sexual reproduction

sexual reproduction is the process of fertilization, whereby the male and female sex cells fuse, or bond. Fertilization may be of two types, either internal or external. Animals typically produce male gametes called sperm, and female gametes called eggs and ova, following immediately after meiosis.

Sexual reproduction is a complex process involving two individuals or parents of different sexes i.e. male and female. The formation of two different types of gametes by male and female takes place in their gonads i.e., testis in male and ovary in female. The sperms are produced in the testis and ova are produced by ovary. Therefore testes and ovaries are called primary sex organs. The spermatozoa are formed in the testis by the process of spermatogenesis and ova in the ovary by the process of oogenesis. The spermatogenesis and oogenesis are altogether known as gametogenesis. The formation of gametes by gonads is the primary sex character of male and female. In association with this, secondary sex characters also develop in sexually reproducing animals.

Flowering plants

The anther produces male gametophytes, the sperm is produced in pollen grains, which attach to the stigma on top of a carpel, in which the female gametophytes (inside ovules) are located. After the pollen tube grows through the carpel's style, the sex cell nuclei from the pollen grain migrate into the ovule to fertilize the egg cell and endosperm nuclei within the female gametophyte in a process termed double fertilization. The resulting zygote develops into an embryo, while the triploid endosperm (one sperm cell plus two female cells) and female tissues of the ovule give rise to the surrounding tissues in the developing seed. The ovary, which produced the female gametophyte(s), then grows into a fruit, which surrounds the seed(s). Plants may either self-pollinate or cross-pollinate. Nonflowering plants like ferns, moss and liverworts use other means of sexual reproduction.