Reproduction

Introduction

     Reproduction is defined as the production of individuals of the same species, that is the next generation of the species.

Do Organisms Create Exact Copies of Themselves?

     Organisms look similar because their body designs are similar. If body designs are to be similar, the blue prints for these designs should be similar.

Methods of Reproduction

     There are basically two types of reproduction - asexual and sexual. This classification is based on the number of parents.

Asexual Reproduction

     Asexual reproduction is the production of new individuals by mitotic divisions from a single parent.

Asexual Reproduction (Contd...)

     Regeneration of new plants from the vegetative parts of the parent plant is called vegetative propagation or vegetative reproduction. Vegetative propagation is done with the help of vegetative parts such as roots, stem or leaves.

Sexual Reproduction in Plants

     The plants that sexually reproduce have the reproductive structures called the flowers. The flower is a condensed shoot with the nodes present very close to each other.

Advantages and Disadvantages of Vegetative Propagation

     The offsprings are genetically identical and therefore advantageous traits can be preserved.The plants gradually lose their vigour as there is no genetic variation. They are more prone to diseases that are specific to the species. This can result in the destruction of an entire crop.

Sexual Reproduction

     Sexual reproduction mostly occurs in higher multicellular plants and animals. However, it is also seen in lower organisms like the bacteria, Spirogyra (an alga) and Paramoecium (a protozoan).

Human Reproductive System

     The human beings are bisexual with two separate sexes - male and female. The individuals of the two sexes show distinctive features called the secondary sexual characteristics.

Male Reproductive System

     The male reproductive system comprises of a pair of testes that are present in a thin-walled sac called the scrotum.

Female Reproductive System

     The female reproductive system consists of a pair of ovaries, a pair of oviducts, uterus, vagina and vulva.

Menstruation and Menstrual Cycle

     At about the age of 10 to 13 years, the ovaries of females are stimulated by the follicle stimulating hormone (FSH) of the pituitary. This is called the onset of puberty and is accompanied by release of hormones oestrogen and progesterone.

Fertilisation

     Fertilisation can be defined as the fusion of the sperm nucleus with the egg nucleus to form a diploid cell known as zygote.

Sexual Transmitted Diseases

     The common diseases are syphilis and gonorrhoea. Syphilis is characterized by sores around the anus, vagina, penis, lips, fingers, nipples, etc.

Population Control

     Increasing population is a serious issue, particularly in developing countries. It is necessary for every generation to produce more off springs because many individuals do not survive to reach the reproductive age due to natural causes.

Summary

     Reproduction is defined as the production of individuals of the same species, that is the next generation of the species.

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