AP BIOLOGY

Detailed explanation-1: -Chromosomes become visible during prophase. Chromatin is in its least condensed stage during the interphase stage. It begins its condensation during the prophase stage and is visible until the end of cell division.

Detailed explanation-2: -In prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphase plate.

Detailed explanation-3: -Throughout the process of prophase the chromosomes condense meaning they get shorten and thicken to form visibly distinct threads within the nucleus. This is brought about by the action of large proteins called condensins.

Detailed explanation-4: -During prophase I, the chromosomes condense and become visible inside the nucleus. Because each chromosome was duplicated during the S phase that occurred just before prophase I, each now consists of two sister chromatids joined at the centromere.