts can develop. e.g. starfish, the tail of wall lizard.

(i) Development of an egg into a complete individual without fertilization is known as parthenogenesis.
(ii) It was first discovered by Charles Bonnet in 1745. Parthenogenesis is of two main types namely, natural Parthenogenesis and artificial Parthenogenesis.
(iii) In certain animals, parthenogenesis occurs regularly, constantly and naturally in their life cycle and is known as natural parthenogenesis.
Natural parthenogenesis are of different types:
a) Arrhenotoky: In this type only males are produced by parthenogenesis. E.g: honey bees
b) Thelytoky: In this type of parthenogenesis only females are produced by parthenogenesis E.g. Solenobia
c) Amphitoky: In this type parthenogenetic egg may develop into individuals of any sex. E.g: Aphis.
(iv) Natural parthenogenesis may be of two types, viz., complete and incomplete. Complete parthenogenesis is the only form of reproduction in certain animals and there is no biparental sexual reproduction. These are no male organisms and so, such individuals are represented by females only.
(v) Incomplete parthenogenesis is found in some animals in which both sexual reproduction and parthenogenesis occurs.
E.g. In honeybees; fertilized eggs (zygotes) develop into queen and workers, whereas unfertilized eggs develop into drones (male).
(vi) In paedogenetic parthenogenesis (paedogenesis) the larvae produce a new generation of larvae by parthenogenesis.
(vii) It occurs in the sporocysts and Redia larvae of liver fluke. It is also seen in the larvae of some insects. E.g. Gall fly.
(viii) In artifical parthenogenesis, the unfertilized egg (ovum) is induced to develop into a complete individual by physical or chemical stimuli. E.g. Annelid and seaurchin eggs.

(a) 

Binary Fission in Amoeba	Multiple fission in Plasmodium
lt results in the production of two individuals from a single parent.	It results in the production of several individuals
lt occurs under favourable conditions	It occurs both under favourable and unfavourable conditions
Nucleus of the parent cell divides only once to form two daughter nuclei	Nucleus of the parent cell undergoes repeated divisions to form a number of daughter nuclei
Cytoplasm divides after nuclear division	Cytoplasm does not divide after each nuclear division but divides during favourable condition
No part of parent body is left unused (e,g: Amoeba)	A part of the body (covering and residuai cytoplasm) is left unused. (e,g: Paramecium)

(b) Budding in yeast and budding in hydra

Budding in Yeast	Budding in Hydra
During budding the cell wall of the parent cell bulges out in the form of an out growth as bud	During budding the ectoderm cells increase and form a small elevation on the body surface as bud.
The parent nucleus divides into two daughter nuclei one of which migrates into bud.	Ectoderm and endoderm are pushed out to form the bud. The bud contains an interior lumen in continuation with parent's gastro vascular cavity (coelenteron)
As the bud enlarges and is fully formed, it is separated from the parentcell and grows into mature yeast. Sometimes a bud may produce another bud over it which is still attached to parent cell forming a false mycelium (or) pseudomycelium	The bud enlarges, develops a mouth and a circle of tentacles at its free end. When fully grown, the bud constricts at the base and finally separates from the parent body and leads an independent life

(c) Regeneration is regrowth in the injured region

Regeneration in Lizard	Regeneration in Planaria
This type of regeneration comes under epimorphosis type.	This type of regeneration comes under morphallaxis type
Several body parts can develop.	When the body is cut into several pieces, each piece can regenerate the lost parts and develops into a whole individual

syngamy	fertilization
It is the fusion of two haploid gametes to form a diploid zygote	It is the act (or) process of rendering fertile zygote as the result of Fertilization

 

juvenile phase	reproductive phase
lt is also known as young and Vegetative Phase	It is also known as Maturity adult Phase
lt is the period of growth between the birth of the individual upto reproductive maturitiy.	The organisms reproduce and their offsprings reach maturity period