Certificate In Psychology (CPSY) Practice Exam

What is the composition of a zygote?

1. a ball of about 100 identical cells.

2. three layers of cells.

3. an interdependent group of cells.

4. a single cell.

The correct answer is: a single cell.

The composition of a zygote is that it is a single cell. This single cell is formed when a sperm cell fertilizes an egg cell, resulting in a zygote that contains a complete set of genetic material from both parents. The zygote undergoes a series of divisions called cleavage, where it transforms from a single cell into multiple cells that will form the embryo. In early development, the zygote is not yet a ball of identical cells nor does it consist of layers or interdependent cells in its initial state. It starts as one unified cell, which then begins a complex journey of development where it will eventually form multiple layers and specialized cells as it progresses through different stages of embryonic development.