LESSON: REPRODUTION IN ANMALS

SCIENCE

DONE BY : R.MANSHI8-A

CONENTS

Sexual ReproductionMale ReproductiveFemale ReproductiveFertilisationExternal and Internal fertilisationTest-tube babyReproductive system of male and female frogMetamorphosisAsexual ReproductionBinary fissionBuddingViviparous and oviparous AnimalsDolly the clone

Sexual Reproduction: The reproduction in which the both male reproductive organs and female reproductive organs involved to give birth to new individual is called sexual reproduction.

Like plants, the the reproductive parts in animals also gametes that fuse to form a zygote. It is the zygote which develops into a new individual.

SEXUAL RERODUCTION

MALE REPRODUCTIVE ORGANS IN HUMANS

MALE REPRODUCTIVE ORGANGS

The male reproductive organs include a pair of testes, two sperms ducts and a penis. The testes produce male gametes called sperms.

Millions of sperms are produced by the testes.

FEMALE REPRODUCTIVE ORGANS IN HUMANS

[OVIDUCTS]

FEMALE REPRODUCTIVE ORGANS

The female reproductive organs are of ovaries, oviducts[fallopian tubes] and the uterus. The

ovary produces female gametes called ova[eggs]. A single matured egg is released into oviduct by

on of the ovaries every month. Uterus is the development of the baby takes place. Like the

sperm, an egg is also a single cell.

An ovum (plural ova, ovum meaning egg or egg cell) is a haploid female reproductive cell or gamete. Both animals and

embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after

fertilization.

HUMAN OVUM

Sperm were first observed in 1677 by Antonie van Leeuwenhoek using a microscope. The

sperms are produced by testes. Though sperms are very small in size, each has head, a middle

piece and a tail. Each sperm is a single cell with all usual cell components.

SPERM

PARTS OF SPERM A HUMAN SPERM

SPERM FERTILIZING A FEMALE EGG

The first step in process of reproduction is the fusion of a sperm and an ovum. When sperms come in contact with an egg, one of the sperms may fuse the egg. Such fusion of the

egg and the sperm is called Fertilisation

FERTILISATION

A VIDEO ON FRETILISATION

Fertilization involves the fusion of the male and the female gamete. The male and the female gametes are released from the male and the female reproductive organs.

Sperms or male gametes are released from the male reproductive organ i.e., the penis. These sperms then enter the female body through the vagina. Then, they travel

through the fallopian tubes where they meet the eggs. Hence, the process of fertilization takes place in the fallopian tubes.

During fertilization, the haploid nucleus of the sperm and that of the ovum fuse with each other to form the zygote. This zygote divides to form an embryo which in turn develops into a foetus.

PROCESS OF FERTILISATION IN HUMAN BEINGS

INTERNAL FERTILISATION AND EXTERNAL FERTILISATION

The fertilisation which takes place inside the female body is called Internal fertilisation.

Fertilisation in which the fusion of male and female gamete takes outside the body is called

External fertilisation. Example: frog, fish, starfish etc.

A zygote is always synthesized from the union of two gametes, and constitutes the first stage in a unique organism's development. Zygotes are

usually produced by a fertilization event between two haploid cells—an ovum (female gamete) and a sperm cell (male gamete)—which combine to

form the single diploid cell. Such zygotes contain DNA derived from both the parents, and this provides all the genetic information necessary to form a

new individual.

ZYGOTE

Fusing nuclei

FORMATION OF ZYGOTE

DEVOELOPMENT OF ZYGOTE

TEST-TUBE BABYIn some women oviducts are blocked. These women are unable

to bear babies because sperms cannot reach the egg for fertilisation. In such cases, doctors collect freshly released egg and sperms and keep them together for a few hours for IVF. In case fertilisation occurs, the zygote is allowed to develop for

about a week and then it is placed in the mother’s uterus. Complete development takes place in the uterus and the baby is born like other babies. Babies born through this technique are

called test-tube baby

In vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside the womb, in vitro.

EMBRYO

Fertilisation results in the formation of zygote which begins to develop into embryo. The zygote divides repeatedly to give rise to a balls of cells. The cells

then begin to form groups that develop into different tissues and organs of body. This

developing structure is termed an embryo. The embryo gets embedded in the walls of uterus for

development.

FOETUS

The stage embryo in which all body parts can been seen is called Foetus.

UTERUS

Foetus in the uterus

Reproductive system of male and female frog

A female frog sitting on a mass of its own spawn [eggs]

REPRODUCTION IN FROGSDuring spring or rainy season, frogs and toads move to ponds and

slow flowing streams. When the male and female come together in water, the female lays hundreds of eggs. A layer of jelly holds the

eggs together and provides protection to the eggs. As the eggs are laid, the male deposits sperms over them. Each sperm swims

randomly in water with the help of its long tail. The sperms contact with the eggs this results in fertilisation.

Though the animals lay hundreds of eggs and release millions of sperms, all the eggs do not get fertilised ,this is because the eggs

get exposed in water movement, wind and rainfall. Also, there are other animals in pond which may feed on eggs

Metamorphosis is a biological process of transforming a larva into an adult. This involves

relatively sudden and abrupt changes in the animal’s structure. Frogs and insects are

examples of organisms showing metamorphosis.

METAMORPHOSIS

ASEXUAL PRODUCTION

Asexual reproduction is a mode of reproduction that does not involve

the fusion of the male and the female gamete. It requires only one parent, and the offsprings

produced are exact copies of their parents.

It is a type of asexual reproduction in which a single cell divides into two halves. Organisms that reproduce through binary

fission are bacteria and Amoeba. In Amoeba, the division of cells can take place in any plane. It involves the division of its nucleus into two nuclei, which is followed by the division of its body into

two halves. Each half of the body receives a nucleus.

BINARY FISSON IN AMOEBA

DIVIDING NULEUS DAUGHTER AMOEBAE

BINARY FISSON

Budding involves the formation of a new individual from the bulges, known as buds formed on the parent body. This method of

reproduction is common in Hydra. In Hydra, the cells divide rapidly at a specific site and develop as an outgrowth, called the bud. These buds,

while being attached to the parent plant, develop into smaller individuals. When these individuals become mature enough, they

detach from the parent’s body and become independent individuals.

Budding in Hydra

BUDDING

Animals which lay eggs outside their bodies are known as oviparous animals. All birds, frogs, lizards, crocodiles etc.

belong to this group.

Animals which give birth to young ones are known as viviparous animals. Animals like lions, tigers, dogs, and

humans belong to this group.

OVIPAROUS ANIMALS AND VIVIPAROUS ANIMALS

Dolly was the first cloned mammal, and is genetically identical to its parent sheep.

Cloning is creating an exact copy of a biological entity. A clone is created by inserting the complete genetic material of a regular body cell from

a donor into a recipient. Sheep are viviparous animals, and so propagate their offspring sexually. Sir Ian Wilmut from Roslin

Institute in Edinburgh, Scotland created Dolly.

DOLLY, THE CLONE

WORLD’S FIRST CLONED BUFFALO WAS IN INDIA!

Scientists at India’s National Dairy Research Institute, in the Indian state of Haryana, produced

the first cloned buffalo back in February 6 2008, using DNA from the ear of an adult female—though

unfortunately, it died of pneumonia soon after its birth.

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