At the beginning of human development, how many cells does a human start as?

• A. One cell
• B. Two cells
• C. Eight cells
• D. Four cells

Answer: (A)

Verified step by step guidance

1. Understand that human development begins with a single fertilized egg cell, known as a zygote.
2. Recognize that the zygote is formed when a sperm cell fertilizes an egg cell, resulting in one cell with a complete set of chromosomes.
3. Acknowledge that this single cell, the zygote, undergoes a series of divisions called mitosis to form more cells.
4. Note that the initial stage of human development starts with this one cell, which will eventually divide to form two cells, then four, and so on.
5. Conclude that at the very beginning of human development, the process starts with one cell, the zygote.