How Do Organisms Reproduce ?

This post provides you a general and basic facts related to reproduction. Enjoy reading......!

Reproduction

 Biological process by which a living organism produces an offspring similar to itself is called Reproduction.

 In this process, Genetic Information transferred from the parents to the offspring in the form of DNA

 DNA (Deoxyribonucleic acid) - It is a genetic material found in chromosomes present in the nucleus of a cell

 Reproduction may be classified into Two groups or types: - Asexual and Sexual reproduction.

Asexual reproduction

It Does not involve the fusion of gametes

 It Requires only one parent

 Offspring’s produced are exact copies of their parents.  They are called Clones.

 Modes of asexual reproduction : Asexual reproduction is of the following types:

1. Fission-  The type of reproduction in which parent organisms divide into 2 or more than 2 parts and each part gives rise to new daughter organisms is called fission. It involves cell division or splitting of cells.

o It is of two types:

Binary fission : The type of asexual reproduction in which parent organisms divide into 2 parts and each part gives rise to new daughter organisms is called binary fission.

1.It may take place along any plane. eg.- amoeba

2. It may take place along single plane eg- Leishmania

3. It may take place along Longitudinal plane e.g., Euglena

Multiple fission: The type of reproduction in which parent organisms divide into more than 2 parts and each part gives rise to new daughter organisms is called fission. It involves cell division or splitting of cells.e.g., Plasmodium

Multiple fission in Plasmodium

multiple fission in Plasmodium 

o Fragmentation- New organisms are formed from fragments of parents. e.g., lichens

o Regeneration- New organisms are formed from body parts. e.g., Planaria

o Budding- New individuals form protrusion called buds. e.g., Hydra, Yeast

o Vegetative propagation- New plants are formed from the vegetative parts such as leaves, roots and stems .e.g., Bryophyllum, potato, ginger etc

Bryophyllum Leaf showing vegetative reproduction

o Spore formation- Large number of spores produced in sporangia. e.g., Rhizopus

spore formation in Rhizopus

Sexual reproduction

It  Involves fusion of male and female gametes- male gametes or sperms and female gametes of eggs or ova.

 It Requires two parents- male and female

 It Allows more variations in offsprings

 Sexual reproduction in plants

o Angiosperms- flowering plants belong to Angiosperms. Flower is the modified shoot and the reproductive part of the plants.

o Parts of flowers–  A typical flower consists of four parts: 

1. Calyx  which consists of sepals
2. Corolla which consists of petals
3. Androecium which consists of stamens and 
4. Gynoecium which consists of carpels or pistils.

Stamens: Male reproductive parts of flowers are called stamens. They have 3 parts: anther, connective and filament.

Carpels: Female reproductive parts of flowers and consists of style, stigma, and ovary

o Bisexual flowers: Both stamens and carpels are present e.g., Hibiscus

o Unisexual flowers: Either stamen or carpel is present e.g., corn

o Pollen released from the bursting of anther, which contains male gametes

o Each ovule contains one egg cell or female gamete

o Pollination: transfer of pollens from the anther of one flower to the stigma of the same or different flower

o Fertilization: Process of fusion of male and female gametes

o After fertilization: zygote = embryo, ovule = seed, ovary = fruit

 Sexual reproduction in animals

o Puberty: A period of physical change by which a child’s body becomes an adult’s body and capable of reproduction

o Secondary sex characteristics: The body changes during puberty

o Male reproductive organs: Pair of testes, vas deferens, prostate gland, seminal vesicles

o Testes: Produce sperms and hormone testosterone

o Sperms: Contain male gametes

o Female reproductive organs: Pair of ovaries, pair of oviducts, uterus, and vagina

o Ovaries contain thousands of eggs

o Sperms enter the female body through the vagina

o Fertilization: The process of fusion of the nucleus of the sperm with the ovum to form a zygote

o Zygote divides to form an embryo

o Embryo implanted in the uterus

o Foetus develops inside the mother’s body for nine months

o Menstruation: If the egg is not fertilized, then the uterus lining breaks down and is released in the form of blood and mucous through the vagina

o Sexually transmitted diseases: Infections that get transferred through sexual contact e.g., herpes, HIV-AIDS, syphilis, gonorrhea etc.

o Contraceptive methods help avoid pregnancy: These include natural methods, barrier methods, oral contraceptives, implants, and surgical methods

                                       

BEST OF LUCK