Question

give an account of reproduction in protozoa
​

Answer 1

Answer:

hiii I am RuchikaJagtap maybe it helps you

Explanation:

Amoebas and flagellates reproduce via asexual reproduction. The most common form of asexual reproduction used by protozoa is binary fission. In binary fission, the organism duplicates its cell parts and then divides itself into two separate organisms.

Answer 2

Answer:

Asexual Reproduction in Protozoa:

The mode of reproduction in which there is no union of gametes. In such a case, only one animal can produce new individuals. Protozoa usually reproduces asexually by binary fission and multiple fission.

I. Binary Fission:

The animal divides and two individuals are produced from one:

1. The micronucleus divides into two by a simplified form of mitosis.

2. The macronucleus divides into two by amitosis.

3. The cytoplasm divides into two equal halves by a constriction.

4. The daughter individuals can recon­struct the wanting structures which it does not obtain from the parent. Asymmetrical structures like gullet, peristome of Paramoecim cannot be equally shared by both the daugh­ter individuals.

Binary fission is again of three types:

a. Transverse fission. The animal divides transversely into two. Examples: Amoeba, Paramoecium, etc.

b. Longitudinal fission. The animal splits into two along the long axis of the body. Examples: Euglena, Vorticella, etc.

c. Oblique binary fission. The plane of fission is oblique. Examples: Dinoflagellata, Ceratium, Cochliodinium,. etc.

II. Multiple Fission or Sporulation:

Many individuals are produced from one at a time. Examples: Some Amoebae, Euglena, Polystomella, etc.

1. The animal becomes encysted, the nucleus divides repeatedly and a large num­ber of minute daughter nuclei are produced.

2. The cytoplasm fragments and a small bit of it surrounds each daughter nucleus and, thus, many minute animals are formed.

3. Under favourable circumstances the cyst bursts and these small animals come out and grow to the adult stage.

Multiple fission is common in sarcomastigophorans and apicomplexans. The process has been differently named according to the period and time of occurrence.

Following types of multiple fission are found in proto­zoa:

a. Gamogony:

Products are gametes. Examples: Monocytes.

b. Scizogony or agamogony occurs in asexual stages:

The resulting individuals are known as agametes or merozoites. Example: Plasmodium.

c. Sporogony:

It occurs following sexual fusion. The products are surrounded by a cyst or a resistant covering and termed as spores. Motile spores are known as swarmer’s or swarmospores.

The swarmers are of two types:

i. Flagellospore. Spores bearing flagella.

ii. Pseudopodiospore or amoebospore. Spores beaning pseudopodia.

III. Plasmotomy:

The multinucleate individual divides into many small multinucleate offspring’s by simple division of cytoplasm independent of nuclear division. The daughter individuals regain the normal size and the number of nuclei is restored by further nuclear division.

IV. Budding:

New individuals are produced by separa­tion of a portion of the cytoplasm of the parent organism with a daughter nucleus. It may be simple or multiple, exogenous or endogenous. Budding is common in suctorians. Examples: Noctiluca, Tokophrya, etc.