MHT-CET Biology Crash Course “Asexual Reproduction in Animals” Class 12

Asexual Reproduction in Animals” MHT-CET Class 12 Biology Crash Course| ChapterReproduction in Lower & Higher Animals

In this session Jyoti A. Shete will discuss the theory and MCQ’s of “Asexual Reproduction in Animals”. The session will be useful for all the aspirants of MHT-CET 2022. The session will be in Marathi and English.

Asexual Reproduction in Animals“:-

  • Reproduction is one of the major life process of any living organisms.
  • It it help in maintaining the continuity of species.
  • Reproduction is defined as biological process of formation of new life forms from preexisting similar life .
  • It is a vital process which enables species to survive over a long period generation after generation.
  • Even individuals have a limited period of timeI.e. there life span.
  • Reproduction in animals occurs mainly by two methods of Asexual and sexual.

Asexual reproduction in animals

  • When offsprings are produced by a single parent without involvement of gametic fusion reproduction is called
  • As a result offspring that are produced are not only similar to one another but are also exact copies of their parent that a group of morphological and genetically similar individual is called as clone.

Characteristics of Asexual Reproduction

  • Single parent is involved that is uniparental condition.
  • Gametes are not formed.
  • No fertilization .
  • Only mitotic cell division.
  • Daughter organisms are genetically and morphologically identical to parent
  • Multiplicationoccurs rapidly.
  • It is common method among lower animals.

The lower animals reproduce asexually by gemmule formation, budding and fragmentation.

1.Gemmule formation

  • Also called as endogenous or internal budding.
  • Sponges reproduce asexually via. gemmule formation.
  • Gemmule is an internal bud formed only in sponges to overcome unfavorable conditions.
  • The structure of the gemmule includes the micropyle, spicule, inner layer, archaeocytes and outer layer.
  • It possesses an asexually produced mass or aggregation of dormant cells known as archaeocytes.
  • These cells are capable of developing into a new organism
  • The archaeocytes get coated by a thick resistant layer of secretion by amoebocytes.
  • Monaxon spicules are secreted by scleroblasts in between theinner and outer membrane.
  • On return of favorable conditions of water and temperature, the gemmules hatch and develop into a new individual.
  • There is a minute opening called micropyle through which the cells (new individuals) come out during favourable conditions.

2. Budding

  • It is a simple method of a sexual reproduction normally occuring in favourable conditions.
  • It is seen in variety of animals like coelenterates (Hydra and corals) and in some colonial ascidians.
  • In hydra a small outgrowth is produced towards the basal end of the body.
  • It develops as buds which grows and forms tentacles.
  • This buds eventually develops into a new individual.
  • The young Hydra gets detached from parent and become an independent new organism.

3. Fragmentation

  • The parent body breaks into two or more pieces are called as fragments each fragment develop into individual .
  • It is found in sponges, sea anemones and echinoderms in starfish one arm with a part of central disc can develop into a starfish.
  • The parental body of planaria breaks up into two or more fragments.
  • The anterior end exerts a pull on the posterior end resulting in constriction in the middle part and splitting into two pieces each piece grows into a new planaria.
  • That means two clones of original parent are formed.

4. Regenaration

  • Regenaration in Biology refers to the process observed in all living organisms from unicellular bacteria up to most complex multicellular forms eg. humans.
  • Regenarationinvolves asexual processes it differs from reproduction.
  • Asexual reproduction involve the formation of progeny of an individual, regenaration in an organism fundamentally for repair,regrow or restore its lost or damaged part.


Asexual Reproduction MCQs

1.Gemmule formation takes place in

(A) Hydra

(B) Spongilla

(C) Planaria

(D) Amoeba

Ans.(B) Spongilla

2.Hydra multiplies asexually by

(A) budding

(B) gemmule formation

(C) regeneration

(D) both (A) and (B)

Ans.(A) Budding

3.Planaria reproduces asexually through

(A) budding

(B) gemmule formation

(C) fragmentation

(D) amphimixis

Ans.(C) Fragmentation

4______Is a life process that is not essential for an individual’s survival but for survival of species.

(A) growth

(B) Reproduction

(C) Respiration

(D) Nutrition

Ans.(B) Reproduction

5. Regenaration

(A) ascaris

(B) planaria

(C) prawn

(D) Salmonella

Ans.(B) Planaria

Ans.(D)Both A and C

6. Regenaration as a method of sexual reproduction is observed in

(A) ascaris

(B) planaria

(C) prawn

(D) Salmonella

Ans.(B) Planaria

7. Asexual reproductioninvolve

(A) only Meiosis

(B) only mitosis

(C) Both mitosis and meiosis

(D) either mitosis or meiosis

 Ans.(B)Only Mitosis


 

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शिक्षणानुसार जाहिराती

७ वी (7th) दहावी (SSC) बारावी (HSC) डिप्लोमा आय.टी.आय पदवी
पदव्युत्तर शिक्षण बी.एड एम.एड एल.एल.बी / एल.एल.एम बीएससी एमबीए
बीसीए एमसीए बी.कॉम एम.कॉम GNM/ANM एमएससी
बी.फार्म एम.फार्म बी.ई एम.ई BAMS/BHMS एम.बी.बी.एस / एम.डी
बी.टेक एम.टेक MS-CIT