Answer:
During metaphase 1, the chromosomes line up in the middle of the cell. The way the chromosomes line up is random, or independent. This independent alignment results in different possible arrangements or assortments of chromosomes during metaphase. This in turn results in different sets of chromosomes in daughter cells. During sexual reproduction, the traits that are determined by the genes on these chromosomes are passed on from parents to offspring.
Explanation:
In metaphase, the typical chromosome is formed by two chromatids joined by a centromere. Each chromatid is composed of a sequence of chromatin ringlets domains. During metaphase I, fibers of the spindle apparatus capture chromosomes and take them toward the center of the cell, to the metaphase plate. Each chromosome of the pair joins with a microtubule of only one of the spindle poles, so the two equivalent chromosomes join the fibers of opposites poles.
The homologous pairs of chromosomes get aligned in the metaphase plate for their posterior separation in anaphase I. When they align in the center of the cell, their orientation is random.