reproduction (image)

It is the external female genital organ. It includes the vaginal orifice, labia majora, labia minora, clitoris and Bartholin glands. The opening of the vagina is closed by 2 muscular folds of skin, the labia majora. Inside these are a pair of labia minora. A sensitive erectile organ about the size ..

Each diploid primary spermatocyte undergoes meiosis I, which is a reduction division. Two daughter cells are formed each with 'n' number of chromosomes. The daughter cells are called secondary spermaotcytes. The secondary spermatocytes are haploid and much smaller comparitively, containing (22+X) o..

In some fungi like Puccinia, tiny unicellular spore like structures called spermatia are formed. They get transferred to female gametangia through various agencies. fig. 8.21 - Types of Sexual Reproduction in Fu..

It is a common type of cell division that occurs in all the cells of an organism. Hence, it is commonly called as somatic cell division. In mitosis, the resulting daughter cells will have the same number of chromosomes and contain the same amount of DNA, as that of the parent cell. Hence, mitosis i..

The nucleus of the megaspore undergoes three successive mitotic divisions forming eight nuclei. The megaspore enlarges into an oval shaped structure called the embryo sac . The eight nuclei of the embryo sac arrange themselves in 3 groups. (A I), (A - D), stages in the development of an ovule and f..

Growth of the Pollen Tube - The pollen grains which reach the sticky stigma, absorb these secretions, swells up and ruptures at one of the germ pores. The thin intine emerges out in the form of a pollen tube which continues to grow and penetrates deep into the styl..

Spermatogenesis - The process of spermatogenesis occurs in the seminiferous tubules of the testes. The whole developmental process of proliferation of spermatogonia or the sperm mother cells to mature spermatozoa or sperm is called as spermatogenesis. The functional spermatozoa or sperms have haplo..

Aerial weak stems like runners and stolons, when they touch the ground, give off adventitious roots. When the connection with the parent plant is broken, the portion with the newly struck roots develops into an independent plant. Some examples for propagation by stem are from stolons - Vallisneria,..

Fertilisation can be defined as the fusion of the sperm nucleus with the egg nucleus to form a diploid cell known as zygote. The fertilisation is internal in the human reproductive system. It is achieved by the insertion of the male organ, penis into the vagina of the female. The sperms a..

Transfer of pollen grains to the stigma is called pollination. If the pollen grains are transferred to the stigma of the same flower, the pollination is called self-pollination or autogamy . If the pollen grains are transferred to the stigma of another flower of the same species, the pollination ..