NEET BIOLOGY

Detailed explanation-1: -The number of chromosomes isn’t reduced during mitotic cell division because, prior to division, each of the chromosomes replicates (duplicates), meaning that the cell makes an exact copy of each chromosome. This replication process happens during the synthesis (S) phase of the cell cycle.

Detailed explanation-2: -The term “duplication” simply means that a part of a chromosome is duplicated, or present in 2 copies. This results in having extra genetic material, even though the total number of chromosomes is usually normal.

Detailed explanation-3: -It is important that the chromosomes are doubled before mitosis because each of the two resulting daughter cells must have the same amount of DNA as the parent cell. In the process of mitosis, one parent cell divides to make two genetically identical daughter cells that are also identical to the parent cell.

Detailed explanation-4: -The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half-from 46 to 23-to form sperm and egg cells.

Detailed explanation-5: -When one cell divides into two, both must have a copy of the genetic information. Therefore, before cell division occurs, the genes must also make duplicates of themselves so that all of the important genetic information ends up in each of the new cells.