Question

asexual reproduction full information according to ncert book, it's types and example.....
describe breifly​

Answer 1

Answer:

Asexual reproduction

is a type of reproduction which does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from a single cell or from a multicellular organism inherit the genes of that parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many multicellular animals, plants and fungi can also reproduce asexually.[1]

While all prokaryotes reproduce without the formation and fusion of gametes, mechanisms for lateral gene transfer such as conjugation, transformation and transduction can be likened to sexual reproduction in the sense of genetic recombination in meiosis.

Types

Fission

Main article: Fission (biology)

Prokaryotes (Archaea and Bacteria) reproduce asexually through binary fission, in which the parent organism divides in two to produce two genetically identical daughter organisms. Eukaryotes (such as protists and unicellular fungi) may reproduce in a functionally similar manner by mitosis; most of these are also capable of sexual reproduction.

Multiple fission at the cellular level occurs in many protists, e.g. sporozoans and algae. The nucleus of the parent cell divides several times by mitosis, producing several nuclei. The cytoplasm then separates, creating multiple daughter cells.

In apicomplexans, multiple fission, or schizogony appears either as merogony, sporogony or gametogony. Merogony results in merozoites, which are multiple daughter cells, that originate within the same cell membrane,sporogony results in sporozoites, and gametogony results in microgametes.

Answer 2

• Asexual Reproduction Definition

“Asexual reproduction is the mode of reproduction that involved the production of offsprings by a single parent.”

• What is Asexual Reproduction?

Asexual reproduction is a mode of reproduction in which a new offspring is produced by single parent. The new individuals produced are genetically and physically identical to each other, i.e., They are the clones of their parent.

Asexual reproduction is observed in both multicellular and unicellular organisms. This process does not involve any kind of gamete fusion and there won’t be any change in the number of chromosomes either. It will inherit the same genes as the parent, except for some cases where there is a chance of rare mutation to occur.

• Characteristics of Asexual Reproduction

Following are the important features of asexual reproduction:

1.Single parent involved.

2.No fertilization or gamete formation takes place.

3.This process of reproduction occurs in a very short time.

4.The organisms multiply and grow rapidly.

5.The offsprings are genetically similar.

• Types of Asexual Reproduction

There are different types of asexual reproduction:

Binary Fission

Budding

Fragmentation

Vegetative Propagation

Sporogenesis

Types of Asexual Reproduction

1. Binary Fission

The term “fission” means “to divide”. During binary fission, the parent cell divides into two cells. The cell division patterns vary in different organisms, i.e., some are directional while others are non-directional. Amoeba and euglena exhibit binary fission.

It is one of the simplest and uncomplicated methods of asexual reproduction. The parent cell divides into two, each daughter cell carrying a nucleus of its own that is genetically identical to the parent. The cytoplasm also divides leading to two equal-sized daughter cells. The process repeats itself and the daughter cells grow and further divide.

1. Fragmentation

Fragmentation is another mode of asexual reproduction exhibited by organisms such as spirogyra, planaria etc. The parent body divides into several fragments and each fragment develops into a new organism.

Asexual reproduction

1. Regeneration

Regeneration is the power of growing a new organism from the lost body part. For eg., when a lizard loses its tail, a new tail grows. This is because the specialized cells present in the organism can differentiate and grow into a new individual. Organisms like hydra and planaria exhibit regeneration.

Asexual Reproduction

1. Budding

Budding is the process of producing an individual through the buds that develop on the parent body. Hydra is an organism that reproduces by budding. The bud derives nutrition and shelter from the parent organism and detaches once it is fully grown.

Asexual reproduction

1. Vegetative Propagation

Asexual reproduction in plants occurs through their vegetative parts such as leaves, roots, stem, and buds. This is called vegetative propagation. For example, potato tubers, runners/stolon, onion bulbs, etc., all reproduce through vegetative propagation.

1. Spore Formation

Spore formation is another means of asexual reproduction. During unfavourable conditions, the organism develops sac-like structures called sporangium that contain spores. When the conditions are favourable, the sporangium burst opens and spores are released that germinate to give rise to new organisms.

Asexual reproduction

In asexual reproduction, a single cell is divided to produce offspring. The simple cell-by-cell division is not possible in multicellular organisms. Most of the multicellular organisms have a complex body design. They have a higher level of organization like tissues, organs and organ system. Thus, they need a special mode for reproduction.

• Advantages of Asexual Reproduction

Following are the advantages of asexual reproduction:

Mates not required.

The process of reproduction is rapid.

An enormous number of organisms can be produced in a very less time.

Positive genetic influences pass on to successive generations.

It occurs in various environment.

Disadvantages of Asexual Reproduction

The major disadvantages of asexual reproduction are:

Lack of diversity. Since the offsprings are genetically identical to the parent they are more susceptible to same diseases and nutrient deficiencies as the parent. All the negative mutations persist for generations.

Since only one organism is involved, the diversity among the organisms is limited.

They are unable to adapt to the changing environment.

A single change in the environment would eliminate the entire species.

Asexual Reproduction Examples

Following are the examples of asexual reproduction:

Bacteria undergoes binary fission in which the cell divides into two alongwith nucleus.

Blackworms or mudworms reproduce through fragmentation.

Hydras reproduce through budding.

Organisms such as copperheads undergo parthenogenesis.

Sugarcane can be grown through vegetative propagation.