3. Why is it sufficient for only the head of the sperm cell to enter the egg cell?
--> Facts:
Fertilisation is the fusion of the nuclei of sperm and egg cell
Fertilisation is the fusion of hereditary information from both parents
The head of the sperm cell contains the nucleus
Explanation:
In order to combine the hereditary information of both parents the fusion of the nuclei of the egg and sperm cell is necessary. As the nucleus of the sperm cell is in the head, no other parts of the sperm cell need to enter the egg cell
--> Conclusion:
It is sufficient for only the head of the sperm cell to enter the egg cell