Certificate In Psychology (CPSY) Practice Exam

What term best describes the stage of development immediately following fertilization?

1. Embryonic stage

2. Fetal stage

3. Gamete stage

4. Zygotic stage

The correct answer is: Zygotic stage

The term that best describes the stage of development immediately following fertilization is the zygotic stage. During this period, the fertilized egg, known as a zygote, undergoes a series of rapid cell divisions called cleavage as it travels down the fallopian tube towards the uterus. This stage is critical because it marks the first stage of human development, where the genetic material from the sperm and egg combines to form a unique organism. The zygotic stage lasts until the formation of a blastocyst, which is necessary for implantation into the uterine wall. In contrast, the embryonic stage occurs after the zygotic stage, once the blastocyst implants and begins to further develop major organ systems. The fetal stage follows the embryonic stage, representing a later phase of development characterized by rapid growth and maturation of already formed structures. The gamete stage refers to the individual reproductive cells—sperm and egg—prior to fertilization, which does not pertain to the stage immediately after fertilization.