Canadian Practical Nurse Registration Examination (CPNRE) Practice Exam

The formation of twins from the splitting of one zygote leads to the development of monozygotic twins, also known as identical twins. This process occurs when a single fertilized egg (the zygote) divides into two separate embryos during the early stages of development. Since these twins originate from the same genetic material, they share identical DNA, which results in them having the same sex and very similar physical characteristics.

In contrast, dizygotic twins, or fraternal twins, occur when two separate eggs are fertilized by two different sperm cells, leading to genetically unique siblings. Identical twins is another term that describes the same group as monozygotic twins, but "monozygotic" more accurately describes the biological process of their formation. Fraternal twins are not formed from a single zygote; rather, they are distinct entities from the beginning. Thus, the correct identification of twins formed by the splitting of a single zygote is monozygotic twins.