Sunday, August 30, 2020

Sexual Reproduction

Sexual reproduction is the process of formation of offspring by fusion of male and female gametes. In higher plants and animals sexual reproduction occurs.

Sexual reproduction in plants: The reproductive organ of plant is flower. Flower has four major parts called calyx or sepal, corolla or petal, androecium(male reproductive part also called stamen) and gynoecium(female reproductive part also called carpel). The function of sepal is to protect flower on bud state and the function of corolla is to attract insects for pollination. These two are vegetative parts of flower and other two(androecium & gynoecium) are reproductive parts. When flower is matured pollen grains are formed inside stamen which by pollination reach to stigma and the process is called pollination. Air, honey bee and other insects play role on pollination of flower. After pollination process pollen grains slowly reach to ovary via pollen tube and diffuse to ovules inside ovary. The process of fusion of pollen grains with ovules is called fertilization. After fertilization process zygote is formed which later on develops to embryo. Embryo is enclosed and protected by seed. When seed gets proper environment it emerges as new plant.

Sexual reproduction in animals: In animals male produce sperms as reproductive cell and female produce ovum. When sperm is fused with ovum zygote is formed and the process of fusion of gametes is called fertilization. In animals there are two types of fertilizations

  1. External fertilization in which male fertilize eggs of female out of female’s body. Fish, frog and salamander fertilize externally.
  2. Internal fertilization in which ovum is fertilized by male inside female’s body by sexual intercourse. Reptiles, mammals and birds fertilize internally.

After fertilization and zygote formation embryo is formed and developing the embryo new animal baby is formed.


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