A - Monaxon spicules
B - Micropyle
C - Outer membrane
D - Archaeocytes
E - Inner membrane

(i) Arrhenotoky - e.g. honey bees
(ii) Thelytoky - e.g. Solenobia
(iii) Amphitoky - e.g. Aphis.

In artificial parthenogenesis, the unfertilized egg (ovum) is induced to develop into a complete individual by physical or chemical stimuli. E.g. Annelid and seaurchin eggs.

Juvenile phase I Vegetative phase, reproductive phasel maturity phase, Senescent phase.

It is a type of fertilization in merogamy, the fusion of small sized and morphologically different gametes (merogametes) takes place.

It is a type of fertilization. In exogamy, the male and female gametes are produced by different parents and they fuse to form a zygote. So it is biparental. E.g. Human - dioecious or unisexual animal.

It is a type of regeneration. In morphallaxis the whole body grows from a small fragment. E.g. Hydra. 

(i) Plasmotomy is the division of multinucleated parent into many multinucleate daughter individuals, with the division of nuclei.
(ii) Nuclear division occurs later to maintain normal number of nuclei (e,g:) Opalina and Pelomyxa.
(iii) Plasmotomy occurs in Opalina and Pelomyxa.
(iv) It is a method of asexual reproduction

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

 

In monocellular organs cell division is itself a mode of reproduction. (e.g:) Bacteria, Euglena and Amoeba.

Isogamy. Eg: Monocystis

(a) Arrhenotoky: In this type, only males are produced by parthenogenesis. eg: 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.

Schizogony	Sporogony
In schizogony, the multiple fission occurs in the schizont	In sporogony, the multiple fission occurs in the oocyte.
It results in the formation of merozoites	It results in the formation of sporozoites

(i) In fragmentation, the parent body breaks into fragments (pieces) and each of the fragment has the potential to develop into a new individual.
(ii) Fragmentation or pedal laceration occurs in many genera of sea anemones.
(iii) Lobes are constricted off from the pedal disc and each of the lobe grows mesenteries and tentacles to form a new sea anemone.

(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) In Tape worm the gravid proglottids are regularly cut off either singly or in groups from the posterior end by a process called apolysis.
(ii) This is very significant since it helps in transferring the developed embryos from the primary host (man) to find a secondary host (pig).

(i) In some metazoan animals, a special type of transverse fission called strobilation occurs.
(ii) In the process of strobilation, several transverse fissions occur simultaneously giving rise to a number of individuals which often do not separate immediately from each other. E.g. Aurelia.

(i) In Plasmodium, multiple fission occurs in the schizont and in the oocyte stages. When multiple fission occurs in the schizont, the process is called schizogony and the daughter individuals are called merozoites.
(ii) When multiple fission occurs in the oocyte, it is called sporogony and the daughter individuals are called sporozoites.

1. In unicellular organism there is no special structure for reproduction.
2. In binary fission the entire parent body constitute the reproductive unit and disappears when its division into two daughter unicellular cell is completed.
3. These two daughter cells function as two new individuals.
4. There is no remains of parent body cell and parent cannot be said to have died.
5. In fact after binary fission parent continues living as two daughter individual.
Hence, the unicellular organisms which undergo binary fission are called immortal (no natural death).

1. Sexual reproduction is considered to be a better mode of reproduction because it creates a hybrid that has more vigor than the parents.
2. It also creates the variation in off springs making its survival better.
3. The fact that most of the eukaryotes reproduce sexually in evidence of its evolutionary success.
4. In many animals, it is actually the only mode of reproduction.

(a) Hologamy: In Hologamy, the adult individuals do not produce gametes, but they themselves act as gametes and fuse to form new individuals.
E.g: Trichonympha
(b) Isogamy: Fusion of morphologically & physiologically similar gametes.
E.g: Monocystis
(c) Anisogamy: Fusion of morphologically & physiologically dissimilar gametes.
Eg: Vertebrates.
(d) Merogamy: Fusion of small-sized morphologically different gametes (microgametes)
(e) Paedogamy: Fusion of young individuals produced immediately after the mitotic division of adult parent cell.

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.

In binary fission, the parent organism divides into two halves and each half forms a daughter individual. The nucleus divides first amitotically or mitotically (karyokinesis), followed by the division of the cytoplasm (cytokinesis). The resultant offsprings are genetically identical to the parent. Depending on the plane of fission, binary fission is of the following types
(i) Simple irregular binary fission
(ii) Transverse binary fission
(iii) Longitudinal binary fission
(iv) Oblique binary fission
(i) Simple irregular binary fission is seen in Amoeba like irregular shaped organisms, where the plane of division is hard to observe. The contractile vacuoles cease to function and disappear. The nucleoli disintegrate and the nucleus divides mitotically. The cell then constricts in the middle, so the cytoplasm divides and forms two daughter cells.

(ii) In Transverse binary fission, the plane of the division runs along the transverse axis of the individual. E.g. Paramecium and Planaria. In Paramecium the macronucleus divides by amitosis and the micronucleus divides by mitosis.

(iii) In Longitudinal binary fission the nucleus and the cytoplasm divides in the longitudinal axis of the organism. In flagellates, the flagellum is retained usually by one daughter cell. The basal granule is divided into two and the new basal granule forms a flagellum in the other daughter individual. E.g. Vorticella and Euglena.
(iv) In Oblique binary fission the plane of division is oblique. It is seen in dinoflagellates. E.g. Ceratium.

(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

(a) Some organisms like honeybees are called parthenogenetic animals.
1. In case of honeybees both haploid and diploid individuals formed, as a result of incomplete parthenogenesis.
2. Both sexual reproduction and parthenogenesis are inclusive.
3. Fertilized eggs (zygote) give rise to queen and workers (both are females) by the process of sexual reproduction.
4. Unfertilized eggs (ova) of females develop into drones (males) by the process of parthenogenesis.
(b) A male honeybee has 16 chromosomes where as its female has 32 chromosomes
1. It is because of haplodiploidy which is a sex determination system, in which males develop from unfertilized eggs (parthenogenesis) and are haploid (16n) and females develop frorn fertilized eggs and are diploid (32n) (sexual reproduction).
2. As unfertilized egg carries only half number of chromosome as compared to fertilized egg.
Therefore male honeybees have 16 chromosomes where as female has 32 chromosomes.