i want to know the mechanism of reproduction.?

Answer 1

Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring. It is characterized by two processes: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the restoration of the original number of chromosomes. During meiosis, the chromosomes of each pair usually cross over to achieve genetic recombination.

The evolution of sex is a major puzzle in modern evolutionary biology. The first fossilized evidence of sexually reproducing organisms is from eukaryotes of the Stenian period, about 1.2 to 1 billion years ago with DNA forming 3.5 - 4.6 billion years.[1]Sexual reproduction is the primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants. Bacterial conjugation, the transfer of DNA between two bacteria, is often mistakenly confused with sexual reproduction, because the mechanics are similar.

A major question is why sexual reproduction persists when parthenogenesis appears in some ways to be a superior form of reproduction. Contemporary evolutionary thought proposes some explanations. It may be due to selection pressure on the clade itself—the ability for a population to radiate more rapidly due to a changing environment through sexual recombination than parthenogenesis allows. Alternatively, sexual reproduction may allow for the 'ratcheting' of evolutionary speed as one clade competes with another for a limited resource.


In the first stage of sexual reproduction, 'meiosis', the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). During 'fertilization', haploid gametes come together to form a diploid zygote and the original number of chromosomes (2n) is restored.

Answer 2

Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring. It is characterized by two processes: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the restoration of the original number of chromosomes. During meiosis, the chromosomes of each pair usually cross over to achieve genetic recombination.

The evolution of sex is a major puzzle in modern evolutionary biology. The first fossilized evidence of sexually reproducing organisms is from eukaryotes of the Stenian period, about 1.2 to 1 billion years ago with DNA forming 3.5 - 4.6 billion years.[1]Sexual reproduction is the primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants. Bacterial conjugation, the transfer of DNA between two bacteria, is often mistakenly confused with sexual reproduction, because the mechanics are similar.

A major question is why sexual reproduction persists when parthenogenesis appears in some ways to be a superior form of reproduction. Contemporary evolutionary thought proposes some explanations. It may be due to selection pressure on the clade itself—the ability for a population to radiate more rapidly due to a changing environment through sexual recombination than parthenogenesis allows. Alternatively, sexual reproduction may allow for the 'ratcheting' of evolutionary speed as one clade competes with another for a limited resource.


In the first stage of sexual reproduction, 'meiosis', the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). During 'fertilization', haploid gametes come together to form a diploid zygote and the original number of chromosomes (2n) is restored.

Answer 3

sexual eproduction:-
A number of single-celled organisms multiply by conjugation. In this process, which is analogous to fertilization, two similar unicellular organisms fuse, exchange nuclear materials, and then break apart. Each organism then reproduces by fission; occasionally, after conjugation, the participating organisms do not reproduce, the process in these instances seeming merely to revitalize the organisms. Conjugation is the most primitive method of sexual reproduction by which organisms having genetic characteristics derived from two parents are produced. Most multicellular animals and plants undergo a more complex form of sexual reproduction in which especially differentiated male and female reproductive cells (gametes) unite to form a single cell, known as a zygote, which later undergoes successive divisions to form a new organism. The terms fecundation and fertilization are applied to the union of the male and female cells. In this form of sexual reproduction, half the genes, the carriers of inheritable characteristics, in the zygote come from one parent and half from the other parent.

Two Human Sperm Cells The small capsule-shaped head of the sperm cell contains the chromosome contribution from the male. The whiplike tail helps to propel the sperm cell towards the egg, where fertilization takes place.Oxford Scientific Films

Many lower multicellular organisms and all higher plants undergo an alternation of generations. In this process, a sexually produced generation alternates with an asexually produced generation. In some organisms that reproduce sexually, a process known as parthenogenesis occurs in which the female sex cell develops without fertilization.

In higher animals, individuals of a single species are either male or female, according to whether they produce male reproductive cells or female reproductive cells. The typical male reproductive cell, which is known as a sperm, spermatozoon, or spermatozoan, is a motile cell with a head containing the nucleus and a whip-like tail with which it swims. The typical female reproductive cell, which is known as an egg or ovum, is a rounded cell many times larger than the sperm and containing large amounts of cytoplasm surrounding the nucleus. Plant reproductive cells are roughly similar to animal cells, the male cell being known as the sperm or microgamete and the female cell as the ovum or macrogamete.

Answer 4

Mechanism of reproduction is species - specific.Because actual reproduction takes place by the maintenance of complete diploidy of a species either by asexual or sexual reproduction. Asexually, as in the case of Amoeba, tetraploidy (4n) is attained prior to binary fission and is retained to each of the daughter amoebae as diploidy (2n). Sexually, as in the case of Homo sapiens, the same tetraploidy is attained prior to mitoses I and II but is retained to each and every daughter cell (ovum or sperm) as haploidy (n). The metabolically required diploidy is attained only thro' gametic fusion during fertilization. The latest discovery as CYCLINS play an important role in each and every species' maintenance of diploidy.

Answer 5

first know mechanisum of production then reproduction..