AP BIOLOGY

Detailed explanation-1: -The first and longest phase of mitosis is prophase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope, or membrane, breaks down . In animal cells, thecentrioles near the nucleus begin to separate and move to opposite poles (sides) of the cell.

Detailed explanation-2: -Prophase is the first step of mitosis, during which chromosomes condense and the nuclear envelope dissolves. Metaphase follows prophase. During metaphase, the chromosomes align in the center of the cell at the equatorial plate and the spindle fibers attach to the centromeres of the chromosomes.

Detailed explanation-3: -Answer and Explanation: The spindle formation begins during the prophase. During the prophase, the movement of centromeres towards the two ends results in the formation of tube-like structures called the spindle fibers. These get assembled between the centromeres and the poles.

Detailed explanation-4: -Micrographs illustrating the progressive stages of mitosis in a plant cell. During prophase, the chromosomes condense, the nucleolus disappears, and the nuclear envelope breaks down.

Detailed explanation-5: -The nuclear membrane fragments during prometaphase and the mitotic spindle, consisting of microtubules and associated proteins, forms between the two centrioles.