external fertilisation
Answers
Answer:
External fertilisation
When fusion of male and female gametes takes place outside the body of the female, it is called external fertilisation. It is very common in aquatic animals like fish and frog. In such animals fertilisation takes place in water.
The female lays hundreds of eggs in slow-moving streams. The eggs do not have hard covers, but a delicate layer of jelly that holds the eggs together. The male of these species deposit sperms on this cluster of eggs. As the eggs and sperms come in contact, the eggs are fertilised.
During external fertilisation only a few fertilised eggs are able to form full grown organisms .The animals that reproduce through external fertilisation lay hundreds of eggs and release millions of sperms into the water, but not all the eggs get fertilised for various reasons. The eggs and sperms released into the water are exposed to the wind, rainfall and movement of water, which may scatter them before fertilisation can occur. Also, these eggs are eaten by other aquatic animals.
Answer:
Fusion of sperm of a male and female gamete that leads to the formation of a Zygote.