NEET BIOLOGY

Detailed explanation-1: -A normal human cell has 23 pairs chromosomes. So, a total of 46 chromosomes. At the bivalent stage, each chromosome has two chromatids. So a total of 92 chromatids.

Detailed explanation-2: -Prophase: During prophase, the nuclear envelope of the cell (which is where the 92 sister chromatids are contained) begins to break down. The centrioles, which are only present in animal cells, separate and each moves to an opposite end of the cell.

Detailed explanation-3: -During metaphase, there are 46 chromosomes composed of two sister chromatids each that align at the metaphase plate. Then, during anaphase, these chromatids are separated and pulled to opposite poles of the cell. This separation results in 92 separate chromatids in the cell, which are considered 92 chromosomes.

Detailed explanation-4: -Mitosis causes the number of chromosomes to double to 92, and then split in half back to 46. This process repeats constantly in the cells as the baby grows. Mitosis continues throughout your lifetime. It replaces skin cells, blood cells, and other types of cells that are damaged or naturally die.

Detailed explanation-5: -At the beginning of meiosis I, a human cell contains 46 chromosomes, or 92 chromatids (the same number as during mitosis).