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REPRODUCTION IN ORGANISMS
Reproduction:a
...


b
...


c
...


Life span:-

a
...

Life span vary from short to the long organism to
organism
...
It is not necessary correlated with their sizes
...
g
...


Maximum life span:• It is the maximum number of years or the greatest
number of years, any organism of same species lived
...


Life expectancy:• An individual an expect how many years it can survive

❖ NOTE – maximum life span is the characteristics
features of the species and life expectancy is a
characteristics features of a population

Why reproduction is necessary?
•

Retain a particular species of living organisms
...


•

Variation leads to the origin of new species
...
g
...


❖

Relation with inheritance & variation : a house

map is considered as blueprint of house , similarly
body has a blueprint, which is DNA
...
Genes is located in chromosomes
...


Signification of variation:• Accumulation of variation over a period of time give
rise to new species
...


Type of reproduction:-

Asexual reproduction
•
Single parent is involved
•
No sexes are involved
• Growth rate is high
...
g
...


Sexual reproduction
• two parents involved
...

• Growth rate is slow
...
g
...


Asexual reproduction:
•
•
•
•
•
•

In this mode of reproduction new individual are
formed from a single parent
...

Faster mode of reproduction
...
g
...

Also seen in plant with similar organization
...
g
...


Types of asexual reproduction:
• Fission
• budding
• regeneration
• fragmentation
• spore formation
• vegetative propagation
Fission:
➢
an organism splits into two or more
individuals
...
Two individuals are formed
...
Nucleus divides only ones
...
Unicellular organisms like
amoeba, paramecium,
bacteria, use this process
...
It takes place under favourable
conditions
...
Many new individuals are
formed nucleus divided
respectively
...
Takes place in unfavourable
conditions(cyst formation takes
place )
...
Nucleus divided inside the cyst
...
Cyst act as a protective shield
in unfavourable condition
...
E
...
- plasmodium, many algae,
etc
...

➢ E
...
- hydra, yeast, sponges
...


➢ Seen in simple multicellular organism
➢ E
...
- spirogyra
...
g
...


Spore formation :➢ Formation of new 6individual by
germination of spores
...

➢ E
...
- conidia-non motile spores of
fungus(penicillium) termed as Mito
spores
...


Vegetative propagation:➢ Mode of asexual reproduction in
plants, simplest mode of reproduction
...

➢ It is also of two type:

• Natural
vegetative
propagation
...

• E
...
- guava, sweet
potato, dahlia
...

New plant arises at
the nodes
...
g
...

Under ground stems:

• E
...
- guava, sweet
potato, dahlia
By leaves:
• Buds are formed
along leaf margins
which later gives
rise to a new plant
...


By cutting:
• A plant is cut from
the parent and put
into the soil which
later give rise to a
new lant
...
g
...

Root cutting: dahlia
By layering:
• New plant are
formed by stem
of parent plant
without
detaching them
initially from the
parent
...
Mound
and air layering
...

(A)
...

(B)
...
This portion is
detached from main
plant
...

• Improves quality
of certain plants
...

• Two different
scion and from
same stock

Sexual reproduction:

• In this mode of
reproduction new individual
is formed from two parent
...

• Each individual in a
species has its own
uniqueness and identity
...


Why sexual reproduction?
• Sexual mode of reproduction is mainly seen
in higher organisms with complex body
organisms
• Generally seen in plants, animals & some
fungi
...

E
...
- wheat, carrot, rice, etc
...
g
...

→ In animals:
Seasonal breeders: once in a
season
E
...
- birds, lizards, frogs, etc
...

E
...
- poultry, rabbits, cattle’s, etc
...

→ In animals:
• Sex organs develops on maturity
...


Secondary sexual characters are:→ In males:
• Broadening of chest
• Change in voice

• Grown beard and moustaches
• Hair growth on chest and public
area
→ In females:
• Development of breast and hips
• Beginning of menstrual cycle

Cyclic changes observed in
female:a
...
Hormonal changes
→ Menstrual cycle:
Cyclic changes in females of primates
during reproductive phase
...

A
...

B
...


Puberty in human beings: period
during which the rate of general
body growth slows down and
reproductive tissue star maturing
...

Female- development of breast
and hips/beginning of menstrual
cycle/hair growth under armpits
and genital area
...

DNA:
• Deoxyribonucleic acid, it has a
double helix structure
...


Homogametic- in
some organisms male and female
gametes are identical to each
other
...

Male gametesthey are motile
Female gametestrarage of food

Fusion of male
and female gametes give rise to
new organisms
...


Gametogenesis:
formation of gametes
male gametes are
sperm and female
gametes are egg
...

Two type of plant
exist

A
...

E
...
papaya
and water
lemon
...
Bisexualcarries
both
reproductiv
e organs
(homothalli

c and
monoeciou
s)
...
g
...

→ In animals: two type
of animals exist
A
...

E
...
cockroach
and
human
male or
female
...
Bisexualcarries
both
reproducti
ve
organs(he
rmaphrodi
tes)
...
g
...


Moploid
and
diploid
→ Diploid: diploid is
donated by Zn
...
All
somatic cells are
diploid cells
...

the cell with one set
of chromosomes is
known as haploid
...


How are gametes formed?
→ If parent body is
releasing a
haploid(n)
There will be an
equational division
...
g
...

The gametes
formation takes place

with the help of
mitosis
...

The gametes
formation takes place
with the help of
meiosis
...
Transfer
of pollen grains
occurs from another
to stigma
...
Self pollination
B
...

Fertilization: fusion
of male and
female gametes
with female
gametes
...
Self pollination
B
...


Fertilization event :
Where does the fertilization ?
→ On the basis of
location
Fertilization occurs
as
A
...

B
...


External
fertilization : here
large number of
offspring are
reproduced
...

Internal fertilization
: it occurs inside
the body of
organism
...


Post-fertilization event :
This event occurs
after zygote
formation
...


Zygote formation :
fertilization results
the zygote which
is the diploid
fertilization egg
...
The
zygote under goes
mitotic cell division
and cell
differentiation
...
E
...

– birds
➢ Viviparous – zygote
develops inside
...
g
...

In plants : zygote
divides
respectively to
form an embryo
...
Ovule will
form a thick
coat(seed)
...

Structure enclosed
inside the seed is
embryo

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