Biology PowerPoint Presentation

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Saksham singh VIII B8228

Reproduction in AnimalChapter :-9

Modes of ReproductionSexual Reproduction

This types of Reproduction in which Two parents(Male and Female) are Required.

Asexual ReproductionThis types of Reproduction in which only One parents are Required.

DISTINUISH

Sexual Reproduction•Example:-Human•Only Two parent (Male and Female)are requred.•fusion of sex cell (gametes) take place.•complex

Asexual Reproduction•Example:-Amoeba•Only one parent are requred.•No fusion of gametes.•Simple

Male Reproductive OrgansThe male reproductive organs include apair of testes (singular, testis), two spermducts and a penis . The testesproduce the male gametes called Sperm.

Head

Middle Part

Tail

Human sperm

Penis

Testis

Sperm Duct

Male reproductive organs in humans

The female reproductive organs are a pairof ovaries, oviducts (fallopian tubes) andthe uterus . Ovary produces female gametes called ova (eggs). In human beings, a singlematured egg is released into the oviductby one of the ovaries every month.Uterus is the part where development ofthe baby takes place. Like the sperm,an egg is also a single cell.

Female Reproductive Organs

Oviduct

Ovary

Uterus

Female Reproduction Organ

Human Ovum

Nucleus

FertilizationSuch fusion ofthe egg and the sperm is calledfertilization .

Internal FertilisationExample:- humans, cows, dogs , Donkey etc .

Fertilisation Inside in Female body.External FertilisationExample:- Frog.

Fertilisation Outside in Female body.

Fusingnuclei

Zygote

In some womenoviducts are blocked. These womenare unable to bear babies becausesperms cannot reach the egg forfertilization. In such cases, doctorscollect freshly released egg andsperms and keep them together for afew hours for IVF or in vitrofertilization (fertilization outside thebody). In case fertilization occurs, thezygote is allowed to develop for abouta week and then it is placed in themother’s uterus. Completedevelopment takes place in the uterusand the baby is born like any otherbaby. Babies born through thistechnique are called test-tubebabies. This term is actuallymisleading because babies cannotgrow in test tubes.

TEST TUBE BABIES

Though these animals layhundreds of eggs and releasemillions of sperms, all the eggsdo not get fertilized and developinto new individuals.This is because the eggs andsperms get exposed to watermovement, wind and rainfall.Also, there are other animals inthe pond which may feedon eggs. Thus, productionof large number of eggs andsperms is necessary toensure fertilizationof at leasta few of them.

Interesting Fact

Development of Embryo

Ball of cells (Enlarge).

Fertilization results in the formation ofzygote which begins to develop into anembryo .The zygote dividesrepeatedly to give rise to a ball of cells. The cells then begin to formgroups that develop into different tissuesand organs of the body. This developingstructure is termed an embryo. Theembryo gets embedded in the wall of theuterus for further development The embryo continues to develop inthe uterus. It gradually develops the body parts such as hands, legs, head,eyes, ears, etc. The stage of the embryoin which all the body parts can beidentified is called a foetus . When the development of the foetus iscomplete, the mother gives birth to the baby

Zygote formation and development of an embryo from the zygote

Embedding of the embryo in the uterus (enlarged)

Zygote

Foetus in the uterus

Viviparous and Oviparous AnimalsSome animals givebirth to young ones while some animalslay eggs which later develop into youngones. The animals which give birth toyoung ones are called viviparousanimals. Those animals which lay eggsare called oviparous animals. The eggs of a few animals are easyto collect because their mothers laythem outside their bodies. Theseanimals from which you have collectedthe eggs are examples of oviparousanimals. But you would not be able tocollect the eggs of a dog, cow or cat.This is because they do not lay eggs.The mother gives birth to the youngones. These are examples of viviparous animals.

DISTINGUISH

Oviparous•Example:-Craw•Those Animals which lay eggs.

Viviparous•Example:-Dog, Horse etc.•Those Animals which gives birth to young ones.

The new individuals which are born orhatched from the eggs continue to growtill they become adults. In someanimals, the young ones may look verydifferent from the adults. Recall the lifecycle of the silkworm (egg → larva orcaterpillar → pupa → adult) Frog is another such example.

Young Ones to Adults

Life of FrogThe different stages of frogstarting from the egg to the adult stage.We find that there are three distinctstages, that is, egg → tadpole (larva) → AdultThe transformation of the larva into an adultthrough drastic changes is calledmetamorphosis.

Life cycle of frog

Asexual Reproduction

Budding in HydraIn each hydra, there may be one or more bulges. These bulges are the developing new individuals and they arecalled buds.

This types of Reproduction in which only One parents are Required.

In hydra too the new individuals develop as outgrowths from a single parent. This type of reproduction in which only a single parent is involved is called

Asexual reproduction

Newindividuals develop from the buds inhydra, this type of asexual reproduction

is called budding.

This type of asexual reproduction in which an animalreproduces by dividing into twoindividuals is called Binary fission.

a

b

c

d

Dividing nucleus

Daughter amoebae

Binary fission in Amoeba

Story of Dolly, the CloneThen, the nucleus of the mammary gland cell from the Finn Dorsett sheepwas inserted into the egg of the Scottish blackface ewe whose nucleus had beenremoved. The egg thus produced was implanted into the Scottish blackface ewe.Development of this egg followed normally and finally Dolly was born. ThoughDolly was given birth by the Scottish blackface ewe, it was found to be absolutelyidentical to the Finn Dorsett sheep from which the nucleus was taken. Since thenucleus from the egg of the Scottish blackface ewe was removed, Dolly did notshow any character of the Scottish blackface ewe. Dolly was a healthy clone ofthe Finn Dorsett sheep and produced several offspring of her own through

Cloning is the production of an exact copy of a cell, any other living part, or acomplete organism. Cloning of an animal was successfully performed for the firsttime by Ian Wilmot and his colleagues at the Roslin Institute in Edinburgh,Scotland. They cloned successfully a sheep named Dolly . Dolly wasborn on 5th July 1996 and was the first mammal to be cloned.(a) Finn Dorsett sheep (b) Scottish blackface ewe (c) DollyDuring the process of cloning Dolly, a cell was collected from the mammary glandof a female Finn Dorsett sheep [Fig. 9.13 (a)]. Simultaneously, an egg was obtainedfrom a Scottish blackface ewe [Fig. 9.13 (b)]. The nucleus was removed from theegg.

Normalsexual means. Unfortunately, Dolly died on 14th February 2003 due to a certainlung disease.Since Dolly, several attempts have been made to produce cloned mammals.However, many die before birth or die soon after birth. The cloned animals are many –a -time found to be born with severe abnormalities

(a) Finn Dorsett sheepb) Scottish blackface ewe (c) Dolly

We Have learn from these Presentation There are two modes by which animalsreproduce. These are: (i) Sexual reproduction,and (ii) Asexual reproduction. Reproduction resulting from the fusion of maleand female gametes is called sexualreproduction. The reproductive organs in the female includeovaries, oviducts and uterus. The reproductive organs in male includetestes, sperm ducts and penis. The ovary produces female gametes called ovaand the testes produce male gametes calledsperms. The fusion of ovum and sperm is calledfertilization. The fertilized egg is called a zygote.

Fertilization that takes place inside the femalebody is called internal fertilization. This isobserved in human beings and other animalssuch as hens, cows and dogs. Fertilization that takes place outside the femalebody is called external fertilization. This isobserved in frogs, fish, starfish, etc. The zygote divides repeatedly to give rise to anembryo. The embryo gets embedded in the wall of theuterus for further development. The stage of the embryo in which all the bodyparts are identifiable is called foetus. Animals such as human beings, cows anddogs which give birth to young ones are calledviviparous animals.

Animals such as hen, frog, lizard and butterfly which lay eggs are called oviparous animals. The transformation of the larva into adult through drastic changes is calledmetamorphosis. The type of reproduction in which only a singleparent is involved is called asexualreproduction. In hydra, new individuals develop from buds.This method of asexual reproduction is calledbudding. Amoeba reproduces by dividing itself into two.This type of asexual reproduction is calledbinary fission.

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