Question

Internal fertilization occurs in higher animals due to
a. Copulatory organs
b. Ensure fertilization
c. Protection of semen
d. Terrestrial residence

Answer 1

Fertilization or syngamy is the complete and permanent fusion of male and female gametes to form the zygote. It occurs in the case of sexual reproduction only as there is no gamete formation in the asexual mode of reproduction.

Complete answer:
The fertilization in animals is of two types depending upon the method of birth of offspring- external fertilization and internal fertilization.
- External fertilization involves the fusion of gametes outside the body, e.g. spawning in frogs.
- Internal fertilization involves the fusion of male gamete and female gamete inside the body of the parent. This requires males to implant their sperm in the female reproductive tracts.

Different animals have different techniques for this. Copulation is the most common method which involves the transfer of sperm by insertion of male copulatory organ like penis into the female reproductive organ like vagina.

In some organisms like birds, sperm transfer occurs through cloacal kiss which involves birds pressing their cloaca together. Some other animals transfer spermatophore which is a bindle containing sperm in the female body and it is stored till oviposition in the female takes place, e.g. salamander, arachnids, mollusks, etc.

So for internal fertilization to occur, it is necessary that animals have well developed copulatory organs. For example, in humans, males have penis and females have a vagina as their copulatory organs. The penis is an erectile organ which is meant for the deposition of semen into the vagina of the female which is a tubular and long muscular canal like structure with a mucous membrane.

Hence, the correct answer is option (A).

Note: External fertilization has some pros like it reduces the chances of transmission of sexually transmitted diseases and increases the genetic variation in the population. Animals that are viviparous, oviparous and ovoviviparous in nature, generally show internal fertilization.