CONCEPT The process offusion
development of new individuas through the
SEXUAL formation and of
male and female gametes is known
sexualreproduction or amphimixis or syngenesis.
as
MAP REPRODUCTION
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Sogamy agella
TYPES tinvolves the fusion of
gametes which do not differ PHASES OF LI
morphologically but may be
Syngamy different physiologicaly. t Juvenile/Vegetative phase
t is the complete and permanent fusion takes Place in Nucleus Itis pre-reproductive phase. The period of growth between the birth upto
of male and female gametes to form the Chlamydomonas. the reproductive maturity of an organism is called the juvenie phase. In -
zygote. plants, itisknown as vegetative phase.
Anisogamy
It involves the fusion of
Endogamy
tis the fusion of male and female Reproductive phaseJ
gametes which differ in size or
gametes of the same parent, form. It takes place in The
period when organisms start offspring
producing is called
hence, uniparentaleg. Toenia. Chamydomonas, red alge etc. reproductive phase. On the basis of it plant can be monocarpic (fiower
amete
only once in their life cycle, eg. bamboo) or polycarplc (fdower every year
Exogamy ina particular season, eg.apple).
t is the fusion of two gametes Oogamy On the basis oftime of breeding. animals are of two types:
produced by different parents, nvoves the tusion of large
hence, biparental e.9, Rabbit. non-motile female gamete Seasonal breeders These animals reproduce at a particudar period o
and a small motile male the year such as frog, lizard etc.
k in some Gi) Continuous breeders: These animas continue to breed throughout
Conjugation gamete. akes place
A process of
algae, vertebrates induding vum
their sexualmaturity eg. mice, cattle etc
organismssexual reproduction In
of the which
same species numan beings and higher
temorariv couole and exchange or in invertebrates.
Senescent phase
omecases transfer their genetic material. Hologamy tsthe
post-reproductive phase that begins from the end of the reproductive
t phase. The terminal irreversible stage of ageing is called senescence. k is the-
tbacterla
takes place in Paramoecium, Spirogyra,
involes the fusion of two organisms. It occurs in last phase of life span andulkimately leads to death.
etc. yeasts
EVENTS IN SEXUAL REPRODUCTION
Pre-fertilisationevents Fertilisation Post-fertilisationevents
hese events of sexual reproduction take place before the
of gametes. ihese indude:
It is the complete and permanent fusion of two gametes tinckudes devekopment and
of zygote embryogene
usion from different or same parent to form a diploid zy9ote
Development of zygote
syngamy.tcan be of twoypes.
Gametogenesls
t is the formation of gametes. Gametes can be
The zygote formed by fusion of two gametes is always
diploid. t is a link between one generation and next
External fertilsation
generation. The development of zygote depends upon the
sogametes (morphologically similar) or
When fertilisation occurs outside the body of the type of life cycle of the organisms and environmental
eterogametes (morphologically dissimilar). organism, t 5 called extemal ertisation or external
Gametes are formed asa result of meiosis which can syngamy. t requires an extemal medium such as wates,
conditions. There are three types of life cycles:
be of three types: eg. bony fish and amphibians.
g inside the sporangia
Sporic meiosis ocd Hapioid unicebular or
Sporophyte (2n)
Internal fertilsation
When egg is retained inside female body where it fuses
n Mitosis
ZYgote l2n) Sporangia (2 with the mae gamete. the process is caled internal
Meiosis fertilisation or Internal syngamy, eg. reptiles, birds,
mammalsetc
Ferilisation Melosis
Gamete n
Gamete in)
eid
Gametophyte Parthenogenesis MERDSB PEKTLISATON
Development of egg (ovum) into a omplete individual
(n)
occurs in
Gamec meiossocirnne e oemince
without fertilisation is known as parthenogenesis.t
rotifers, arthropods, insects etc.Itisof two types:
2n
Diplold
halus izn)
Naturel Diplontic life cyde oe
Roccurs regularly in the life cyde of certain animas. t
in
Gametle
can be complete (occurs animals which breed GAmetes
weiOSIS
Gameta
exclusively
n
by parthenogenesis), incomplete(occurs
(2n)
animals in which both
parthenogenesis oco
sexual reproduction and
and paedogenetic (occurs in
Melósts larva). MEDSS FERTAISATION
mete (n) Gamete (n
plod
Artifical
h
this type, the ovum is induced to develop intopa
complete individual by artificial stimuli. The stimuli
Haploid cells (n)
2n
can be physical or chemical Ygote
Haploid thallus (n) Emoyo
Mejósis
Zygote l2n) ( ygotc
Neoteny Mitoss
When the lara retains aduk characters such as gonads and ontic liteC
Melosls teridophy
on
dmetanga (n) strts producing young ones by sexual reproduction, R saed
neoteny. Roccurs in axolotllarva
Haploid mubiceluar
rganism 9etop"ye
aaTete in
o o n e t e tD
Mtoss
Embryogeness
Gamete transfer During embryogenesis zygote undergoes mitotic cel
Spores
and
tis the transfer of gametes to bring them together division cell diterentiation. on the basis of
evelbpment of zygote animals can be oviparous
for fertilisation. In algae, bryophytes and
pteridophytes water serves as the medium. In 99-laying: zygote develop5 outside the female body) MEXOSS FERTIUSATO
flowering plants it is done by pollination. Animals eg. all birds. most reptiles etc, viviparous (zygote Diploid
havecopulatoryorgansto transfer male gametes. develops inside the femae body) eg. mammas (except
egg laying mammals) or ovoviviparous (retains egg
uno
Sporopa
inside;zygote development is internaleg.sharks
Ihflowering plants, zygote is formed inside the ovule
SPECIAL MODES OF REPRODUCTION After fertilisation the ripened ovary forms the fruit. The
ovules mature and get converted into seeds. The ovary
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EOs's
wall produces pericarp which protects the seeds.
