Question

Example of external fertilization is
A. Fish and frog
B. Frog and monkey
C. Dog and goat
D. Goat and fish

Answer 1

Hint: External fertilization is commonly observed in aquatic animals. Generally, animals undergoing external fertilization lays many eggs to ensure a high success rate of fertilization.

Complete answer:
Fertilization is a process in which sperm fuses with an egg to form a zygote. Fertilization is of two types: internal fertilization and external fertilization. External fertilization takes place in the exterior of a female body. When a male as well female animal approaches each other, the female lays many eggs. These eggs are generally delicate and a jelly coating collectively holds these eggs and gives protection to the eggs. Now, the male will lay down sperms, each of which will swim in the water and reach the egg. When both egg and sperm fuse together, fertilization occurs. This form of external fertilization is commonly observed in aquatic animals like fish.
Frogs also undergo external reproduction. The eggs and sperms of a frog are released into the water. The larval stage of a frog is in water and the adult phase of the frog is on land.

External fertilization advantages
-Genetic variation is enhanced because of the broadcast spawning.
-At a time, a large number of eggs as well as sperms are released and thus enhances the probability of occurrence of a large number of fertilisations leading to the overall increase in the offspring production.
-Eggs can effortlessly find their mates.
-It is a simple process as it does not require hormones for reproduction.

External fertilization disadvantages
-A huge amount of gametes is needed to enhance the success rate of reproduction.
-The fertilization rate is also decreased by the attack of eggs by the predators and the impact of various environmental factors.
-The sperm as well as eggs may not come in contact with each other.
-Since the eggs, sperm, and zygote formed are delicate, they might become dry and might break.
-An aqueous environment is required for the fertilization to occur else the sperm will die in the terrestrial environment.

So, the correct answer is ‘Fish and frog’.

Note: In animals that reproduce via external fertilization, the embryo development takes place within the egg outside the female body. After the complete growth of an embryo, the eggs will hatch. Furthermore, external fertilization can also be artificially performed in humans in those situations where the egg and sperm cannot fuse together for the fertilization process. This type of external fertilization in humans is called in-vitro fertilization.