Final answer:
The zygote divides and multiplies through mitosis during the first few days of prenatal development, eventually forming a blastocyst.
Step-by-step explanation:
The zygote's function during the first few days of prenatal development is to divide and multiply through a process called mitosis. The zygote starts as a one-cell structure created when a sperm fertilizes an egg. It goes through several divisions, resulting in a mass of cells called a morula, and eventually forms a blastocyst.