Fertilisation Flashcards
Fertilisation
Fertilisation is the moment when the active sperm penetrates the mature egg.
Fertilization is the process by which a sperm cell and an egg cell unite to form a completely new individual.
Internal Fertilisation
Animals that have internal fertilization have completely transitioned to life on land. Fewer young are produced because the mother’s body will protect any fertilized eggs from being devoured by predators, so large numbers of eggs aren’t needed.
External Fertilisation
External fertilization requires the presence of water for the sperm to be able to unite with the egg. Both eggs and sperm are released into the water, and the sperm must swim to reach the eggs. Organisms that use external fertilization to reproduce must either live in the water or return to the water for reproduction.
Advantages of Internal Fertilisation
Increase chance gametes meet
greater chance of successful fertilisation
More protection against outside environments and predators, and therefore a higher chance of surviving until birth.
Disadvantages of Internal Fertilisation
Harder to bring both male and female into intimate contact
Limited amount of offspring being produced at any given time.
Higher risk of sexually transmitted diseases being passed on.
Advantages of External Fertilisation
Results in the production of a large number of offspring
Easier to find mates as the gametes released can drift (wind, water etc).
More genetic variation
Disadvantages of External Fertilisation
Environmental hazards such as predators reduce the change of surviving into adulthood.
Large amounts of gametes go unfertilised and wasted.
Not guaranteed that sperm will come in contact with eggs
Greater chance of desiccation of gametes/zygotes.
E.g. Internal
Humans, chickens, birds, alligators
E.g.External
Frogs, many types of fish, marine invertebrates
