Railway Science (Biology-Reproduction in Animals) (Part-II)

Hydra - Belong to Phylum Coelenterata. Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. Examples are Bacteria, Yeast, Corals, Flatworms, Jellyfish and Sea anemones.
Other types of modes of reproduction used by single organisms: Fission, Fragmentation, Regeneration, vegetative propagation, spore formation.

The ovary produces female gametes called ‘ova’ and the testes produce male gametes called ‘sperms’. The fusion of ovum and sperm is called fertilization. The fertilized egg is called a zygote.

Uterus is a reproductive organ in females where the fertilized egg implants and develops into a fetus during pregnancy. The sperms enter through the vaginal passage during sexual intercourse.
They travel upwards and reach the oviduct where they may encounter the egg. The fertilised egg, the zygote, gets implanted in the lining of the uterus, and starts dividing.

Sexual reproduction allows for a greater genetic diversity through the process of Fertilisation. It involves the meiosis process which means a cell doubling its DNA, shuffling its genes and then dividing the shuffled DNA among four cells.

In humans, non-motile and food storing germ cell is ovum and the motile germ cell is sperm. This is true for all the organisms who reproduce sexually.

The Male reproductive organs include Testes, Scrotum, sex accessory ducts (rete testis, vasa efferentia, epididymis and vas deferens) and Penis. The female reproductive organs are a pair of Ovaries, Oviducts (Fallopian tubes), Cervix, Vagina and Uterus.

Binary fission - A form of asexual reproduction in which an organism divides into two and each part is genetically identical to the parent cell. Example: Paramecium and Leishmania.
Budding - A small bud forms on the body of the parent organism and eventually separates to form a new individual. Example: Hydra and Yeast.

Two main categories of reproduction: In sexual reproduction, an organism combines the genetic information from each of its parents and is genetically unique. In asexual reproduction, one parent copies itself to form a genetically identical offspring.

The fusion of male gamete and female gamete is called fertilization. A zygote is a diploid cell that is formed by the fusion of male and female haploid gamete cells.

The umbilical cord is the vital connection between the fetus and the placenta. The umbilical cord is composed of two umbilical arteries and one umbilical vein surrounded by a gelatin-like extracellular matrix known as Wharton’s jelly. The cervix is a fibromuscular organ that links the uterine cavity to the vagina.