Question

Beginning with a fertilized egg (zygote) how many cells would be present in an embryo .

A) 2 cells (after the first cell division)
B) 16 cells (morula stage)
C) Hundreds of cells (blastocyst stage)
D) Thousands of cells (gastrula stage)

Answer 1

The correct answer is D) Thousands of cells (gastrula stage). The zygote divides by mitosis to form two daughter cells, and by day 4, it forms a solid ball of approximately sixteen cells called a morula. The blastocyst stage is characterized by hundreds of cells, and during the gastrula stage, there are thousands of cells present.

Step-by-step explanation:

The correct answer is D) Thousands of cells (gastrula stage). After fertilization, the single-celled zygote undergoes mitosis to form two daughter cells. Mitosis continues, and by day 4, there are approximately sixteen cells, forming a solid ball called a morula. As more cell divisions occur, the embryo develops into a blastocyst stage, with hundreds of cells. Finally, during the gastrula stage, there are thousands of cells present as the cells continue to divide and differentiate.