AP BIOLOGY

Detailed explanation-1: -zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells.

Detailed explanation-2: -Once fertilized, the egg is called a zygote. Fertilization is not complete, however, until the two haploid nuclei (called pronuclei) have come together and combined their chromosomes into a single diploid nucleus.

Detailed explanation-3: -When a fertilized egg has implanted in the uterus, the group of cells that will become a baby is called an embryo. A developing, fertilized egg is known by several names within the first 2 weeks after conception, including zygote, morula (day 4), and blastocyst (day 5).

Detailed explanation-4: -The fertilized egg (zygote) divides repeatedly as it moves down the fallopian tube to the uterus. First, the zygote becomes a solid ball of cells. Then it becomes a hollow ball of cells called a blastocyst.