PITE Services: Reproduction (How do Organisms Reproduce)

How does Organisms Reproduce?

Introduction:

Reproduction is a process in which new individual of the same species are produced by an existing organism. In simple terms, reproduction is a biological process in which organism produces their young ones to continue the race.

Types of reproduction
or
Modes of reproduction

Reproduction is basically of two types:-

1. Asexual reproduction.

2. Sexual reproduction.

Asexual reproduction:- It is a type of reproduction in which single parent cell is involved. The new individual is formed from the single parent cell. There is no need of special reproductive organs for this type of reproduction. It can be usually seen in lower organisms.

For eg:- Binary fission in Amoeba,

Budding in Hydra.

Types of Asexual reproduction: .

a) Fission:- The type of asexual reproduction in which a single parent cell divides into two or more individuals is called as fission.

For eg:- Amoeba, plasmodium etc.

It is of further two types

1. Binary fission:- The type of asexual reproduction in which single parents cell divides into two daughter cell is called as binary fission,

Eg:- Amoeba, paramecium { Animal species}, Bacteria, Yeast etc {plant speices}.

Binary Fission in Ameoba

Binary Fission in Yeast

2 Multiple fission:- It is a type of asexual reproduction in which single parent cell divides into more than two daughter cells.

Eg:- Plasmodium

Multiple Fission in Plasmodium

Explanation of Binary fission in Amoeba.

Amoeba is a unicellular organism which reproduces through Binary fission; during the process, the nucleus first divides a mitotic ally into two followed by the division of cytoplasm. Finally the parent cell splits into two daughter cells as shown below.

b) Fragmentation:- This type of reproduction is commonly seen in multicellular organism which have simple body structure. In this process, parent organism divides into two or more fragments. Under favourable conditions these fragments grow into new independent individual.

Eg:- Spirogyra, flatworms etc.

Fragmentation in Spirogyra

c) Regeneration:- It is a type of asexual reproduction in which an organism ha ability to regenerate its lost parts of body which have been removed as by an injury or auto- assumption of body parts.

Eg:- planaria, some species of hydra.

d) Budding:- It is a method of asexual reproduction in which new individual develops from a small our growth on the surface of the parent individual. This method of reproduction is commonly found in hydra, Yeast, sponges etc

Budding in HYDRA

Explanation of Budding in Hydra:- During budding in the Hydra, a small bud like out growth ( called as bud) arise at one end of the parent hydra. This bud gradually enlarges in size due to repeated cell division. After attaining the maturity, the bud death aches itself from parent body and develops into new independent individual.

e) Spore formation:- Spores are reproductive structures which have ability to give rise to a new individual. Thus “spore formation is a type of asexual reproduction in which spores give rise to the new individual directly or indirectly”

eg:- Rhizopus, Mucor, penicillum etc.

f) Vegetative propagation:-

It is the type of asexual reproduction by which new plants develop from the vegetative parts (like stem, roots, leaves etc.) of the plant. It is very beneficial in those plants which does into produce seeds. It is two types.

1) Natural vegetative propagation:- Natural vegetative propagation takes place by leaves (e.g in Bryophyllum) by roots (e.g in Dahlia, sweet potato) by stem (e.g in onion, potato rhizome etc)

2. Artificial vegetative propagation:

2) Artificial vegetative propagation:-some of the important common methods of artificial vegetative propagation are.

1) Cutting:- In this method small pieces of stem cutting are used to get the new plant. These cutting are placed vertically in the soil. The roots develop from the under-ground part of the stem.

Eg:-In pine apple, sugarcane rose etc.

Cutting of Rose stem

2) Layering:- In layering, the roots are artificially induced on the stem branches before they are detaches from the parent plant for propagation.

Layering

Layering is done by two common methods:

a)layering and

b) Air layering

a) Mound layering:- In this method, a lower flexible branch of stem is pulled and a portion of it is buried in the soil in such a way that the growing tip remains above the soil surface and the branch remains attached to the parent plant. Eg :- raspberry, strawberry

b) Air layering: - In this method, a notch of 2-3cm wide is of an aerial etc. Eg:-lemon, guava etc.

3) Grafting: - Grafting is a method in which parts of two plants are joined in such a way that they grow as one plant. The rooted is called the stock. The portion of other plant (bud, branch, etc) that is grafted on the stock is called scion. Eg Orange, lemon etc.

Grafting (Stock and scion)

g) Micro-propagation (tissue culture):- In this type of reproduction, the plant cells or tissues are cultured in sterilized medium containing necessary nutrients and hormones. The technique results in the formation of in differentiated mass of cells called as callus. Eg:- In case of orchit, Dahlia etc.

Tissue Culture

h) Parthenogenesis’:- It is the method of developing new organism from unfertilized egg. The new organism may be haploid or diploid depending upon the egg being used for the process.

Sexual reproduction:

-It is a type of reproduction in which two parents are required, the male gamete (sperm) and the female gamete (ovum) give rise to the new off- springs.

Fertilization:-

It is the process in which male gamete (sperm) and female gamete (ovum) fuse together to form zygote. The zygote is considered as a beginning of a new individual a beginning of a new individual fertilization is of two types.

1) Internal fertilization:-

It is a type of fertilization in which the fusion of gametes takes place

inside the female body. In other words in this type of fertilization,

formation of zygote takes place inside the female body.

eg:- Human beings, cats, hens etc.

2) External fertilization: - It is a type of fertilization in which the fusion of gametes takes place outside the female body. In other words in this type of fertilization, formation of zygote takes place outside the female body. Eg:- frog, fishes etc.

Fertilization in human beings

Reproduction process in human beings.

Human being reproduce sexually i.e, they need two parent cells to reproduce. They type of fertilization is internal in human beings. The process is explained as: Internal fertilization in human beings is achieved by the process of copulation. During copulation human male inserts his penis into vagina of the female and releases his gamete (sperm) inside the genital tract. This is called as ejaculation. The sperm are highly active and mobile thus they travel upwards towards Fallopian tube within five minutes. Finally one of the sperm fertilizes the ovum in fallopian tube. The fusion of male gamete (sperm) and female gamete (ovum) results in the formation of zygote and the process is called fertilization. Fertilization is possible only when copulation occurs during ovulation period. Zygote is considered as the beginning of pregnancy.

Post fertilization changes

When male and female gametes has fuse together to form zygote, it is called as “conception.” Immediately after conception, the zygote moves from Fallopian tube towards the uterus and start dividing by nuclear and cell divisions. This process is called as cleavage. The zygote gets embedded in the thick inner lining of the nucleus. This process takes place about seven days after fertilization. At this stage, a special tissue called as “placenta” develops between uterine wall and the embryo results in the formation of fetus. At this stage, various body parts of the individual (baby) can be identified. These changes can be seen after nine weeks. The time period from the complete development of fetus ( i.e., from conception till birth)is called as gestation.

The development of child inside the Mother’s body takes approximately nine months. After nine months a mother gives birth to a baby. “The art of giving birth the end of gestation is called as parturition””.

Puberty:-

The stage at which the sexual maturity is attained by the individuals is called as puberty. At this stages, reproductive organs become functional in human males and females. It is attained at the stages of 11- 12 years in the girls and the age of 13-14 years in boys.

Changes in boys at puberty:

·         Start of puberty. Between 9 ½ and 14 years old.
·         First puberty change . Enlargement of the testicles.
·         Penis enlargement. Begins about 1 year after the testicles begin enlarging.
·         Pubic hair appears. About 13 ½ years old.
·         Wet dreams (nocturnal emissions). About 14 years old.
·         Hair under the arms and on the face, voice change, and acne. About 15 years old.

Changes in Girls at Puberty
·         Start of puberty. Between 8 and 13 years old.
·         First puberty change. Breast development.
·         Pubic hair appears. Shortly after breast development.
·         Hair under the arms. About 12 years old.
·         Menstrual periods. Between 10 and 16 ½ years old.

Male reproductive system
The male reproductive system includes testes, scrotum, spermatic ducts, sex glands, and penis. All these organs work together to produce sperms, male gamete, and other components of semen.

Penis
It involves three cylindrical spaces of erectile tissue. The two which are larger, the corpora cavernosa lie side by side and the third one is sinus, The penis becomes rigid when these spaces are filled by the blood. It is inserted into the vagina during Copulation.
Scrotum
It is a sac of thick skin that protects and surrounds the testes. It also controls the temperature of the testes since they have to be at a slightly lower temperature than the body temperature for suitable sperm creation.
Testes
They are the oval bodies, around 1.5 to 3 inches in length. Generally, the left testis hangs slightly lower than the right one.
The two primary functions of tests are as follows:
- Producing testosterone – a male sex hormone.
- Producing sperms -a carrier of man’s genes.
Seminal Vesicles & prostate generate:
The seminal vesicles fluid nourishes the sperm. This fluid provides a maximum volume of the semen, wherein the sperm is ejected during ejaculation.
Urethra
It is a tube-like structure that connects the urinary bladder to the urinary meatus. This region is included in the urinary tract that takes urine from the bladder where semen is ejaculated.
or

Female Reproductive System Anatomy
The female reproductive system is framed to perform different functions. The female reproductive system is composed of a pair of ovaries along with oviducts, vagina, cervix, uterus, and the external genitalia that are located in the pelvic region. These parts along with a pair of mammary glands that are integrated both functionally and structurally also support the process of ovulation, fertilization, birth and finally the child care.
Ovaries
Ovaries act as the main female sex organs that produce the female gamete and various hormones. These organs are situated one on both the side of the lower abdomen
Uterus
A uterus is also called the womb. It is a muscular, inverted pear-shaped organ of the female reproductive system. The cervical canal along with the vagina creates the birth canal. The vagina is a muscular tube which starts at the lower end of the uterus to the outside.
Fallopian Tubes
Fallopian tubes are a pair of muscular tubes and funnel-shaped structures, extend from the right and left of the superior corners of the uterus to the edge of the ovaries. Each fallopian tube is covered by cilia that functions by carrying the ovum to the uterus.
Vagina

The vagina is a muscular and elastic tube that connects the cervix to the external body. Its main function is to receive the male penis in sexual intercourse and delivers sperm to the fallopian tubes and uterus. It also acts as a birth canal by expanding to allow delivery of the fetus during childbirth.