Reproduction – Meaning, Types, Types of sexual reproduction, Pollination, Types of pollination

Reproduction - Meaning, Types, Types of sexual reproduction, Pollination, Types of pollination

What is reproduction?

Reproduction is one of the basic characteristics of living organism.The act or process of reproducing, more specifically: the process by which plants and animals give birth to offspring, which fundamentally consists of the segregation of a portion of the parental body by a sexual or asexual process and its subsequent growth and differentiation into a new individual.

What are the types of reproduction?

The two types of reproduction are:

1.Asexual.

2.Sexual.

What is sexual reproduction?

the creation of new living organisms by combining genetic information from two different types of individuals (sexes). Most higher organisms have one sex (male) that produces a small motile gamete that travels to fuse with a larger stationary gamete produced by the other (female).

What is asexual reproduction?

The production of a new organism from a single parent without the involvement of sex cells or gametes is known as asexual reproduction. Asexual reproduction creates a new organism that is identical to the parents.

What is gamets?

Sexual reproduction refers to reproduction that occurs as a result of the fusion of male and female gametes. Male reproductive organs include testes, sperm ducts, and the penis. The ovary produces female gametes known as ova, while the testes produce male gametes known as sperms. Fertilization is the fusion of an egg and sperm.

       The process of sexual reproduction in the most advanced groups of plants-the angeosperms,commonly called flowering plants.

The flower is a plant’s reproductive structure. The flower is a modified part of the shoot system that is used for reproduction. In most cases, the flower emerges from the axil of a leaf or the apex of the stem.

Structure of typical flower

   STRUCTURE OF A TYPICAL FLOWER

The tip of the pedicel has been enlarged to form a disc-shaped thalamus. The different parts of the flower are arranged in four consenteric whorls in the thalamus: calyx, corolla, androicium, and gynoecium.

Calyx refers to the outermost whorls, which are made up of green-colored units known as sepals.

They protect the inner part of the flower while it is in the bud stage.

Corolla is the second from the outside whorl.

It is made up of petals, which are typically brightly coloured units.

The third whorl from the outside is Androecium. It is made up of male reproductive structures known as stamens. Pollen grains containing male gamete are produced by stamens.

The innermost whorl is known as the gynoecium, and it is made up of female reproductive structures known as carpels. Each carpel has a swollen basal ovary, a middle elongated style, and a terminal sensitive region known as the stigma. The ovules, which contain female gamets-ova, are encased in the ovary.

What are the steps in the sexual reproduction process?

  1. Gamate formation and gamate transfer are the two most important processes in sexual reproduction.
  2. Fertilization
  3. Development

1* Gamate Formation:It is the first process to occur during sexual reproduction. Male gamates, as we know, develop in stamens through the formation of pollen grains. Female gamets, on the other hand, develop inside the ovary of carpels.

Meiosis (reduction division) is the process by which a germ cell divides into two fissions, resulting in the formation of four gametes. During fertilisation, male and female gametes fuse to form a diploid (with paired chromosomes) zygote.

1b*Pollination: Pollination occurs once gametes are formed. Pollination refers to the transfer of pollen grains from the anther to the stigma. It occurs through the use of agents such as wind, water, and animals.

It is the process of transferring pollen grains from a flower’s male anther to its female stigma. Every living organism, including plants, strives to produce offspring for the next generation. Plants can produce offspring in a variety of ways, one of which is by producing seeds.

What are the types of pollination?

Pollination occur in two ways:

*Self pollination

*Cross pollination.

Define self pollination?

Self-pollination is the process of transferring pollen grains from the anther to the stigma of the same flower or the stigma of a flower on the same plant. It occurs in plants that are genetically identical.

Define Cross Pollination?

Cross pollination occurs when anthers from a different flower are transferred to the stigma. Flowers can be found on the same plant or on different plants. Cross pollination is common in most plants. Cross pollination requires the assistance of various pollination agents.

What is nectaries?

Plants polluted by insects show certain modification in flowers to attract insects.These modification are mainly concerned with the colour of the petal.Some flowers contain glands called nectaries.

2.Fertilization: It is the second major event during sexual reproduction. This process which follows pollination is called fertilization. It involve the fusion of the haploid male gamate in the pollen grain with the haploid female gamates in the ovules.

To bring about fertilization the pollen grains which get deposited on the stigma of the carpel must penetrate the style and reach the ovule.Hence each pollen grain produces a projection called pollen tube which grows through the length of the style and finally reaches the ovule.The pollen tube enters the ovule and delivers the male gametes. Inside the ovule there is a structure called embroy sac which encloses the female gamate.Then male gamate and female gamete unite.Resulting in the formation of a zygote.This process is called Fertilization.

3.Development: Formation of embryo, seed and fruit.

The third and final event in sexual reproduction is the development of a zygote into a young plant. The various steps are as follows:

*The zygote develops into an embryo, which later differentiates into a seed and grows into a new plant.

 *A nutritive tissue called endoseperm forms around the embryo.

 *The ovules become the seed.

 *The ovule covering transforms into the fruit enclosing the seed.

 *Petals, sepals, and other parts of the plant of the flower fall off.

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