(a) Which of the following animals undergo external fertilisation?

(i) Amphibians

(ii) Reptiles

(iii) Birds

(iv) Fish

(b) Mention one disadvantage of external fertilisation?

(a) Amphibians and fish are the animals that undergo external fertilisation.

Explanation: The fertilisation occurs outside the body in the water medium. These organisms produce large number of gametes to increase their chances of fertilisation.

(b) The chances of survival of the offsprings are low due to the attack by predators.