Power Point Presentation for class XII biology students, Based on NCERT

1. Reproduction in Organisms
By: Nina Pandey

2. Life Span-
The period from birth to the natural death
of an organism .

4. Reproduction:
defined as a biological process in which an
organism gives rise to young ones (offspring)
similar to itself.
Factors responsible to show how organisms
reproduces?reproduces?
i) Habitat
ii) Its Internal physiology
iii) Several other factors collectively are
responsible.

5. Asexual reproduction:
•Offsprings produced by single parents.
•Without involvement of gamete formation
•Offsprings are genetically identical to
their parents.
•CLONE– organisms which are
morphologically and genetically similar.

6. Budding in Yeast

8. Methods of asexual reproduction:
Cell division as a method of asexual reproduction as in
Protista and Monera.
Binary fission e.g. Amoeba, Paramecium.
Budding: e.g. Yeast.
Asexual reproductive structures:
Zoospores: aquatic fungi, Chlamydomonas.Zoospores: aquatic fungi, Chlamydomonas.
Conidia: Penicillium.
Bud: Hydra
Gemmules: sponges.
Vegetative propagation units in plant: (Vegetative propagules)
Runner, rhizome, sucker, tuber, offset, bulb.

9. a) Zoospoe of Chlamydomonas, b) Conidia of Penicillium, c) Buds of Hydra, d)
Gemmules in sponge

10. a) Eyes of Potato, b) Rhizome of ginger c) Bulbil of Agave, d) Leaf buds of
Bryophyllum e) Offset of water hyacinth

12. •Sexual reproduction:
•Involvement of single or two individual.
•Production of male and female gametes ( haploid)
•Gametes fused to form a diploid zygote.•Gametes fused to form a diploid zygote.
•Zygotes developed into new organism.
•The offsprings are not genetically identical with their
parents

13. Features of sexual reproduction:
•Period between birth and sexual maturity is
called juvenile phase. It is known
as vegetative phase in plant.as vegetative phase in plant.
•Bamboo species flower only once in their life
time generally after 50-100 yr.
•Strobilanthus kunthiana (neelakranji) flowers
once in 12 years.

14. Oestrus cycle: cyclical changes during
reproduction in non-primate mammal like
cows, sheep, rats, deers, dogs, tiger etc.
Menstrual cycle: cyclical changes during
reproduction in primate mammals like
monkeys, ape, and humans.
Seasonal breeders: reproductive cycle takesSeasonal breeders: reproductive cycle takes
place in favourable seasons as in wild animals.
Continuous breeders: reproductively active
throughout their reproductive phase.

15. Pre Fertilisation Events-
i)Gametogenesisi)Gametogenesis
ii) Gamete Transfer

16. Gametogenesis
•Process of gamete formation is gametogenesis.
•Two gametes are similar in appearance are
called homogametes (isogametes).
•Gametes produced are of two morphologically•Gametes produced are of two morphologically
distinct types called heterogametes.
•Male gamete is
called antherozoids or sperm and the female
gamete is called ovum or egg.

17. Types of gametes: a) Isogametes of Cladophora ( an alga
Heterogametes b) Fucus ( an alga) c) Human beings

18. Sexuality in organism:
• Plant having both male and female sex organ
called homothallic or monoecious.
• Plants having only one sex organ is
called heterothallic or dioecious.
• In flowering plants, the unisexual male flower
is staminate, i.e. bearing staments, while theis staminate, i.e. bearing staments, while the
female is pistillate or bearing pistils.
• Animal having one type of reproductive system,
called unisexual.
• Animal having both male and female
reproductive system,
called hermaphrodite or bisexual.

19. Cell division during gamete formation:
• Gametes in all heterogametic species two
types namely male and female.
• Gametes are always haploid irrespective of
parent’s ploidy.
• A haploid parent produces gametes
by mitotic division.by mitotic division.
• Diploid parent produces gametes
by meiotic division.
• In diploid organisms specialized cells
called meiocytes (gamete mother cell)
undergo meiosis to produce haploid gametes.

20. Haplontic: Gametophytic phase dominant.
e.g., Chlamydomonas

21. Gamete transfer:
•Male and female gamete must be physically brought
together to facilitate fusion called fertilization.
•In most cases male gametes are motile, female
gametes are non-motile.
•In case of few fungi and algae, both male and female•In case of few fungi and algae, both male and female
gametes are motile.
•In most cases water is the medium for gamete
transfer.
•Male gametes are produced in several thousand
times the number of female gametes produced to
compensate the loss during transfer.

22. Fertilization:
• Fusion of male and female gamete is
called fertilization or syngamy.
• The female gamete undergoes
development to form new organismdevelopment to form new organism
without fertilization. This phenomenon
is called parthenogenesis.

23. Fertilisation cont…..
•Gametic fusion takes place outside the body i.e.
water is called external fertilization.
•Their must be synchrony of gamete release, large
number of gametes released to enhance the chance
of fertilization.
•Enable the individual to produce large number of•Enable the individual to produce large number of
offsprings.
•A major disadvantage is that the offsprings are
extremely vulnerable to predators.
•Fertilization takes place inside the body is
called internal fertilization.

24. Zygote:
• Formation of zygote after fertilization is
universal in all sexually reproducing organisms.
• Zygote is formed usually in water in case
of external fertilization.
• Zygote is formed inside the body of the
organism in internal fertilization.organism in internal fertilization.
• Zygote of fungi and algae develops a thick wall
that is resistant to dessication and damage.
• Organism with haplontic life cycle, zygote
undergoes meiosis to produce haploid spores.

25. Embryogenesis:
•Development of zygote into an embryo is
called embryogenesis.
•Zygote undergoes cell division (mitosis) and
cell differentiation.
•Oviparous animal which lays eggs and development takes
place inside egg.
•Viviparous animal gives birth to the young. The development•Viviparous animal gives birth to the young. The development
takes place inside the body of the female.
In plants:
Zygote developed into embryo.
Ovule developed into seed
Integument of the ovule developed into seed coat.
Ovary developed into fruit.
Ovary wall developed into pericarp.