Fertilization is the biological process in which male and female gametes (sperm and egg cells) unite to form a zygote, which subsequently develops into an embryo. This process is crucial for sexual reproduction in many organisms, including animals and plants.
In animals, fertilization usually occurs within the female's reproductive system, though it can be external (as in many fish and amphibians) or internal (as in mammals). The zygote contains genetic material from both parents and begins to divide and differentiate, eventually leading to the development of a new individual.
In plants, fertilization typically involves the fusion of male gametes from pollen with female gametes in the ovule, leading to the formation of seeds. This process is often aided by pollinators or other mechanisms that facilitate the transfer of pollen.
Overall, fertilization is a critical step in the reproductive cycle that ensures genetic diversity and the continuation of species.