Choose the incorrect statement from the following:

1. In birds and mammals, internal fertilisation takes place.
2. Colostrum contains antibodies and nutrients.
3. Polyspermy is prevented by the chemical changes in the egg surface.
4. In the human female, implantation occurs almost seven days after fertilisation.


(C) Polyspermy describes on egg that has been fertilised by more than one sperm. During fertilisation, binding of the sperm to the egg induces depolarisation of the egg plasma membrane that block the entry of additional sperms. Rest all statements are correct.