Internal vs External fertilisation – HSC Biology


Internal and external fertilization will both lead to the continuation of the species, both of these are sexual reproduction methods. The continuation of a species occurs via sexual or asexual reproduction.

A good example of external fertilisation is the salmon, the female salmons will lay their eggs on the banks and then the male salmon will come and fertilize those eggs. External fertilisation typically occurs in an aqueous environment. A large number of offspring are produced. Due to that large number of offspring and the fact that the eggs mature outside of the mother, there’s is going to be a low amount of paternal care. Therefore, it’s actually going to have a lower energy cost.

Whereas, with internal fertilization which is an example occurring in humans, this is typically going to occur in a dry environment. Typically fewer offspring are produced. However, the offspring will be maturing inside the mother so there is actually going to be a higher amount of paternal care and that means we’ll have a higher energy cost.

Both of these processes result in an increase in the genetic diversity hence allowing for the continuation of the species.



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Question 1.

Explain how internal and external fertilisation both lead to the continuation of a species [6 marks]

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