Give examples and explain what is meant by external fertilization? (AS1)

a) External fertilization can be defined as the fertilization that takes place outside the female’s body.

b) External fertilization is mostly common in aquatic organisms such as fishes and amphibians.

c) During the time of mating, the female lays a large number of eggs in the water and male releases millions of sperms on them in water. The zygote thus formed after the fusion of gametes is protected in a jelly-like structure where it grows and develops.

d) Since the chances of fertilization or the development and survival of the zygote are totally dependent on nature, a large number of eggs and sperms are produced and released every cycle.

e) For example: Fishes, frogs and other amphibians.