Sexual and Asexual Reproduction

In our environment, Organisms cannot live forever and that is why the continuity of the species relies on individuals reproducing. There are two types of reproduction in our environment; one is asexual reproduction and another one is sexual reproduction. There are so many unicellular Organisms such as protists and bacteria as well as some plants and some animals also reproduce asexually. Those Organisms that reproduce asexually are found in stable environments to which they are very well suited. Most of the multicellular Organisms usually reproduce sexually. In sexual reproduction, it involves male and female gametes (sperms and eggs) to form a zygote.


Asexual Reproduction 

In asexual reproduction, organisms reproduce by mitotic divisions producing offspring that are identical to their parents- clones.

In multicellular Organisms, an ordinary body cell undergoes cellular division and as a result, a new individual will arise.


Types of Asexual Reproduction In Animals

There are several ways by which Organisms may reproduce asexually 

Fission Reproduction

  • In fission reproduction, a single cell is divided into two equal halves.

  • Fission is one of the common ways of asexual reproduction among unicellular Organisms such as bacteria. 

  • After the mitotic division of the nucleus, fission occurs in which a new organism is formed by splitting the parent cell into two equally sized daughter cells. 

  • It occurs when the environmental conditions are good, such as plenty of food, the right temperature, water, etc. Fission is a very effective way of producing many offspring. Example - Amoeba, Euglena 

(Image to be added soon)


Asexual Budding 

  • Except for the division of cytoplasm which is not equal, Budding is a little bit similar to fission.

  • The new individuals arise from a bud or an outgrown from the parent.

  • In some small multicellular animals, this type of asexual reproduction is observed.

Example - In yeasts, the cell does not divide equally into two halves; instead, there is a large parental cell and a smaller daughter cell.


Budding of Hydra

Many hydrae reproduce asexually by producing buds in the body wall. Budding in hydra occurs when they are well-fed which results in a new bud or sub bud formation. 

On a specific side, due to the repeated cell division leads to the development of bud as an outgrowth. The development of buds occurs when it is fully matured. After maturation, it detaches from the main body and becomes a new independent individual.

(Image to be added soon)


Fragmentation

  • In some multicellular organisms, Fragmentation occurs. In this mode of reproduction, a new organism is formed by each part of the organism which is broken or split into two or more parts. 

  • This fragmentation reproduction is common in marine worms, starfish (echinoderms).


Parthenogenesis

Parthenogenesis is considered as one of the main types of asexual reproduction where the female eggs are developed without fertilization. Pathogenesis is observed to occur naturally in invertebrates, along with some amphibians, fishes, reptiles as well.


Asexual Reproduction In Plants

Fragmentation

There are some green plants that are sophisticated in this asexual reproduction. Offspring may be produced by runners, bulbs, tubers, or rhizomes.


Spore Formation

  • Mostly, Fungi develop the spores. These spores are contained within a structure that is popularly known as sporangium.

  • The spores are formed by the budding. Example - Ferns

(Image to be added soon)


Vegetative Reproduction

  • There are some plants, which are capable of vegetative reproduction. The vegetative reproduction is the system to separate parts of one plant and to form a new independent plant.

  • Vegetative reproduction may arise from many parts of plants including the underground stems and the leaves.

(Image to be added soon)


Parthenogenesis

In some plants, fruits are developed from the ovary without fertilization. This type of fruit is called parthenocarpy and process formation of fruit is called pathogenesis.


Sexual Reproduction

The cells of multicellular organisms are divided into two broad categories, and these are 

  1. Somatic Cells 

Somatic cells are all cells of the body with the exception of the germs cells.

  1. Germ Cells

Germ cells are the cells that give rise to gametes.  The gametes are cells that combine in sexual reproduction to form a new organism.


Process of Sexual Reproduction

  • The process of Sexual Reproduction is mitotic divisions of germ cells that produce haploid gametes (ova and sperm).

  • The sperm and ova meet with each other to form a diploid (two sets of chromosomes) zygote (single cell). 

  • Then zygote divides by mitotic divisions.

(Image to be added soon)


Sexual Reproduction in Animals 

  • The reproductive system is made of the primary and secondary sex organs.

  • In animals, primary sex organs that produce the gametes include ovaries in females and testes in the male.

  • The secondary sex organs contain various glands, ducts, and chambers which provide storage and play important roles in the development of gametes and give protection to the primary sex organ.  

FAQ (Frequently Asked Questions)

1. What are the benefits and disadvantages of sexual and asexual reproduction?

Advantages of Sexual Reproduction

  • Allows species to survive in a different changing environment due to variations. For the survival of the species, it is considered a major benefit. 

  • Produces genetic variations in their younger ones.


Disadvantages of Sexual Reproduction

  • To ensure the gametes are brought together at the right time of the year, the organism may have to change its usual pattern of activity.


Advantages of Asexual Reproduction

  • There is no need to spend energy and time finding a mate.


Disadvantages of Asexual Reproduction

  • These species cannot survive after the environmental change.

2. How can we differentiate asexual reproduction from sexual reproduction?

The main difference between asexual reproduction and sexual reproduction is:

  • In asexual reproduction,  one parent is involved and in sexual reproduction, two parents are involved.

  • Offspring produced in the asexual reproduction are genetically identical to the one parent. While sexual reproduction just means combining genetic material from two parents. 

  • In the most type of asexual reproduction, the original parents disappear while in asexual reproduction original parents remain after the process of reproduction. 

  • In the asexual reproduction genetic variation happens only through random variation whereas, in sexual reproduction, there is more chance for the genetic variation.