Amarchand Singhvi International School 10...Amarchand Singhvi International School Subject : BiologyClass : XChapter : How do Organisms Reproduce?(Part-1)Topic : Asexual ReproductionTeacher

Amarchand SinghviInternational School

Subject : Biology

Class : X

Chapter : How do Organisms Reproduce?(Part-1)

Topic : Asexual Reproduction

Teacher : Ms. Shweta Trivedi

E-Learning Programme

AMARCHAND SINGHVI INTERNATIONAL SCHOOL

REPRODUCTION.• It is a biological process by which an organism reproduces an offspring who

is biologically similar to the organism. • Reproduction enables and ensures the continuity of species, generation

after generation. It is the main feature of life on earth. • In absence of reproduction all the animal species would get extinct.


WHY DO ORGANISMS CREATE CARBON COPIES OF THEMSELVES?

• DNA molecule in the nucleus is responsible for the transfer of characters from parents to offsprings.

• During reproduction the two copies of DNA are produced which separate into two cells.

• Every time a DNA is copied there will be a slight variation. So the new individuals may be or may not be exacltly identical to the parents.


VARIATION• Difference between organisms due to change in the DNA sequence is called

as variation.

Importance of variation.• DNA copying is important in organisms to maintain the body design of

different organisms to survive in the existing environment. • But the environment is constantly changing.• If organisms cannot adjust to the change then their species would get

extinct.• If there are some variations in the individuals then they may be able to

survive in the environment and continue the species.



ASEXUAL REPRODUCTION.• Asexual reproduction is a type of reproduction which does not involve the

fusion of gametes or change in the number of chromosomes. • The offspring that arise by asexual reproduction from a single cell or from

a multicellular organism is exact copy of the parent.


Fission

Binary Multiple


Binary Fission• Binary fission, asexual reproduction by a separation of the body into two new bodies.• In the process of binary fission, an organism duplicates its genetic material, or

deoxyribonucleic acid (DNA), and then divides into two parts along with cytoplasmdivision with each new organism receiving one copy of DNA.

• Daughter cells are exactly like parents.

• It is an Asexual mode of reproduction in organisms. The nucleus of organism dividesrepeatedly to form a number of equal sized daughter nuclei and each daughter nucleibreaks away together a small portion of the cytoplasm.

• It takes place during unfavourable conditions and a hard covering called cyst is formedoutside the cell.

Multiple Fission


Budding• Budding is a mode of asexual reproduction seen in Hydra and Yeast.• In Hydra, a bud begins to form on the tubular body. The bud then develops a mouth and

tentacles and detaches from its parent. The new Hydra is fully developed and will find asubstrate for its attachment.

• During favorable conditions, yeast reproduces by budding in which a small outgrowth calledbud forms on parent cell.

• After this nucleus of parent cell divides and migrates into bud. This bud increases in size andfinally breaks off.


Fragmentation• Fragmentation is a type of asexual reproduction in which an organism simply breaks in

individual pieces at maturity. • These individual small pieces then grow to form a new organism e.g., Spirogyra. Spirogyra

undergoes fragmentation which results in many filaments. Each filament grows into mature filament.


Regeneration

• Regeneration is the ability of anorganism to grow into a completeindividual when its body is dividedinto many pieces accidently.

• It is carried out by specialized cellswhich proliferate further and makelarge number of cells.

• From this mass of cells different cellsundergo changes to form a completeindividual.


Sporulation

• In sporulation during unfavourablecondition sporangium is formed onthe hyphae which contains asexualreproductive bodies called spores.

• When the sporangia burst , sporescome in contact with moist surfaceand grow into new individual.

• Spores are covered with hard coatwhich protects them from harshweather.


Vegetative propagation• Vegetative propagation is a mode of asexual reproduction.• The vegetative parts of the plants like roots, stem and leaf give rise to a new individual.• The detached part of the plant has cells enough to divide and produce a new individual.

By Stem in Potato By Leaf in Bryophyllum By Root in Sweet Potato


Grafting and layering

Grafting


Advantages of vegetative propagation•Quicker and more certain.•Produces identical quality as the parent.•Plants that do not have viable seed, can be reproduced.•Flowers produced are of superior quality.•Desirable character of fruit can be maintained.


Note: This presentation is a part of the E-Learning Program of Amarchand

Singhvi International School and is created only for educational purpose.

Compilation & presentation : Ms. Shweta Trivedi

Web support & management : Mr. Deepak Chellani

Technical support : Mr. Shivam Gundecha

E-learning Program Co-ordination:

Mr. Prashant Chaturvedi

Produced by

Mr. Mridul Varma (Principal)

Amarchand Singhvi International School

Parekh Parisar, Ward 7A, Gandhidham – Kutch

Gujarat 370201 India

Documents

Amarchand Singhvi International School 10...Amarchand Singhvi International School Subject : BiologyClass : XChapter : How do Organisms Reproduce?(Part-1)Topic : Asexual ReproductionTeacher