Why is there two variations of each characteristic?

Please explain :) !!

Will mark brainliest i only need the ! 1.use ten beads and a centromere of one color to construct the long chromosome. use ten beads and a centromere of a second color to construct the second chromosome in the long pair. make a drawing of the chromosomes in the space below. 2. for the second pair of chromosomes, use only five beads. 3. now model the replication of the chromosomes. make a drawing of your model in the space below. part b: meiosis i during meiosis i, the cell divides into two diploid daughter cells. 4. pair up the chromosomes to form tetrads. use the longer tetrad to model crossing-over. make a drawing of the tetrads in the space below. 5. line up the tetrads across the center of your “cell.” then model what happens to the chromosomes during anaphase i. 6. divide the cell into two daughter cells. use the space below to make a drawing of the result. part c: meiosis ii during meiosis ii, the daughter cells divide again. 7. line up the chromosomes at the center of the first cell, one above the other. separate the chromatids in each chromosome and move them to opposite sides of the cell. 8. repeat step 7 for the second cell. 9. divide each cell into two daughter cells. use the space below to make a drawing of the four haploid cells