How do Organisms Reproduce - Class 10 PDF Download

 Page 1


How do Organisms Reproduce
Introduction
? Reproduction is a very important biological process for all organisms in the
continuity of the generations.
? There are different types of living species existing on this planet earth. Few are a
single-celled organism, some are multicellular organisms while few species lack
a true nucleus and other cell organelles.
? Reproduction varies with the species.
? Over the years, we have two primary ways for organisms to reproduce - sexual
and asexual reproduction.
? Almost all of the higher organisms use the sexual mode of reproduction to ensure
lineage and continuity of species.
Importance of Variation
? The chapter on “How do organisms reproduce” notes that DNA varies from
person to person.
? It’s the genetic element that affects our body structure, including morphology and
physiology, ultimately leading to each human being’s uniqueness.
? DNA (DeoxyriboNucleic Acid), molecules existing in chromosomes that contain
information about the inheritance of features through generations.
? Variation is useful for the survival of species over time.
? If a population of reproducing organisms were suited for a particular niche and if
the niche were drastically altered, the population could be wiped out.
? But if some variations were to be present in a few individuals in these
populations, there would be some chance for them to survive.
What is Reproduction?
? Reproduction is the biological process in which every living organisms give rise
to their young ones which are identical to their parents.
? The process of reproduction involves DNA copying, which refers to the hereditary
transfer of genes.
? The nucleus of the cell contains DNA which is the hereditary material.
? DNA replicates and forms new cells causing variations. So, these cells new cells
will be similar but may not be identical to the original cell.
? The variations are useful for the survival of the individual and species over time
as well as basis for evolution.
Page 2


How do Organisms Reproduce
Introduction
? Reproduction is a very important biological process for all organisms in the
continuity of the generations.
? There are different types of living species existing on this planet earth. Few are a
single-celled organism, some are multicellular organisms while few species lack
a true nucleus and other cell organelles.
? Reproduction varies with the species.
? Over the years, we have two primary ways for organisms to reproduce - sexual
and asexual reproduction.
? Almost all of the higher organisms use the sexual mode of reproduction to ensure
lineage and continuity of species.
Importance of Variation
? The chapter on “How do organisms reproduce” notes that DNA varies from
person to person.
? It’s the genetic element that affects our body structure, including morphology and
physiology, ultimately leading to each human being’s uniqueness.
? DNA (DeoxyriboNucleic Acid), molecules existing in chromosomes that contain
information about the inheritance of features through generations.
? Variation is useful for the survival of species over time.
? If a population of reproducing organisms were suited for a particular niche and if
the niche were drastically altered, the population could be wiped out.
? But if some variations were to be present in a few individuals in these
populations, there would be some chance for them to survive.
What is Reproduction?
? Reproduction is the biological process in which every living organisms give rise
to their young ones which are identical to their parents.
? The process of reproduction involves DNA copying, which refers to the hereditary
transfer of genes.
? The nucleus of the cell contains DNA which is the hereditary material.
? DNA replicates and forms new cells causing variations. So, these cells new cells
will be similar but may not be identical to the original cell.
? The variations are useful for the survival of the individual and species over time
as well as basis for evolution.
? While studying the How do Organisms reproduce class 10 notes, you will learn
about the various methods of reproduction that cause significant variations.
Types of Reproduction
There are two main types of Reproduction.
1) Asexual Reproduction
2) Sexual Reproduction
Asexual Reproduction
? It involves only one parent.
? There is no formation and fusion of gametes.
? The young ones formed are almost identical to each other as well as to the
parent cell.
? Asexual reproduction generally occurs during favourable environmental
conditions and when there is an abundance of food.
? It is a faster method of reproduction.
Types of Asexual Reproduction is Unicellular Organism-
Binary Fission
? Seen in bacteria, protozoa like Amoeba, Paramecium.
? (In these ?rst pseudopodia withdrawn (karyokinesis) the nucleus of the parent
cell divides and then the cytoplasm divides (cytokinesis) resulting in the
formation of two daughter cells).
? It occurs during highly favourable conditions.
? The cell division can occur in any plane as in case of Amoeba.
? However, organisms like Leishmania. (cause Kala-azar), which have a whip like
?agella at one end, binary ?ssion occurs in a de?nite orientation in relation to the
?agellum.
Binary Fission in Amoeba
Page 3


How do Organisms Reproduce
Introduction
? Reproduction is a very important biological process for all organisms in the
continuity of the generations.
? There are different types of living species existing on this planet earth. Few are a
single-celled organism, some are multicellular organisms while few species lack
a true nucleus and other cell organelles.
? Reproduction varies with the species.
? Over the years, we have two primary ways for organisms to reproduce - sexual
and asexual reproduction.
? Almost all of the higher organisms use the sexual mode of reproduction to ensure
lineage and continuity of species.
Importance of Variation
? The chapter on “How do organisms reproduce” notes that DNA varies from
person to person.
? It’s the genetic element that affects our body structure, including morphology and
physiology, ultimately leading to each human being’s uniqueness.
? DNA (DeoxyriboNucleic Acid), molecules existing in chromosomes that contain
information about the inheritance of features through generations.
? Variation is useful for the survival of species over time.
? If a population of reproducing organisms were suited for a particular niche and if
the niche were drastically altered, the population could be wiped out.
? But if some variations were to be present in a few individuals in these
populations, there would be some chance for them to survive.
What is Reproduction?
? Reproduction is the biological process in which every living organisms give rise
to their young ones which are identical to their parents.
? The process of reproduction involves DNA copying, which refers to the hereditary
transfer of genes.
? The nucleus of the cell contains DNA which is the hereditary material.
? DNA replicates and forms new cells causing variations. So, these cells new cells
will be similar but may not be identical to the original cell.
? The variations are useful for the survival of the individual and species over time
as well as basis for evolution.
? While studying the How do Organisms reproduce class 10 notes, you will learn
about the various methods of reproduction that cause significant variations.
Types of Reproduction
There are two main types of Reproduction.
1) Asexual Reproduction
2) Sexual Reproduction
Asexual Reproduction
? It involves only one parent.
? There is no formation and fusion of gametes.
? The young ones formed are almost identical to each other as well as to the
parent cell.
? Asexual reproduction generally occurs during favourable environmental
conditions and when there is an abundance of food.
? It is a faster method of reproduction.
Types of Asexual Reproduction is Unicellular Organism-
Binary Fission
? Seen in bacteria, protozoa like Amoeba, Paramecium.
? (In these ?rst pseudopodia withdrawn (karyokinesis) the nucleus of the parent
cell divides and then the cytoplasm divides (cytokinesis) resulting in the
formation of two daughter cells).
? It occurs during highly favourable conditions.
? The cell division can occur in any plane as in case of Amoeba.
? However, organisms like Leishmania. (cause Kala-azar), which have a whip like
?agella at one end, binary ?ssion occurs in a de?nite orientation in relation to the
?agellum.
Binary Fission in Amoeba
Multiple Fission
? Seen in Plasmodium, (a malarial parasite).
? In this during unfavourable conditions, the parent cell develops a thick resistant
wall around itself forming a cyst.
? Within the wall, the cytoplasm divides many times to form many plasmodia.
? When conditions become favourable, the cyst wall breaks and the Plasmodium
are released.
Multiple Fission
Budding
? Seen in Yeast (a fungus).
? The parent yeast cell develops a protrusion or an outgrowth at its upper end.
? The nucleus of the parent cell divides and one of them moves into the outgrowth
which grows bigger and ?nally separates from the parent cell to lead an
independent existence.
? Very often if the conditions are highly favourable, a chain of buds is formed.
Budding in Yeast
Types of Asexual Reproduction in Multicellular Organisms-
Page 4


How do Organisms Reproduce
Introduction
? Reproduction is a very important biological process for all organisms in the
continuity of the generations.
? There are different types of living species existing on this planet earth. Few are a
single-celled organism, some are multicellular organisms while few species lack
a true nucleus and other cell organelles.
? Reproduction varies with the species.
? Over the years, we have two primary ways for organisms to reproduce - sexual
and asexual reproduction.
? Almost all of the higher organisms use the sexual mode of reproduction to ensure
lineage and continuity of species.
Importance of Variation
? The chapter on “How do organisms reproduce” notes that DNA varies from
person to person.
? It’s the genetic element that affects our body structure, including morphology and
physiology, ultimately leading to each human being’s uniqueness.
? DNA (DeoxyriboNucleic Acid), molecules existing in chromosomes that contain
information about the inheritance of features through generations.
? Variation is useful for the survival of species over time.
? If a population of reproducing organisms were suited for a particular niche and if
the niche were drastically altered, the population could be wiped out.
? But if some variations were to be present in a few individuals in these
populations, there would be some chance for them to survive.
What is Reproduction?
? Reproduction is the biological process in which every living organisms give rise
to their young ones which are identical to their parents.
? The process of reproduction involves DNA copying, which refers to the hereditary
transfer of genes.
? The nucleus of the cell contains DNA which is the hereditary material.
? DNA replicates and forms new cells causing variations. So, these cells new cells
will be similar but may not be identical to the original cell.
? The variations are useful for the survival of the individual and species over time
as well as basis for evolution.
? While studying the How do Organisms reproduce class 10 notes, you will learn
about the various methods of reproduction that cause significant variations.
Types of Reproduction
There are two main types of Reproduction.
1) Asexual Reproduction
2) Sexual Reproduction
Asexual Reproduction
? It involves only one parent.
? There is no formation and fusion of gametes.
? The young ones formed are almost identical to each other as well as to the
parent cell.
? Asexual reproduction generally occurs during favourable environmental
conditions and when there is an abundance of food.
? It is a faster method of reproduction.
Types of Asexual Reproduction is Unicellular Organism-
Binary Fission
? Seen in bacteria, protozoa like Amoeba, Paramecium.
? (In these ?rst pseudopodia withdrawn (karyokinesis) the nucleus of the parent
cell divides and then the cytoplasm divides (cytokinesis) resulting in the
formation of two daughter cells).
? It occurs during highly favourable conditions.
? The cell division can occur in any plane as in case of Amoeba.
? However, organisms like Leishmania. (cause Kala-azar), which have a whip like
?agella at one end, binary ?ssion occurs in a de?nite orientation in relation to the
?agellum.
Binary Fission in Amoeba
Multiple Fission
? Seen in Plasmodium, (a malarial parasite).
? In this during unfavourable conditions, the parent cell develops a thick resistant
wall around itself forming a cyst.
? Within the wall, the cytoplasm divides many times to form many plasmodia.
? When conditions become favourable, the cyst wall breaks and the Plasmodium
are released.
Multiple Fission
Budding
? Seen in Yeast (a fungus).
? The parent yeast cell develops a protrusion or an outgrowth at its upper end.
? The nucleus of the parent cell divides and one of them moves into the outgrowth
which grows bigger and ?nally separates from the parent cell to lead an
independent existence.
? Very often if the conditions are highly favourable, a chain of buds is formed.
Budding in Yeast
Types of Asexual Reproduction in Multicellular Organisms-
Fragmentation
? Seen in multicellular organisms which have a relatively simple body organisation
like Spirogyra.
? Spirogyra has a ?lamentous body. (If it breaks into smaller pieces or fragments).
Each fragment has the capacity to form a new individual.
? However, all multicellular organisms cannot show cell-by-cell division as cells
from tissues which form organs.
? These organs are placed at de?nite positions in the body. Hence, they need to
use more complex methods of reproduction.
Regeneration
? It is the ability of organisms to develop their lost parts.
? Some organisms show high regenerative capacity.
? It is also a means of reproduction for example in Planaria-
? Regeneration is carried out by specialized cells which redivide to form a mass of
cells from which different cells undergo changes to become different cell types
and tissues.
? These changes occur in an organized sequence known as development.
Page 5


How do Organisms Reproduce
Introduction
? Reproduction is a very important biological process for all organisms in the
continuity of the generations.
? There are different types of living species existing on this planet earth. Few are a
single-celled organism, some are multicellular organisms while few species lack
a true nucleus and other cell organelles.
? Reproduction varies with the species.
? Over the years, we have two primary ways for organisms to reproduce - sexual
and asexual reproduction.
? Almost all of the higher organisms use the sexual mode of reproduction to ensure
lineage and continuity of species.
Importance of Variation
? The chapter on “How do organisms reproduce” notes that DNA varies from
person to person.
? It’s the genetic element that affects our body structure, including morphology and
physiology, ultimately leading to each human being’s uniqueness.
? DNA (DeoxyriboNucleic Acid), molecules existing in chromosomes that contain
information about the inheritance of features through generations.
? Variation is useful for the survival of species over time.
? If a population of reproducing organisms were suited for a particular niche and if
the niche were drastically altered, the population could be wiped out.
? But if some variations were to be present in a few individuals in these
populations, there would be some chance for them to survive.
What is Reproduction?
? Reproduction is the biological process in which every living organisms give rise
to their young ones which are identical to their parents.
? The process of reproduction involves DNA copying, which refers to the hereditary
transfer of genes.
? The nucleus of the cell contains DNA which is the hereditary material.
? DNA replicates and forms new cells causing variations. So, these cells new cells
will be similar but may not be identical to the original cell.
? The variations are useful for the survival of the individual and species over time
as well as basis for evolution.
? While studying the How do Organisms reproduce class 10 notes, you will learn
about the various methods of reproduction that cause significant variations.
Types of Reproduction
There are two main types of Reproduction.
1) Asexual Reproduction
2) Sexual Reproduction
Asexual Reproduction
? It involves only one parent.
? There is no formation and fusion of gametes.
? The young ones formed are almost identical to each other as well as to the
parent cell.
? Asexual reproduction generally occurs during favourable environmental
conditions and when there is an abundance of food.
? It is a faster method of reproduction.
Types of Asexual Reproduction is Unicellular Organism-
Binary Fission
? Seen in bacteria, protozoa like Amoeba, Paramecium.
? (In these ?rst pseudopodia withdrawn (karyokinesis) the nucleus of the parent
cell divides and then the cytoplasm divides (cytokinesis) resulting in the
formation of two daughter cells).
? It occurs during highly favourable conditions.
? The cell division can occur in any plane as in case of Amoeba.
? However, organisms like Leishmania. (cause Kala-azar), which have a whip like
?agella at one end, binary ?ssion occurs in a de?nite orientation in relation to the
?agellum.
Binary Fission in Amoeba
Multiple Fission
? Seen in Plasmodium, (a malarial parasite).
? In this during unfavourable conditions, the parent cell develops a thick resistant
wall around itself forming a cyst.
? Within the wall, the cytoplasm divides many times to form many plasmodia.
? When conditions become favourable, the cyst wall breaks and the Plasmodium
are released.
Multiple Fission
Budding
? Seen in Yeast (a fungus).
? The parent yeast cell develops a protrusion or an outgrowth at its upper end.
? The nucleus of the parent cell divides and one of them moves into the outgrowth
which grows bigger and ?nally separates from the parent cell to lead an
independent existence.
? Very often if the conditions are highly favourable, a chain of buds is formed.
Budding in Yeast
Types of Asexual Reproduction in Multicellular Organisms-
Fragmentation
? Seen in multicellular organisms which have a relatively simple body organisation
like Spirogyra.
? Spirogyra has a ?lamentous body. (If it breaks into smaller pieces or fragments).
Each fragment has the capacity to form a new individual.
? However, all multicellular organisms cannot show cell-by-cell division as cells
from tissues which form organs.
? These organs are placed at de?nite positions in the body. Hence, they need to
use more complex methods of reproduction.
Regeneration
? It is the ability of organisms to develop their lost parts.
? Some organisms show high regenerative capacity.
? It is also a means of reproduction for example in Planaria-
? Regeneration is carried out by specialized cells which redivide to form a mass of
cells from which different cells undergo changes to become different cell types
and tissues.
? These changes occur in an organized sequence known as development.
Budding
? Seen in Hydra.
? Parent Hydra develops a bud at its lower end.
? This grows in size and ?nally breaks off to live independently.
Spore Formation
? Seen in Rhizopus (a fungus).
? Rhizopus body is made up of thread-like structures called hyphae.
? The erect hyphae bear sporangia inside which reproductive structures called
spores are formed.
? Spores are asexually reproducing bodies having a thick protective wall.
? They are produced during unfavourable times and help to tide over the
unfavourable environmental conditions.
? When the spores fall on a suitable medium, each one forms a new individual.
Spore formation in Rhizopus
Vegetative Propagation