What is the process called that involves halving the chromosome number?

The process that involves halving the chromosome number is known as Meiosis I. During Meiosis I, homologous chromosomes are separated and distributed into two new cells, reducing the chromosome number by half. This is a critical step in sexual reproduction, as it ensures that when gametes fuse during fertilization, the resulting zygote has the correct diploid chromosome number.

Meiosis I includes stages such as prophase I, metaphase I, anaphase I, and telophase I, during which homologous chromosomes undergo recombination and are aligned before being pulled apart. This reduction division is essential for maintaining chromosome stability across generations.

Mitosis, on the other hand, is a process that results in the division of somatic cells, maintaining the same chromosome number in the daughter cells as in the parent cell. Fertilization is the union of two gametes, which restores the diploid chromosome number but does not itself involve the halving of chromosome number. Meiosis II subsequently separates sister chromatids but does not reduce the chromosome number further.