What is Reproduction in Detail

There are two types of Reproduction which are as follows:

  1. Asexual Reproduction
  2. Sexual Reproduction

Asexual Reproductionasexual

In asexual reproduction offspring is produced from body parts other than reproductive organs. It is seen in lower plants and animals. For example: Hydra.

Asexual reproduction is also defined as the type of reproduction in which only a single parent is involved. In asexual reproduction, sex cells (gametes) are not produced. No fusion of gametes takes place for the production of zygote or offsprings. It is only produced from the body parts.

Features of Asexual reproduction

The features of asexual reproduction are as follows –

  1. It is uniparental.
  2. The offspring produced by asexual reproduction is clone of parent. This means that it is exactly a carbon copy of the parent.
  3. It is a fast mode of reproduction.

Different forms of Asexual Reproduction are as follows:

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Binary Fissionbinary fission

Binary Fission is a type of asexual reproduction in which parent cell splits into 2 daughter cells. Binary means two and fission means splitting.  For example: Amoeba.

Amoeba is a single celled organisms that reproduces new individual of its type by dividing its nucleus into two nuclei.

After division of the nucleus, the body of amoeba divides into two parts with each individual part receiving a nucleus.

The two separate bodies of amoeba develop into new individuals.

This method of reproducing new individual by dividing into two individuals is called binary fission.

Steps involved in binary fission are as follows-

  1. The Amoeba first grows in size.
  2. Then its nuclear material doubles.
  3. Constriction appears.
  4. Followed by division of cytoplasm.
  5. Finally two daughter cells (offsprings) are formed.

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Budding

In Budding, a new organism is produced as an outgrowth of the parent
body part. For example: Hydra.

Reproduction in hydra starts by the development of bulges called buds.

The buds are the small outgrowths from a parent hydra that develops into a new hydra.

As the new individual develops from buds the process of reproduction in hydra is called budding.

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Spore Formation 

Spores are small, bulb like structures which develop at the top of the erect hyphae of the fungus plant. These spores are released into the air and germinate. These spores are also released into new individuals after landing into food or soil.

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Fragmentation

It is the accidental process when the broken pieces of an organism (fragments) grows into a complete organism. For example:  Fragmentation in spirogyra.

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Regeneration

When the simple animals like Hydra, Planaria develop a new individual from their broken older part it is known as regeneration. It is carried out by specialized cells which grow large numbers of cells.

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Sexual ReproductionSexual Reproduction

In sexual reproduction, offspring is produced due to involvement of two sexes and that is male and female. No two males or females can produce offspring. Only opposite sexes have capacity to produce offspring.

Reproduction takes place as a result of fusion between two gametes, one from each parent, it is called sexual reproduction.
This process of fusion between two gametes is called fertilization.
The formation of gametes involves exchange of chromosomal (genetic)
fragments between homologous chromosomes causing genetic
recombination which leads to variation.

Features of Sexual reproduction are as follows –gametes

It is biparental

The offspring inherits some characters from parents and some new characters. The process of fusion between two gametes is known as fertilization. For example: If Father has blue eye, sometimes offspring also has blue eyes. This is due to inheritance of characters.

In this process of sexual reproduction, a male and a female gamete (reproductive cells) fuse to form a single cell called Zygote. This zygote gradually develops into an adult, similar to the parents. The individual that grows from a zygote, receives characters of both mother and father.

 

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Reproduction in Human Beings

Sexes:  In this reproduction both sexes are involved and that are Male and female.

Gonads: The reproductive organs of organisms. Both male and female have gonads.

Male gonad

Testis is the male gonad. They produce gametes. Gametes are the cells that are actually participate in fusion process of fertilization. Male gamete is also called sperm.

Female gonad

Ovaries are known as female gonad. Ovaries produces gametes and gametes are known as ovum or egg.

Fertilizationfertilization

It is a fusion of male and female gametes to produce first cell that is called as ZYGOTE.                

Types of Fertilization

  1. External Fertilization
  2. Internal Fertilization

External Fertilization

In this males release sperms and females lay eggs. The fusion of egg and sperm takes place outside the parent’s body. This occurs mostly in aquatic organisms. In this fertilization, all organisms gather in a group. Then, male organisms release their sperms and at the same time female organism release their eggs in water. The fusion of egg and sperm takes place in water and thereby, zygote forms in the water. Hence, offspring is also form in the water. In this process, no parent body in involved.

For example: Larvae stages of frog.

In case of reproduction of frogs, the male and female frogs come together.

Female frogs lay down the eggs. A layer of jelly holds and protects the eggs.

The male frogs deposit the sperms over the eggs laid by the female frog.

The sperm swims in water using its long tail and comes in contact with the eggs.

When the sperms comes in contact with the eggs, they fuse that and lead to the further development of the eggs into a new individual.

This type of fertilisation in which the male and female gametes fuse outside the female body is called external fertilisation.

Internal Fertilization

In this fertilization, male releases sperm in females body. Fertilization occurs inside the female body. When baby is fully formed, then it is delivered out.

The different stages that occur in internal fertilization are as follows:

internal-fertilization

Zygote: It is the first cell formed after fusion.

Embryo: Ball of cells arisen from single celled zygote.

Foetus: In foetus, development of baby occurs after 8 week of fertilization.

Infant: A baby with fully developed organs

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Male Reproductive Systemmale-reproductive-system

Testes: The function of testis is sperm formation. It is facilitated by male sex hormone testosterone.

Scrotum: Scrotum is sac like structure that provides 2 to 3 degree less temperature than body temperature. This 2-3 degree less temperature is  required for sperm formation.

Epididymis:  Epididymis is helpful in storing sperms temporarily.

Vas deferns: It is a duct that carries sperms.

Seminal vesicle: This is a gland that secretes a fluid called seminal fluid. Functions of seminal fluid are as follows:

  1. It provides motility medium to sperms. Motility means ability to move.
  2. It provides nutrition to sperms.

When sperm and seminal fluid fuse, then it is called as semen.

Common duct: It is a duct formed by urethra and vas deferns for the secretion of urine as well as semen.

Structure of Sperm

The secretion of white liquid from male reproductive organ is known as sperm.

It consists of 3 parts which are as follows:structure-of-sperm

  1. Head
  2. Middle piece
  3. Tail
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Fate of Ovum

It includes two processes which are as follows:

  1. To get fertilized
  2. Mensuration

To get fertilized, there is a sequence of events that takes place.

Gamete formation

Formation of egg and sperm occurs in female and male bodies, respectively.

Ovulation

Once the egg is formed it is released from ovary into fallopian tube.

Copulationcopulation

It is an act in which mating of male with female occurs. It this process males sperms enter into females body.

Fertilization

The fusion of sperm and egg to from zygote is fertilization. There are multiple sperms in one secretion, some of them get destroyed and only one sperm is able to fuse with the egg. This process of fertilization occurs in fallopian tube.

Implantation

implantation

It is defined as fixing of Zygote into the uterine wall.

Placenta Formation

It is a temporary formed tissue that provides nutrition to growing embryo. This cord is cut down when the baby is delivered.

Gestation period

gestation-period

The period of development of zygote into fully grown offspring which is ready for delivery. It is 9 months 9 days process.

Parturation

It is the process of expelling fully grown baby from mother’s womb.

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reproduction means giving birth to young ones
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You should go and study chapter 12
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