3. PROTOZOA:-
Protozoa is small,microscopic; single-celled or unicellular organisms.
Free living protozoa mostly aquatic, fresh and marine water.
Parasitic protozoa live inside the bodies of animals and plants.
It is having one or more nuclie,but no nucleus ever in charge of specialized
part of cytoplasm.
They exist either single or in colonies.
4. REPRODUCTION:-
Protozoa carried out their reproduction by asexual and sexual mode of
reproduction.
The higher group of protozoa follow mainly sexual reproduction.
Some protozoa carried out both asexual and sexual reproduction based on the
types of the host cells.
5. SEXUAL REPRODUCTION:-
Sexual reproduction means the liberation of special reproductive cells from
the body; and the fertilization of ovum by spermatozoon.
As the protozoa do not have the so called ‘body,’ they cannot be said to
exhibit sexual reproduction in this sense.
Certain protozoa perform sexual reproduction is of regular occurrence.
For example,Plasmodium in mosquito cannot be completed without
gametogenesis and syngamy.
Gametogenesis is termed as gametic meiosis.
8. 1) Syngamy :-
Syngamy is the complete and permanent fusion of the union of two gametes
for the generation of zygote.
The nuclei of the gametes fuse to form a zygote nucleus or synkaryon.
The zygote develops into the adult directly or fission of various types in
different forms.
Syngamy may be of many types depending upon the degree of differentiation
displayed bye the fusing gametes.
(a) Autogamy.
(b) Exogamy.
(c) paedogamy.
(d) Hologamy.
(e) Isogamy.
(f) Anisogamy.
(g) macrogamy.
9. Autogamy :- The production of gametes by the division of single parent cells.
Exogamy :- Syngamy taking places between the offspring of different
parents.
Paedogamy :- Fusing individuals are young.
Hologamy :- Fusion of two mature individuals of normal size behaving
themselves as gametes.
Merogamy :- The uniting individual called merogametes or gametes and are
formed by special fission.
10. Isogamy :- Fusion of two gametes having similar shape and size is called
isogametes and they union called isogamy.
Anisogamy :- Fusion of teo gametes having differ in size, shape and
behaviour, they termed as anisogametes or heterogametes. Their fusion is
known asanisogamy and heterogamy.
Macrogamy:- It is a syngamy between macrogametes of the species.
Macrogametes means small gametes (male gametes in protozoa)
Microgametes means large gametes (female gametes in protozoa)
11. CONJUGATION:-
Random contact brings individuals of opposite mating types together (called
conjugation)
Meiosis results in four haploid pronuclei
Three pronuclei and the macronucleus degenerate.Mitosis and mutual
exchange of pronuclei is followed by fusion of the pronuclei.
Conjugants separate.Nuclear divisions that restore nuclear characteristics of
species follow.Cytoplasmic divisions may accompany these events.
