Understanding Internal Fertilization in Animals

Fertilization is a crucial step in sexual reproduction where the male gamete (sperm) fuses with the female gamete (egg) to form a zygote. This process can occur either outside the body of the female (external fertilization) or inside the body of the female (internal fertilization).

External vs. Internal Fertilization

Let's briefly understand the difference:

• External Fertilization: In this type, the fusion of sperm and egg takes place outside the body of the female, usually in a watery environment. Both the male and female discharge their gametes into the water, where fertilization occurs.
• Internal Fertilization: In this type, the fusion of sperm and egg takes place inside the body of the female. The male deposits sperm into the female's reproductive tract.

Analyzing the Options

Now let's look at the given animal options to determine which one typically undergoes internal fertilization:

• Fish: Most fish exhibit external fertilization. The female lays eggs in the water, and the male releases sperm over the eggs. There are exceptions, like some sharks and guppies, which have internal fertilization, but external fertilization is the general rule for bony fish.
• Frog: Frogs are amphibians. They reproduce through external fertilization. The female lays eggs (spawn) in water, and the male fertilizes them externally.
• Reptile: Reptiles, such as snakes, lizards, turtles, and crocodiles, reproduce through internal fertilization. The male deposits sperm into the female's cloaca before the eggs are laid. This adaptation allows reptiles to reproduce on land, as they do not need a watery environment for fertilization.
• None of these: Based on the analysis, one of the options does undergo internal fertilization, so this option is incorrect.

Conclusion

Based on the typical modes of reproduction in these animal groups, reptiles are known to undergo internal fertilization.