Define external fertilisation. Mention its disadvantages.

Explanation

External fertilisation occurs outside the boby of the orgnisms. During this process, the parents release sperms and eggs into surrounding water (example, frog) where fetilisation occurs. The major disadvantages of this type of fertilisation are : (i) the fertilisation of egg is not always are sure, (ii) the offspring are not protected from the predatores, and (iii) a large number of gametes are wasted.