11. c. crossing-over. Notice how one of the bottom arms of each of the gray and white chromosome overlaps with each other, then their genes switch to the other's arm. That's called crossing over, when homologous chromosomes' genes flip-flop with each other.
14. b. meiosis. Gametes are special daughter cells that are either sperm or egg for sexual reproduction. Since genes are shuffled and daughter cells are not like parent cells, this is meiosis. 1 parent --> 4 non-identical gametes.
16. a. centromeres. During late prophase and all of metaphase of mitosis, identical sister chromatids are fused together at the center of the chromosome "X" by what's called a centromere. Then, during anaphase, the sisters are pulled apart, at these centromeres, by spindles attached to centrioles toward opposite sides of the cell.
17. c. Metaphase only. Although late prophase has this appearance of chromosomes, the best answer is probably only metaphase. It's not in anaphase because that's when sister chromatids are pulled apart at their centromeres.
