By Rehet Kaur Bhatia 8D . This is created With a lot of patience and hard work And is not to scale. this chapter is Intrusting and teaches us alot of things.

1. CHAPTER 9
[REPRODUCTION IN
ANIMALS ] CLASS 8
By Rehet Kaur Bhatia 8D
This Photo by Unknown Author is licensed under CC BY-SA

2. REPRODUCTION AND IT’S
TYPES
• Reproduction -: A biological process in which offsprings are
produced by their parents.
• Reproduction can be of 2 types -:
a. Sexual reproduction: when two parents are involved in
reproduction and gamete formation is necessary for
reproduction, it is called sexual reproduction.
b.Asexual reproduction: when a single parent is involved in
reproduction and gamete formation does not take place, it
is called asexual reproduction.

3. HUMAN REPRODUCTIVE SYSTEM
• Human Reproductive System
• Female Reproductive Organs: The female
reproductive organs are a pair of ovaries, a pair
of oviducts (fallopian tubes) and a uterus. The
female gametes, i.e. eggs are produced by
ovaries.
• Male Reproductive Organs: The male
reproductive organs are a pair of testes, two
sperm ducts and a penis. Testes produce the
male gametes which are called sperms.
• Structure of Sperm: A sperm is very small in
size, unicellular, and is composed of a head,
middle piece and a tail.

4. FERTILIZATION AND IT’S
TYPES
• Fertilization : Fusion of a male gamete with a female gamete is
called fertilization. During fertilization, fusion of nuclei of sperm and
egg takes place. Zygote is formed after fertilization.
• Types of fertilization
 External Fertilization: When fertilization takes place outside the
animal’s body, is external fertilization. Most of the aquatic animals
show external fertilization .Many eggs need to be fertilized in this
method because most of the fertilized eggs get washed away by
water Large number of eggs ensures survival of some of the
offspring.
 Internal Fertilization: When fertilization takes place inside the
animal’s body, it is called internal fertilization Unlike external
fertilization, there is no need to produce a lot of eggs in internal
fertilization. This Photo by Unknown Author is licensed under CC BY-SA

5. EMBRYO , FOETUS AND IVF
• Embryo: After conception, the ball of cells undergoes further
rounds of cell division. During the process, the cells begin to
differentiate into different types of tissue. Tissue level stage after
conception is called embryo.
• Foetus : When the embryo begins to resemble a human being, it
is called a foetus. At this stage, various external organs; like legs,
head, ear, eyes, etc. become apparent.
• IVF (In Vitro Fertilization): Any biological process carried out in
laboratory is called in-vitro. Thus, fertilization carried out in
laboratory is called in-vitro fertilization. After in-vitro fertilization,
zygote can develop into a mass of cells and is then transferred into
the uterus for subsequent development. Many women may fail to
conceive due to certain problems. In-vitro fertilization helps such
women to bear a child. A baby which is born with the help of this
technique is often called the ‘test tube baby This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY

6. FORMATION OF EGG SHELL IN
HENS
Formation of Egg Shell in Hens: We know
that birds and many other animals lay eggs.
Eggs of these animals have a tough shell of
calcium carbonate. When zygote travels
down the fallopian tubes, it undergoes
several rounds of cell division. Many
protective layers are formed around the
zygote during this process. These layers
subsequently develop into the hard shell of
egg. The hen lays an egg only when the shell
is completely formed. The embryo inside the
egg of a hen takes about 3 weeks to develop
into a chick.
This Photo by Unknown Author is licensed under CC BY-SA

7. OVIPAROUS AND VIVIPAROUS
ANIMALS
a.Oviparous Animals: Animals which lay eggs
are called oviparous animals, e.g. birds and
most of the reptiles.
b.Viviparous Animals: Animals which give birth to
young ones are called viviparous animals, e.g.
most of the mammals and some fish.

8. METAMORPHOSIS
• Metamorphosis: In case of indirect
development, transformation of young ones
into adult is called metamorphosis. Larva of
butterfly undergoes metamorphosis to
become a butterfly. A tadpole undergoes
metamorphosis to become a frog.
• Dramatic change in the form and often the
habits of an animal during its development
after birth or hatching. The transformation
of a maggot into an adult fly, and of a
tadpole into an adult frog, are examples
of metamorphosis.

9. TYPES OF ASEXUAL
REPRODUCTION
• Budding:Thismethodisseeninmulticellularanimalswhicharehighlysimplein
structure.Asmallbuddevelopsonthebody.Thebuddevelopsandstartsresembling
itsmother.Afterthat,thebudgetsdetachedfromthemother’sbodytobeginlifeasa
newindividual.Examples:Hydraandsponges.
• BinaryFission:Thismethodisseeninunicellularanimals.Thecellofamoebadivided
intotwodaughtercells.Eachdaughtercellbecomesanewindividual.
• Cloning:Whenanewcellorapartofanorganismorthewholeorganismisproduced
fromacell,itiscalledcloning.Asheepwasthefirstmammaltobecloned.Itwas
namedasDolly.IanWilmutandhiscolleaguesatRoslinInstituteinEdinburgh
(Scotland)clonedDollyin1996.Forthis,thescientiststookacellfrommammary
glandfromasheepandtookeggfromanothersheep.Theyremovedthenucleusofthe
eggandreplaceditwithnucleusofthecellfrommammarygland.Afterthat,theegg
wastransplantedintotheuterusofsheep.Theeggsubsequentlydevelopedintoa
cloneinduecourseoftime.