Reproduction in Organism

Reproduction in Organism

Reproduction in Organism: Reproduction is the biological process in which organisms produce their type of offspring. Reproduction is an important part of the life cycle possessed by an organism. In other words, reproduction is a biological process wherein younger ones produced are identical to their parents. This phenomenon is significant in the continuity of the species, generation after generation. This process is necessary to maintain the continuity of species on the earth. Reproduction also helps in increasing the population and as a result, sustains a balance in the ecosystem amongst different biotic components precisely. Without reproduction, the life that is thriving now would cease. Reproduction also facilitates evolution due to variations arising from the process of reproduction through the intermingling of species.

There are two modes of Reproduction depending upon the participation of one or both parents:

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Reproduction in Organism: a) Asexual Reproduction b) Sexual Reproduction

Fig:- Reproduction process in tortoise

Fig:- Reproduction process in Frog

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Asexual Reproduction

The mode of reproduction in which a single organism is capable to produce its own type of offspring is known as asexual reproduction.

Characters of asexual reproduction in Organism

• Single parent involved.
• No need for gametes.
• Fertilization doesn’t take place.
• No variation in offspring.
• Offspring are morphologically and genetically identical.

Types of Asexual Reproduction

• Binary Fission:- It is a simple and common method of asexual reproduction. In this method, a single-cell organism is divided into two daughter cells. Then each cell grows into a new individual. In binary fission first nucleus divides then the cell divides. Example – Amoeba, Paramoecium, Euglena, etc.
• Multiple Fission:- In a single-celled organism, the nucleus divides into many nuclei and form many daughter cells which further grows into new individuals, then known as multiple Fission. Example – Plasmodium, etc.
• Budding:- An outgrowth develops on the parent body. This outgrowth is known as bud. When bud matures then gets separated from the parent body and develops into new individuals. Example – Yeast, Hydra, etc.
• Fragmentation:- In multicellular filamentous organisms, the body breaks into fragments, and each fragment grows further into new individuals. Example – Spirogyra, etc.
• Regeneration:- In some organisms body breaks into segments. After some time each segment forms/develops the rest part and changes itself into new individuals. This refers to regeneration. Example – Planaria, Starfish, etc.
• By spore formation:- Spores are small and round part reproductive structures. They are found in sporangium. When sporangium matures then it ruptures and liberates spores outside. When favorable conditions are available then spore germinates into new individuals. Example – Algae, Fungi, etc.
• Vegetative reproduction/vegetative propagation:- When new plants develop from root, stem, or leaf it is known as vegetative reproduction. Examples of vegetative propagation –

1. By root: eg- Sweet potato, Dahlia
2. By stem:-
3. Runner:- eg- dube grass, oxalic, etc.
4. Rhizome:- eg- turmeric, ginger, banana, etc.

c. Tuber:- eg- Potato, etc.

1. Corm:- eg- Elephant foot yam, etc.
2. Stolon:- eg- Jasmine, etc.
3. Sucker:- eg- Rose, etc.

d. Offset:- eg- Water hyacinth(also known as the terror of Bengal), etc.

By leaf:- eg- Bryophyllum, Begonia, etc.

Sexual Reproduction

The mode of reproduction in which two individuals are involved to produce young ones is known as sexual reproduction.

Characters of sexual reproduction

• Two parents are involved.
• Need of gametes (sperms and ovum).
• Fertilization takes place.
• Variation occurs in young ones.
• Variation helps in evolution.

Phases of sexual reproduction

• Vegetative phase:- The growth period of a plant is called the vegetative phase.
• Juvenile phase:- The growth period of an animal is called the juvenile phase.
• Reproductive phase:- The reproductive period of an organism is known as the reproductive phase. It starts at the end of the growth period of the organism.

Senescent phase:- The old period of the organism is known as the senescent phase.

Reproduction In Plants

• The appearance of flowers refers to the reproductive phase.
• In monocarpic plants, the fruit develops only once in the whole life cycle. Ex:- Wheat, Banana, Bamboo, etc.
• In polycarpic plants, fruits come many times in life. Ex:- Mango, Litchi, Guava, etc.
• In bamboo species, flowers appear only once after 50 to 100 years.
• A plant, Strobilanthus kuthiyana (commonly known as Neela Karanji), flowers appear once after 12 years. This plant is found in Kerela, Tamil Nadu, Karnataka, etc.
• In the reproductive phase, morphological and physiological changes in the body occur.
• In females, the start of the oestrus cycle(menstrual cycle) indicates the reproductive phase.
• In non-primate mammals(eg – rats, cats, dogs, sheep, etc) cyclic changes occur during the reproductive phase is known as the ‘Oestrus Cycle’. It is also known as the heat period.
• In primate mammals(eg – Monkeys, apes, and humans) cyclic changes occur during the reproductive phase known as the ‘Menstrual Cycle’. In this cycle, vaginal bleeding occurs every month in females until the egg fertilizes.
• The animals whose reproduction is active in a particular season are then known as seasonal breeders. Eg. Dogs, etc.
• The animals whose reproduction is active throughout the years are known as continuous breeders. Eg. Human, Cow, etc.

Sexual Reproduction In Human

Reproduction in human beings involves the fusion of male and female gametes produced in their reproductive system. The male reproductive system is different from the female reproductive system, both in structure and in function. Human reproduction consists of the following steps:-

1. Gametogenesis
2. Insemination

III. Fertilization

1. Implantation
2. Gestation
3. Parturition

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Events of Sexual Reproduction

1. Pre-fertilization:- The event before fertilization. It includes gametogenesis and the transfer of gametes.
2. Fertilization:- The process of fusion of male gamete(sperm) with the female gamete(ovum or egg) is called fertilization. After fertilization, a diploid zygote is formed.
3. Fertilization is also known as SYNGAMY.

Post-fertilization:- The event after fertilization is called post-fertilization. It includes zygote development and embryogenesis.

Reproduction in Organism - Question with Answers

Question. Difference between Asexual and sexual reproduction?

Answer: Sexual Reproduction:- In this mode of reproduction, a new offspring is produced by the participation of two parents of the opposite sex. This type of reproduction is seen in all multicellular organisms including birds, reptiles, dogs, cats, cattle, elephants, etc. The complete process of sexual reproduction consists of a set of events, including:

• Pre-fertilization
• Fertilization
• Post-fertilization

Asexual Reproduction:- In this mode of reproduction, a new offspring is produced by the involvement or participation of single parents only. The produced offsprings are not only identical but are also the exact copies of their parent because in this process a single parent divides itself to reproduce its offspring.

Question. What is the importance of vegetative reproduction or vegetative propagation?

Answer: The importance of vegetative reproduction is followed below:-

• Flowers and fruits develop early.
• No need for seed and fruit for the formation of new plants.
• Disease-free plants obtained.
• It is helpful in micropropagation (grows thousands of plants at a time).
• It is generally used in horticulture(grows flowering plants).

Question. The period from birth to natural death is called _______________?

a. Vegetative phase

b. Life span

c. Reproductive phase

d. Binary fission.

Answer:Correct answer is option b.

a. Vegetative phase:- The growth period of a plant is called the vegetative phase.

b. Life span:- The period from birth to natural death of an organism is called its life span. Different species have different periods. Eg. Crow- 15years, Elephants- 80years, Tortoise- 100-150years, etc.

c. Reproductive phase:- The reproductive period of an organism is known as the reproductive phase. It starts at the end of the growth period of the organism.

d. Binary fission:- It is a simple and common method of asexual reproduction. In this method, a single-cell organism is divided into two daughter cells. Then each cell grows into a new individual. In binary fission first nucleus divides then the cell divides. Example:- Amoeba, Paramoecium, Euglena, etc.