01.
REPRODUCTION
Reproduction :
i) Formation of new organism of same species by earlier existing organism is
called as reproduction.
ii) Reproduction is one of the various important characters of living organisms.
Reproduction does not help the organism to remain alive but it helps to
iii) maintain the continuity of the species of that organism & ecosystem.
iv) Those two methods are- asexual and sexual reproduction.
I) Asexual reproduction :
i) Process of formation of new organism by an organism of same species
without involvement of gametes is called as asexual reproduction.
ii) This reproduction does not involve union of two different gametes
iii) This is uniparental reproduction
iv) In this type of reproduction, mitotic cell division take place.
v) drawback : Absence of genetic recombination
A. Asexual reproduction in unicellular organisms :
1. Binary Fission : Simple binary fission: Amoeba
Parent Amoeba Daughter
Daughter
Parent paramoecium paramoecium
Longitudinal binary
fission: Euglena
Transverse binary fission : Paramecium
, 02.
i) In this process, the parent cell divides to form two similar daughter cells.
Binary fission occurs either by mitosis or amitosis.
ii) E.g : Prokaryotes (Bacteria), Protists (Amoeba, Paramoecium, Euglena, etc.)
iii) Eukaryotic cell-organelle like mitochondria and chloroplasts etc.
iv) Axis of fission / division is different in different protists.
v) This process performed by living organisms during favorable conditions
i.e. availability of abundant food material.
2. Multiple Fission :
stops the formation of pseudopodia due to lack of food
Parent Amoeba Division of nucleus and cytoplasm
Cyst : (protective
covering around Daughter
plasma membrane) amoeba
i) Amoeba, Plasmodium and other similar protists are performed multiple fission.
ii) Condition : Amoeba stops the formation of pseudopodia and thereby
movements due to there is lack of food or any other type of adverse condition.
iii) So it becomes rounded and forms protective covering around plasma
membrane. This is called as ‘Cyst’.
iv) Many nuclei are formed by repeated nuclear divisions in the cyst. It is
followed by cytoplasmic division and thus, many amoebulae are formed.
v) Cyst breaks open on arrival of favorable conditions and many amoebulae
are released.
3. Budding :
New Bud Daughter yeast
Bulge
Parent yeast
cell
, 03.
Process : i) Reproduction of yeast- a unicellular fungus occurs by budding.
ii) Yeast cell produces two daughter nuclei by mitotic division, so as to
reproduce by budding.
iii) A small bulge appears on the surface of parent cell. This bulge is actually a
bud.
iv) One of the two daughter nuclei enters this bud.
v) After sufficient growth, bud separates from the parent cell and starts to live
independently as a daughter yeast cell.
B. Asexual reproduction in Multicellular organisms :
1. Fragmentation:
1) The body of parent organism breaks up into
many fragments and each fragment starts to
Spirogyra
live as an independent new organism.
2) E.g : Spirogyra, and sponges like Sycon.
3) Condition : i) Whenever there is plenty of
water and nutrients are available to Spirogyra, its
filaments grow up very fast and break up into
many small fragments.
ii) Sycon breaks up accidentally into many
fragments, each fragment develops into new Sycon.
2. Regeneration :
1) Some living organisms breaks up its body into two parts and thereafter each
part regenerates remaining part of the body and thus two new living organisms
are formed. This is called as regeneration.
2) E.g : Planaria
Planaria
REPRODUCTION
Reproduction :
i) Formation of new organism of same species by earlier existing organism is
called as reproduction.
ii) Reproduction is one of the various important characters of living organisms.
Reproduction does not help the organism to remain alive but it helps to
iii) maintain the continuity of the species of that organism & ecosystem.
iv) Those two methods are- asexual and sexual reproduction.
I) Asexual reproduction :
i) Process of formation of new organism by an organism of same species
without involvement of gametes is called as asexual reproduction.
ii) This reproduction does not involve union of two different gametes
iii) This is uniparental reproduction
iv) In this type of reproduction, mitotic cell division take place.
v) drawback : Absence of genetic recombination
A. Asexual reproduction in unicellular organisms :
1. Binary Fission : Simple binary fission: Amoeba
Parent Amoeba Daughter
Daughter
Parent paramoecium paramoecium
Longitudinal binary
fission: Euglena
Transverse binary fission : Paramecium
, 02.
i) In this process, the parent cell divides to form two similar daughter cells.
Binary fission occurs either by mitosis or amitosis.
ii) E.g : Prokaryotes (Bacteria), Protists (Amoeba, Paramoecium, Euglena, etc.)
iii) Eukaryotic cell-organelle like mitochondria and chloroplasts etc.
iv) Axis of fission / division is different in different protists.
v) This process performed by living organisms during favorable conditions
i.e. availability of abundant food material.
2. Multiple Fission :
stops the formation of pseudopodia due to lack of food
Parent Amoeba Division of nucleus and cytoplasm
Cyst : (protective
covering around Daughter
plasma membrane) amoeba
i) Amoeba, Plasmodium and other similar protists are performed multiple fission.
ii) Condition : Amoeba stops the formation of pseudopodia and thereby
movements due to there is lack of food or any other type of adverse condition.
iii) So it becomes rounded and forms protective covering around plasma
membrane. This is called as ‘Cyst’.
iv) Many nuclei are formed by repeated nuclear divisions in the cyst. It is
followed by cytoplasmic division and thus, many amoebulae are formed.
v) Cyst breaks open on arrival of favorable conditions and many amoebulae
are released.
3. Budding :
New Bud Daughter yeast
Bulge
Parent yeast
cell
, 03.
Process : i) Reproduction of yeast- a unicellular fungus occurs by budding.
ii) Yeast cell produces two daughter nuclei by mitotic division, so as to
reproduce by budding.
iii) A small bulge appears on the surface of parent cell. This bulge is actually a
bud.
iv) One of the two daughter nuclei enters this bud.
v) After sufficient growth, bud separates from the parent cell and starts to live
independently as a daughter yeast cell.
B. Asexual reproduction in Multicellular organisms :
1. Fragmentation:
1) The body of parent organism breaks up into
many fragments and each fragment starts to
Spirogyra
live as an independent new organism.
2) E.g : Spirogyra, and sponges like Sycon.
3) Condition : i) Whenever there is plenty of
water and nutrients are available to Spirogyra, its
filaments grow up very fast and break up into
many small fragments.
ii) Sycon breaks up accidentally into many
fragments, each fragment develops into new Sycon.
2. Regeneration :
1) Some living organisms breaks up its body into two parts and thereafter each
part regenerates remaining part of the body and thus two new living organisms
are formed. This is called as regeneration.
2) E.g : Planaria
Planaria
